Adv Sci (Weinh) , IF:15.84 , 2020 Feb , V7 (3) : P1901455 doi: 10.1002/advs.201901455
Root Growth Adaptation is Mediated by PYLs ABA Receptor-PP2A Protein Phosphatase Complex.
State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological Sciences China Agricultural University Beijing 100193 China.; Institute of Science and Technology Austria Am Campus 1 3400 Klosterneuburg Austria.; State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River Nanjing Agricultural University Nanjing 210095 China.
Plant root architecture dynamically adapts to various environmental conditions, such as salt-containing soil. The phytohormone abscisic acid (ABA) is involved among others also in these developmental adaptations, but the underlying molecular mechanism remains elusive. Here, a novel branch of the ABA signaling pathway in Arabidopsis involving PYR/PYL/RCAR (abbreviated as PYLs) receptor-protein phosphatase 2A (PP2A) complex that acts in parallel to the canonical PYLs-protein phosphatase 2C (PP2C) mechanism is identified. The PYLs-PP2A signaling modulates root gravitropism and lateral root formation through regulating phytohormone auxin transport. In optimal conditions, PYLs ABA receptor interacts with the catalytic subunits of PP2A, increasing their phosphatase activity and thus counteracting PINOID (PID) kinase-mediated phosphorylation of PIN-FORMED (PIN) auxin transporters. By contrast, in salt and osmotic stress conditions, ABA binds to PYLs, inhibiting the PP2A activity, which leads to increased PIN phosphorylation and consequently modulated directional auxin transport leading to adapted root architecture. This work reveals an adaptive mechanism that may flexibly adjust plant root growth to withstand saline and osmotic stresses. It occurs via the cross-talk between the stress hormone ABA and the versatile developmental regulator auxin.
PMID: 32042554
Trends Plant Sci , IF:14.416 , 2020 Feb , V25 (2) : P126-129 doi: 10.1016/j.tplants.2019.11.006
MAPK Signaling: Emerging Roles in Lateral Root Formation.
Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China.; Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China. Electronic address: xzmeng@shnu.edu.cn.
Lateral root (LR) formation is a multistep developmental process in which auxin and peptide hormones play essential roles. Recent studies in arabidopsis by Huang et al. and Zhu et al. have revealed that the mitogen-activated protein kinase (MAPK) cascade MKK4/MKK5-MPK3/MPK6 functions in both a noncanonical auxin signaling pathway and the IDA peptide signaling pathway to regulate LR morphogenesis and emergence, respectively.
PMID: 31848035
Trends Plant Sci , IF:14.416 , 2020 Feb , V25 (2) : P121-123 doi: 10.1016/j.tplants.2019.12.001
Adaptive Growth: Shaping Auxin-Mediated Root System Architecture.
Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China; Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou 450001, China. Electronic address: guanghuix@snnu.edu.cn.; Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria. Electronic address: yuzhou.zhang@ist.ac.at.
Root system architecture (RSA), governed by the phytohormone auxin, endows plants with an adaptive advantage in particular environments. Using geographically representative arabidopsis (Arabidopsis thaliana) accessions as a resource for GWA mapping, Waidmann et al. and Ogura et al. recently identified two novel components involved in modulating auxin-mediated RSA and conferring plant fitness in particular habitats.
PMID: 31843370
Nat Commun , IF:12.121 , 2020 Feb , V11 (1) : P1053 doi: 10.1038/s41467-020-14905-w
The epidermis coordinates thermoresponsive growth through the phyB-PIF4-auxin pathway.
Department of Life Sciences, Korea University, Seoul, Korea.; Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, 61186, Korea.; Department of Biological Sciences, KAIST, Daejeon, Korea.; Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.; Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan.; Department of Life Sciences, Korea University, Seoul, Korea. ekoh@korea.ac.kr.
In plants, an elevation in ambient temperature induces adaptive morphological changes including elongated hypocotyls, which is predominantly regulated by a bHLH transcription factor, PIF4. Although PIF4 is expressed in all aerial tissues including the epidermis, mesophyll, and vascular bundle, its tissue-specific functions in thermomorphogenesis are not known. Here, we show that epidermis-specific expression of PIF4 induces constitutive long hypocotyls, while vasculature-specific expression of PIF4 has no effect on hypocotyl growth. RNA-Seq and qRT-PCR analyses reveal that auxin-responsive genes and growth-related genes are highly activated by epidermal, but not by vascular, PIF4. Additionally, inactivation of epidermal PIF4 or auxin signaling, and overexpression of epidermal phyB suppresses thermoresponsive growth, indicating that epidermal PIF4-auxin pathways are essential for the temperature responses. Further, we show that high temperatures increase both epidermal PIF4 transcription and the epidermal PIF4 DNA-binding ability. Taken together, our study demonstrates that the epidermis regulates thermoresponsive growth through the phyB-PIF4-auxin pathway.
PMID: 32103019
Nat Commun , IF:12.121 , 2020 Feb , V11 (1) : P1069 doi: 10.1038/s41467-020-14891-z
The genome evolution and low-phosphorus adaptation in white lupin.
Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Jinshan, Fuzhou, 350002, China. wfxu@fafu.edu.cn.; Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Jinshan, Fuzhou, 350002, China. qian_z@fafu.edu.cn.; Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Jinshan, Fuzhou, 350002, China.; Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops of the Ministry of Agriculture, Sino-Dutch Joint Laboratory of Horticultural Genomics, Beijing, China.; Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Jinshan, Fuzhou, 350002, China. tyxiagenetics@126.com.; Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops of the Ministry of Agriculture, Sino-Dutch Joint Laboratory of Horticultural Genomics, Beijing, China. chengfeng@caas.cn.
White lupin (Lupinus albus) is a legume crop that develops cluster roots and has high phosphorus (P)-use efficiency (PUE) in low-P soils. Here, we assemble the genome of white lupin and find that it has evolved from a whole-genome triplication (WGT) event. We then decipher its diploid ancestral genome and reconstruct the three sub-genomes. Based on the results, we further reveal the sub-genome dominance and the genic expression of the different sub-genomes varying in relation to their transposable element (TE) density. The PUE genes in white lupin have been expanded through WGT as well as tandem and dispersed duplications. Furthermore, we characterize four main pathways for high PUE, which include carbon fixation, cluster root formation, soil-P remobilization, and cellular-P reuse. Among these, auxin modulation may be important for cluster root formation through involvement of potential genes LaABCG36s and LaABCG37s. These findings provide insights into the genome evolution and low-P adaptation of white lupin.
PMID: 32103018
Nat Commun , IF:12.121 , 2020 Feb , V11 (1) : P679 doi: 10.1038/s41467-020-14395-w
A phosphorylation-based switch controls TAA1-mediated auxin biosynthesis in plants.
Shanghai Center for Plant Stress Biology, Centre for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 201602, People's Republic of China.; FAFU-Joint Centre, Horticulture and Metabolic Biology Centre, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, People's Republic of China.; University of Chinese Academy Sciences, Beijing, 100049, People's Republic of China.; Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA.; FAFU-Joint Centre, Horticulture and Metabolic Biology Centre, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, People's Republic of China. tdxu@sibs.ac.cn.
Auxin determines the developmental fate of plant tissues, and local auxin concentration is precisely controlled. The role of auxin transport in modulating local auxin concentration has been widely studied but the regulation of local auxin biosynthesis is less well understood. Here, we show that TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA1), a key enzyme in the auxin biosynthesis pathway in Arabidopsis thaliana is phosphorylated at Threonine 101 (T101). T101 phosphorylation status can act as an on/off switch to control TAA1-dependent auxin biosynthesis and is required for proper regulation of root meristem size and root hair development. This phosphosite is evolutionarily conserved suggesting post-translational regulation of auxin biosynthesis may be a general phenomenon. In addition, we show that auxin itself, in part via TRANS-MEMBRANE KINASE 4 (TMK4), can induce T101 phosphorylation of TAA1 suggesting a self-regulatory loop whereby local auxin signalling can suppress biosynthesis. We conclude that phosphorylation-dependent control of TAA1 enzymatic activity may contribute to regulation of auxin concentration in response to endogenous and/or external cues.
PMID: 32015349
Plant Cell , IF:9.618 , 2020 Feb , V32 (2) : P352-373 doi: 10.1105/tpc.19.00647
Reprogramming of Root Cells during Nitrogen-Fixing Symbiosis Involves Dynamic Polysome Association of Coding and Noncoding RNAs.
Instituto de Biotecnologia y Biologia Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Cientifico y Tecnologico-La Plata, Consejo Nacional de Investigaciones Cientificas y Tecnicas, 1900-La Plata, Argentina.; Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521.; J. Craig Venter Institute, Rockville, Maryland 20850.; Instituto de Biotecnologia y Biologia Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Cientifico y Tecnologico-La Plata, Consejo Nacional de Investigaciones Cientificas y Tecnicas, 1900-La Plata, Argentina ezanetti@biol.unlp.edu.ar.
Translational control is a widespread mechanism that allows the cell to rapidly modulate gene expression in order to provide flexibility and adaptability to eukaryotic organisms. We applied translating ribosome affinity purification combined with RNA sequencing to characterize translational regulation of mRNAs at early stages of the nitrogen-fixing symbiosis established between Medicago truncatula and Sinorhizobium meliloti Our analysis revealed a poor correlation between transcriptional and translational changes and identified hundreds of regulated protein-coding and long noncoding RNAs (lncRNAs), some of which are regulated in specific cell types. We demonstrated that a short variant of the lncRNA Trans-acting small interference RNA3 (TAS3) increased its association to the translational machinery in response to rhizobia. Functional analysis revealed that this short variant of TAS3 might act as a target mimic that captures microRNA390, contributing to reduce trans acting small interference Auxin Response Factor production and modulating nodule formation and rhizobial infection. The analysis of alternative transcript variants identified a translationally upregulated mRNA encoding subunit 3 of the SUPERKILLER complex (SKI3), which participates in mRNA decay. Knockdown of SKI3 decreased nodule initiation and development, as well as the survival of bacteria within nodules. Our results highlight the importance of translational control and mRNA decay pathways for the successful establishment of the nitrogen-fixing symbiosis.
PMID: 31748328
Curr Biol , IF:9.601 , 2020 Feb , V30 (3) : P381-395.e8 doi: 10.1016/j.cub.2019.11.058
Salicylic Acid Targets Protein Phosphatase 2A to Attenuate Growth in Plants.
Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria.; Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190 Vienna, Austria.; Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria; Department of Experimental Plant Biology, Faculty of Science, Charles University, Vinicna 5, 128 44 Prague 2, Czech Republic.; Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria; Laboratory of Growth Regulators, The Czech Academy of Sciences, Institute of Experimental Botany & Palacky University, Faculty of Science, Slechtitelu 27, 783 71 Olomouc, Czech Republic.; Laboratory of Growth Regulators, The Czech Academy of Sciences, Institute of Experimental Botany & Palacky University, Faculty of Science, Slechtitelu 27, 783 71 Olomouc, Czech Republic.; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium.; Department of Experimental Plant Biology, Faculty of Science, Charles University, Vinicna 5, 128 44 Prague 2, Czech Republic; Institute of Experimental Botany, The Czech Academy of Sciences, Rozvojova 263, 165 02 Prague 6, Czech Republic.; Laboratory of Growth Regulators, The Czech Academy of Sciences, Institute of Experimental Botany & Palacky University, Faculty of Science, Slechtitelu 27, 783 71 Olomouc, Czech Republic; Department of Organic Chemistry, Faculty of Science, Palacky University, tr. 17. listopadu 1192/12, CZ-771 46 Olomouc, Czech Republic.; Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria. Electronic address: jiri.friml@ist.ac.at.
Plants, like other multicellular organisms, survive through a delicate balance between growth and defense against pathogens. Salicylic acid (SA) is a major defense signal in plants, and the perception mechanism as well as downstream signaling activating the immune response are known. Here, we identify a parallel SA signaling that mediates growth attenuation. SA directly binds to A subunits of protein phosphatase 2A (PP2A), inhibiting activity of this complex. Among PP2A targets, the PIN2 auxin transporter is hyperphosphorylated in response to SA, leading to changed activity of this important growth regulator. Accordingly, auxin transport and auxin-mediated root development, including growth, gravitropic response, and lateral root organogenesis, are inhibited. This study reveals how SA, besides activating immunity, concomitantly attenuates growth through crosstalk with the auxin distribution network. Further analysis of this dual role of SA and characterization of additional SA-regulated PP2A targets will provide further insights into mechanisms maintaining a balance between growth and defense.
PMID: 31956021
New Phytol , IF:8.512 , 2020 Feb doi: 10.1111/nph.16375
Regulation of root adaptive anatomical and morphological traits during low soil oxygen.
Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 3rd Floor, 2100, Copenhagen, Denmark.; UWA School of Agriculture and Environment, Faculty of Science, The University of Western Australia, Crawley, WA, 6009, Australia.; Plant Developmental Biology and Physiology, University of Kiel, Am Botanischen Garten 5, 24118, Kiel, Germany.; Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.
Flooding causes oxygen deprivation in soils. Plants adapt to low soil oxygen availability by changes in root morphology, anatomy, and architecture to maintain root system functioning. Essential traits include aerenchyma formation, a barrier to radial oxygen loss, and outgrowth of adventitious roots into the soil or the floodwater. We highlight recent findings of mechanisms of constitutive aerenchyma formation and of changes in root architecture. Moreover, we use modelling of internal aeration to demonstrate the beneficial effect of increasing cortex-to-stele ratio on sustaining root growth in waterlogged soils. We know the genes for some of the beneficial traits, and the next step is to manipulate these genes in breeding in order to enhance the flood tolerance of our crops.
PMID: 32045027
New Phytol , IF:8.512 , 2020 Feb , V225 (3) : P1049-1052 doi: 10.1111/nph.16203
Auxin guides roots to avoid obstacles during gravitropic growth.
Institute of Science and Technology (IST) Austria, 3400, Klosterneuburg, Austria.
PMID: 31603260
New Phytol , IF:8.512 , 2020 Feb , V225 (4) : P1545-1561 doi: 10.1111/nph.16244
Dual regulation of xylem formation by an auxin-mediated PaC3H17-PaMYB199 module in Populus.
Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.; College of Resources and Environment, Qingdao Agricultural University, Qingdao, 266109, China.; State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China.; University of the Chinese Academy of Sciences, Beijing, 100049, China.; National Key Laboratory of Plant Molecular Genetics and Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China.; College of Agronomy, Qingdao Agricultural University, Qingdao, 266109, China.
Wood (secondary xylem) formation in tree species is dependent on auxin-mediated vascular cambium activity in stems. However, the complex regulatory networks underlying xylem formation remain elusive. Xylem development in Populus was characterized based on microscopic observations of stem sections in transgenic plants. Transcriptomic, quantitative real-time PCR, chromatin immunoprecipitation PCR, and electrophoretic mobility shift assay analyses were conducted to identify target genes involved in xylem development. Yeast two-hybrid, pull-down, bimolecular fluorescence complementation, and co-immunoprecipitation assays were used to validate protein-protein interactions. PaC3H17 and its target PaMYB199 were found to be predominantly expressed in the vascular cambium and developing secondary xylem in Populus stems and play opposite roles in controlling cambial cell proliferation and secondary cell wall thickening through an overlapping pathway. Further, PaC3H17 interacts with PaMYB199 to form a complex, attenuating PaMYB199-driven suppression of its xylem targets. Exogenous auxin application enhances the dual control of the PaC3H17-PaMYB199 module during cambium division, thereby promoting secondary cell wall deposition. Dual regulation of xylem formation by an auxin-mediated PaC3H17-PaMYB199 module represents a novel regulatory mechanism in Populus, increasing our understanding of the regulatory networks involved in wood formation.
PMID: 31596964
New Phytol , IF:8.512 , 2020 Feb , V225 (4) : P1606-1617 doi: 10.1111/nph.16231
Two tonoplast proton pumps function in Arabidopsis embryo development.
School of Life Sciences and Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China.; Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.; School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 200032, Shanghai, China.; Department of Biology, Tokyo Gakugei University, 184-8501, Koganei-shi, Japan.
Two types of tonoplast proton pumps, H(+) -pyrophosphatase (V-PPase) and the H(+) -ATPase (V-ATPase), establish the proton gradient that powers molecular traffic across the tonoplast thereby facilitating turgor regulation and nutrient homeostasis. However, how proton pumps regulate development remains unclear. In this study, we investigated the function of two types of proton pumps in Arabidopsis embryo development and pattern formation. While disruption of either V-PPase or V-ATPase had no obvious effect on plant embryo development, knocking out both resulted in severe defects in embryo pattern formation from the early stage. While the first division in wild-type zygote was asymmetrical, a nearly symmetrical division occurred in the mutant, followed by abnormal pattern formation at all stages of embryo development. The embryonic defects were accompanied by dramatic differences in vacuole morphology and distribution, as well as disturbed localisation of PIN1. The development of mutant cotyledons and root, and the auxin response of mutant seedlings supported the hypothesis that mutants lacking tonoplast proton pumps were defective in auxin transport and distribution. Taking together, we proposed that two tonoplast proton pumps are required for vacuole morphology and PIN1 localisation, thereby controlling vacuole and auxin-related developmental processes in Arabidopsis embryos and seedlings.
PMID: 31569267
New Phytol , IF:8.512 , 2020 Feb , V225 (3) : P1261-1272 doi: 10.1111/nph.16213
ULTRAPETALA1 maintains Arabidopsis root stem cell niche independently of ARABIDOPSIS TRITHORAX1.
Laboratorio de Genetica Molecular, Epigenetica, Desarrollo y Evolucion de Plantas, Instituto de Ecologia, Universidad Nacional Autonoma de Mexico, 3er Circuito Ext. Junto a J. Botanico, Ciudad Universitaria, UNAM, Mexico City, CdMex, 04510, Mexico.; Centro de Ciencias de la Complejidad (C3), Universidad Nacional Autonoma de Mexico, Mexico City, CdMex, 04510, Mexico.
During plant development, morphogenetic processes rely on the activity of meristems. Meristem homeostasis depends on a complex regulatory network constituted by different factors and hormone signaling that regulate gene expression to coordinate the correct balance between cell proliferation and differentiation. ULTRAPETALA1, a transcriptional regulatory protein described as an Arabidopsis Trithorax group factor, has been characterized as a regulator of the shoot and floral meristems activity. Here, we highlight the role of ULTRAPETALA1 in root stem cell niche maintenance. We found that ULTRAPETALA1 is required to regulate both the quiescent center cell division rate and auxin signaling at the root tip. Furthermore, ULTRAPETALA1 regulates columella stem cell differentiation. These roles are independent of the ARABIDOPSIS TRITHORAX1, suggesting a different mechanism by which ULTRAPETALA1 can act in the root apical meristem of Arabidopsis. This work introduces a new component of the regulatory network needed for the root stem cell niche maintenance.
PMID: 31545512
New Phytol , IF:8.512 , 2020 Feb , V225 (3) : P1285-1296 doi: 10.1111/nph.16076
PIN-mediated polar auxin transport facilitates root-obstacle avoidance.
Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Korea.; Department of Functional Genomics, KRIBB School of Bioscience, University of Science and Technology, Daejeon, 34113, Korea.; Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, University of Science and Technology, Daejeon, 34113, Korea.
Plants sense mechanical stimuli to recognise nearby obstacles and change their growth patterns to adapt to the surrounding environment. When roots encounter an obstacle, they rapidly bend away from the impenetrable surface and find the edge of the barrier. However, the molecular mechanisms underlying root-obstacle avoidance are largely unknown. Here, we demonstrate that PIN-FORMED (PIN)-mediated polar auxin transport facilitates root bending during obstacle avoidance. We analysed two types of bending after roots touched barriers. In auxin receptor mutants, the rate of root movement during first bending was largely delayed. Gravity-oriented second bending was also disturbed in these mutants. The reporter assays showed that asymmetrical auxin responses occurred in the roots during obstacle avoidance. Pharmacological analysis suggested that polar auxin transport mediates local auxin accumulation. We found that PINs are required for auxin-assisted root bending during obstacle avoidance. We propose that rapid root movement during obstacle avoidance is not just a passive but an active bending completed through polar auxin transport. Our findings suggest that auxin plays a role in thigmotropism during plant-obstacle interactions.
PMID: 31336402
Curr Opin Plant Biol , IF:8.356 , 2020 Feb , V53 : P90-97 doi: 10.1016/j.pbi.2019.10.008
Growth models from a brassinosteroid perspective.
Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.; Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel. Electronic address: sigal@technion.ac.il.
Plant growth relies on interconnected hormonal pathways, their corresponding transcriptional networks and mechanical signals. This work reviews recent brassinosteroid (BR) studies and integrates them with current growth models derived from research in roots. The relevance of spatiotemporal BR signaling in the longitudinal and radial root axes and its multifaceted interaction with auxin, the impact of BR on final cell size determination and its interplay with microtubules and the cell wall are discussed. Also highlighted are emerging variations of canonical BR signaling that could function in developmental-specific context.
PMID: 31809963
Curr Opin Plant Biol , IF:8.356 , 2020 Feb , V53 : P73-79 doi: 10.1016/j.pbi.2019.10.007
Progress in understanding the role of auxin in lateral organ development in plants.
School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia. Electronic address: marcus.heisler@sydney.edu.au.; School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia. Electronic address: mary.byrne@sydney.edu.au.
Plants continuously produce lateral organs from the shoot apex such as leaves and flowers, providing an excellent opportunity to study their development. The plant hormone auxin plays a central role in this process by promoting organ formation where it accumulates due to polar auxin transport. Recently, the use of live-imaging, fine perturbation techniques and computational modelling has helped researchers make exciting progress in addressing long-standing questions on plant organogenesis, not only regarding the role of auxin in promoting growth but also on the regulation of morphogenesis and transcriptional control. In this review, we discuss a number of recent studies that address these points, with particular reference to how auxin acts in early leaf development and in leaf shape.
PMID: 31785585
Curr Opin Plant Biol , IF:8.356 , 2020 Feb , V53 : P43-49 doi: 10.1016/j.pbi.2019.10.003
Auxin signalling in growth: Schrodinger's cat out of the bag.
Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Muthgasse 18, 1190 Wien, Austria.; Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria. Electronic address: jiri.friml@ist.ac.at.
The phytohormone auxin acts as an amazingly versatile coordinator of plant growth and development. With its morphogen-like properties, auxin controls sites and timing of differentiation and/or growth responses both, in quantitative and qualitative terms. Specificity in the auxin response depends largely on distinct modes of signal transmission, by which individual cells perceive and convert auxin signals into a remarkable diversity of responses. The best understood, or so-called canonical mechanism of auxin perception ultimately results in variable adjustments of the cellular transcriptome, via a short, nuclear signal transduction pathway. Additional findings that accumulated over decades implied that an additional, presumably, cell surface-based auxin perception mechanism mediates very rapid cellular responses and decisively contributes to the cell's overall hormonal response. Recent investigations into both, nuclear and cell surface auxin signalling challenged this assumed partition of roles for different auxin signalling pathways and revealed an unexpected complexity in transcriptional and non-transcriptional cellular responses mediated by auxin.
PMID: 31760231
Curr Opin Plant Biol , IF:8.356 , 2020 Feb , V53 : P128-133 doi: 10.1016/j.pbi.2019.10.002
Square one: zygote polarity and early embryogenesis in flowering plants.
Max Planck Institute for Developmental Biology, Department of Cell Biology, Max-Planck-Ring 5, 72076 Tubingen, Germany.; Max Planck Institute for Developmental Biology, Department of Cell Biology, Max-Planck-Ring 5, 72076 Tubingen, Germany. Electronic address: martin.bayer@tuebingen.mpg.de.
In the last two decades, work on auxin signaling has helped to understand many aspects of the fundamental process underlying the specification of tissue types in the plant embryo. However, the immediate steps after fertilization including the polarization of the zygote and the initial body axis formation remained poorly understood. Valuable insight into these enigmatic processes has been gained by studying fertilization in grasses. Recent technical advances in transcriptomics of developing embryos with high spatial and temporal resolution give an emerging picture of the rapid changes of the zygotic developmental program. Together with the use of live imaging of novel fluorescent marker lines, these data are now the basis of unraveling the very first steps of the embryonic patterning process.
PMID: 31727540
Plant Biotechnol J , IF:8.154 , 2020 Feb doi: 10.1111/pbi.13360
OsmiR167a-targeted auxin response factors modulate tiller angle via fine-tuning auxin distribution in rice.
National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, China.; College of Life Sciences, Hubei University, Wuhan, China.; Institute of Rice Research, Guizhou Academy of Agricultural Sciences, Guiyang, China.; State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China.
Rice tiller angle determines plant growth density and further contributes grain production. Although a few genes have been characterized to regulate tiller angle in rice, the molecular mechanism underlying the control of tiller angle via microRNA is poorly understood. Here, we report that rice tiller angle is controlled by OsmiR167a-targeted auxin response factors OsARF12, OsARF17 and OsARF25. In the overexpression of OsMIR167a plants, the expression of OsARF12, OsARF17 and OsARF25 was severely repressed and displayed larger tiller angle as well as the osarf12/osarf17 and osarf12/ osarf25 plants. In addition, those plants showed compromised abnormal auxin distribution and less sensitive to gravity. We also demonstrate that OsARF12, OsARF17 and OsARF25 function redundantly and might be involved in HSFA2D and LAZY1-dependent asymmetric auxin distribution pathway to control rice tiller angle. Our results reveal that OsmiR167a represses its targets, OsARF12, OsARF17 and OsARF25, to control rice tiller angle by fine-tuning auxin asymmetric distribution in shoots.
PMID: 32061119
Plant Biotechnol J , IF:8.154 , 2020 Feb doi: 10.1111/pbi.13357
Rice Big Grain 1 promotes cell division to enhance organ development, stress tolerance and grain yield.
Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, ROC.; Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC.; Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan, ROC.; Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, Taiwan, ROC.; CropDesign N.V., BASF Plant Science, Nevele, Belgium.; Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, ROC.
Grain/seed yield and plant stress tolerance are two major traits that determine the yield potential of many crops. In cereals, grain size is one of the key factors affecting grain yield. Here, we identify and characterize a newly discovered gene Rice Big Grain 1 (RBG1) that regulates grain and organ development, as well as abiotic stress tolerance. Ectopic expression of RBG1 leads to significant increases in the size of not only grains but also other major organs such as roots, shoots and panicles. Increased grain size is primarily due to elevated cell numbers rather than cell enlargement. RBG1 is preferentially expressed in meristematic and proliferating tissues. Ectopic expression of RBG1 promotes cell division, and RBG1 co-localizes with microtubules known to be involved in cell division, which may account for the increase in organ size. Ectopic expression of RBG1 also increases auxin accumulation and sensitivity, which facilitates root development, particularly crown roots. Moreover, overexpression of RBG1 up-regulated a large number of heat-shock proteins, leading to enhanced tolerance to heat, osmotic and salt stresses, as well as rapid recovery from water-deficit stress. Ectopic expression of RBG1 regulated by a specific constitutive promoter, GOS2, enhanced harvest index and grain yield in rice. Taken together, we have discovered that RBG1 regulates two distinct and important traits in rice, namely grain yield and stress tolerance, via its effects on cell division, auxin and stress protein induction.
PMID: 32034845
Plant Biotechnol J , IF:8.154 , 2020 Feb doi: 10.1111/pbi.13356
Genomic signatures and candidate genes of lint yield and fibre quality improvement in Upland cotton in Xinjiang.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China.; Zhejiang Provincial Key Laboratory of Crop Genetic Resources, Institute of Crop Science, Plant Precision Breeding Academy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.; Key Laboratory of China Northwestern Inland Region, Ministry of Agriculture, Cotton Research Institute, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi, China.; Esquel Group, Wanchai, Hong Kong, China.
Xinjiang has been the largest and highest yield cotton production region not only in China, but also in the world. Improvements in Upland cotton cultivars in Xinjiang have occurred via pedigree selection and/or crossing of elite alleles from the former Soviet Union and other cotton producing regions of China. But it is unclear how genomic constitutions from foundation parents have been selected and inherited. Here, we deep-sequenced seven historic foundation parents, comprising four cultivars introduced from the former Soviet Union (108capital EF, Cyrillic, C1470, 611capital BE, Cyrillic and KK1543) and three from United States and Africa (DPL15, STV2B and UGDM), and re-sequenced sixty-nine Xinjiang modern cultivars. Phylogenetic analysis of more than 2 million high-quality single nucleotide polymorphisms allowed their classification two groups, suggesting that Xinjiang Upland cotton cultivars were not only spawned from 108capital EF, Cyrillic, C1470, 611capital BE, Cyrillic and KK1543, but also had a close kinship with DPL15, STV2B and UGDM. Notably, identity-by-descent (IBD) tracking demonstrated that the former Soviet Union cultivars have made a huge contribution to modern cultivar improvement in Xinjiang. A total of 156 selective sweeps were identified. Among them, apoptosis-antagonizing transcription factor gene (GhAATF1) and mitochondrial transcription termination factor family protein gene (GhmTERF1) were highly involved in the determination of lint percentage. Additionally, the auxin response factor gene (GhARF3) located in inherited IBD segments from 108capital EF, Cyrillic and 611capital BE, Cyrillic was highly correlated with fibre quality. These results provide an insight into the genomics of artificial selection for improving cotton production and facilitate next-generation precision breeding of cotton and other crops.
PMID: 32030869
Plant Biotechnol J , IF:8.154 , 2020 Feb doi: 10.1111/pbi.13353
Indole-3-acetate beta-glucosyltransferase OsIAGLU regulates seed vigour through mediating crosstalk between auxin and abscisic acid in rice.
The Laboratory of Seed Science and Technology, Guangdong Key Laboratory of Plant Molecular Breeding, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.; College of Agriculture and Biology, Zhongkai University of Agriculture and Engineering, Guangzhou, China.
Seed vigour is an important trait for direct seeding in rice. In this study, indole-3-acetate beta-glucosyltransferase OsIAGLU was cloned in rice, and its roles on seed vigour were mainly investigated. Disruption of OsIAGLU resulted in low seed vigour in rice. Quantitative RT-PCR analysis showed that the expressions of OsIAGLU were relatively higher in the late developing and the early germinating seeds and were significantly induced by indole-3-acetic acid (IAA) and abscisic acid (ABA). Transcriptome analysis revealed that the IAA- and ABA-related genes were involved in the OsIAGLU regulation of seed vigour in rice. The higher levels of free IAA and ABA were identified in germinating seeds of osiaglu mutants compared to wild-type (WT) plants. When treated with exogenous IAA and ABA, the osiaglu mutants and WT plants showed sensitivity to ABA while not IAA, but the exogenous IAA amplified ABA-induced reduction of seed vigour in rice. The continuously higher expressions of ABA-INSENSITIVE 3 (OsABI3) and OsABI5 occurred in germinating seeds of osiaglu mutants compared to WT plants. The regulation of seed vigour by OsIAGLU might be through modulating IAA and ABA levels to alert OsABIs expression in germinating seeds in rice. Based on analysis of single-nucleotide polymorphism data of rice accessions, two haplotypes of OsIAGLU that positively correlated with seed vigour were identified in indica accessions. This study provides important insights into the roles of OsIAGLU on seed vigour and facilitates the practical use of OsIAGLU in rice breeding.
PMID: 32012429
Plant Biotechnol J , IF:8.154 , 2020 Feb , V18 (2) : P429-442 doi: 10.1111/pbi.13209
OsNAC2 integrates auxin and cytokinin pathways to modulate rice root development.
Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China.; State Key Laboratory of Genetic Engineering, Institute of Genetics, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, China.; Institute of Rice Research, Sichuan Agricultural University, Chengdu, China.; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China.; Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.; The Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, China.
The rice root system is important for growth. The crosstalk between auxin and cytokinin mediates root initiation and elongation. However, it remains unclear how the transcriptional network upstream of the auxin and cytokinin signalling pathways determines root development. Here, we observed that the knockdown of OsNAC2, which encodes a NAC transcription factor, increased the primary root length and the number of crown roots. OsNAC2 predominantly expressed in primary root tips, crown roots and lateral root primordia, implying it influences root development. Molecular analyses revealed that the expressions of auxin- and cytokinin-responsive genes were affected in OsNAC2-overexpressing (OsNAC2-OX; ON7 and ON11), RNA interference (OsNAC2-RNAi; RNAi25 and RNAi31) and CRISPR/Cas9 plants. Additionally, OsNAC2 can directly bind to the promoters of IAA inactivation-related genes (GH3.6 and GH3.8), an IAA signalling-related gene (OsARF25), and a cytokinin oxidase gene (OsCKX4). Furthermore, genetic analysis of ON11/osgh3.6 and RNAi31/osckx4 homozygote confirmed that OsCKX4 and OsGH3.6 functioned downstream of OsNAC2. The mRNA levels of CROWN ROOTLESS (CRL) genes and cyclin-dependent protein kinase (CDK) genes increased in OsNAC2-RNAi and OsNAC2-cas9 lines while reduced in OsNAC2-OX lines. Thus, we describe that OsNAC2 functions as an upstream integrator of auxin and cytokinin signals that affect CRL and CDK production to regulate cell division during root development. This novel auxin-OsNAC2-cytokinin model should provide a new insight into the understanding of NAC TFs and crosstalk of auxin and cytokinin pathway, and can be potentially applied in agriculture to enhance rice yields by genetic approaches.
PMID: 31389120
Plant Biotechnol J , IF:8.154 , 2020 Feb , V18 (2) : P568-580 doi: 10.1111/pbi.13224
A systematic dissection of the mechanisms underlying the natural variation of silique number in rapeseed (Brassica napus L.) germplasm.
Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan, China.; Crop Research Institute, Jiangxi Academy of Agricultural Sciences, Nanchang, China.; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.; Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India.
Silique number is the most important component of yield in rapeseed (Brassica napus L.). To dissect the mechanism underlying the natural variation of silique number in rapeseed germplasm, a series of studies were performed. A panel of 331 core lines was employed to genome-wide association study (GWAS), and 27 loci (including 20 novel loci) were identified. The silique number difference between the more- and fewer-silique lines can be attributed to the accumulative differences in flower number and silique setting rate. Each of them accounted for 75.2% and 24.8%, respectively. The silique number was highly associated with the total photosynthesis and biomass. Microscopic analysis showed that the difference between extremely more- and fewer-silique lines normally occurred at the amount of flower bud but not morphology. Transcriptome analysis of shoot apical meristem (SAM) suggested that most of enriched groups were associated with the auxin biosynthesis/metabolism, vegetative growth and nutrition/energy accumulation. By integrating GWAS and RNA-seq results, six promising candidate genes were identified, and some of them were related to biomass accumulation. In conclusion, the natural variation of silique number is largely affected by the biomass and nutrition accumulation, which essentially reflects the positive regulatory relationship between the source and sink. Our study provides a comprehensive and systematic explanation for natural variation of silique number in rapeseed, which provides a foundation for its improvement.
PMID: 31368615
Plant Biotechnol J , IF:8.154 , 2020 Feb , V18 (2) : P526-539 doi: 10.1111/pbi.13221
AKR2A participates in the regulation of cotton fibre development by modulating biosynthesis of very-long-chain fatty acids.
Zhejiang Academy of Agricultural Sciences, Hangzhou, China.; State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China.; National Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China.; Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
The biosynthesis of very-long-chain fatty acids (VLCFAs) and their transport are required for fibre development. However, whether other regulatory factors are involved in this process is unknown. We report here that overexpression of an Arabidopsis gene ankyrin repeat-containing protein 2A (AKR2A) in cotton promotes fibre elongation. RNA-Seq analysis was employed to elucidate the mechanisms of AKR2A in regulating cotton fibre development. The VLCFA content and the ratio of VLCFAs to short-chain fatty acids increased in AKR2A transgenic lines. In addition, AKR2A promotes fibre elongation by regulating ethylene and synergizing with the accumulation of auxin and hydrogen peroxide. Analysis of RNA-Seq data indicates that AKR2A up-regulates transcript levels of genes involved in VLCFAs' biosynthesis, ethylene biosynthesis, auxin and hydrogen peroxide signalling, cell wall and cytoskeletal organization. Furthermore, AKR2A interacted with KCS1 in Arabidopsis both in vitro and in vivo. Moreover, the VLCFA content and the ratio of VLCFAs to short-chain fatty acids increased significantly in seeds of AKR2A-overexpressing lines and AKR2A/KCS1 co-overexpressing lines, while AKR2A mutants are the opposite trend. Our results uncover a novel cotton fibre growth mechanism by which the critical regulator AKR2A promotes fibre development via activating hormone signalling cascade by mediating VLCFA biosynthesis. This study provides a potential candidate gene for improving fibre yield and quality through genetic engineering.
PMID: 31350932
Plant Biotechnol J , IF:8.154 , 2020 Feb , V18 (2) : P457-469 doi: 10.1111/pbi.13211
The peu-miR160a-PeARF17.1/PeARF17.2 module participates in the adventitious root development of poplar.
Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China.; College of Forestry, Nanjing Forestry University, Nanjing, China.; Jiangxi Academy of Forestry, Nanchang, Jiangxi, China.
Deep roots give rise to flourishing leaves, and the two complement each other. However, the genetic mechanisms underlying adventitious rooting for forest trees have remained elusive. In this study, we verified that peu-miR160a targets six poplar genes AUXIN RESPONSE FACTORS (ARFs), PeARF10.1, PeARF16.1, PeARF16.2, PeARF16.3, PeARF17.1 and PeARF17.2, using 5'RLM-RACE. Interaction experiments with peu-miR160a and PeARFs in poplar protoplasts further confirmed that peu-miR160a targets and negatively regulates the six PeARFs. Peu-miR160a and its target genes exhibited obvious temporal expression in different stages of adventitious root development, and they could also be induced by IAA and abscisic acid. Peu-miR160a-overexpressing lines exhibited a significant shortening of adventitious root length, an increase in the number of lateral roots, severe dwarfing and shortened internodes. In addition, the overexpression of PeARF17.1 or mPeARF17.2 (peu-miR160a-resistant version of PeARF17.2) significantly increased the number of adventitious roots. Furthermore, PeARF17.1-overexpressing lines had multiple branches with no visible trunk, although the adventitious root length of the PeARF17.1-overexpressing lines was significantly increased. Our findings reveal that the peu-miR160a - PeARF17.1/PeARF17.2 module is an important regulator involved in the development of the adventitious roots of poplar.
PMID: 31314168
Elife , IF:7.08 , 2020 Feb , V9 doi: 10.7554/eLife.54740
Genetic analysis of the Arabidopsis TIR1/AFB auxin receptors reveals both overlapping and specialized functions.
Section of Cell and Developmental Biology, University of California San Diego, La Jolla, United States.; Plant Molecular and Cellular Biology Laboratory and Integrative Biology Laboratory, Salk Institute for Biological Studies, La Jolla, United States.; Plant and Crop Sciences, School of Biosciences, University of Nottingham, Nottingham, United Kingdom.
The TIR1/AFB auxin co-receptors mediate diverse responses to the plant hormone auxin. The Arabidopsis genome encodes six TIR1/AFB proteins representing three of the four clades that were established prior to angiosperm radiation. To determine the role of these proteins in plant development we performed an extensive genetic analysis involving the generation and characterization of all possible multiply-mutant lines. We find that loss of all six TIR1/AFB proteins results in early embryo defects and eventually seed abortion, and yet a single wild-type allele of TIR1 or AFB2 is sufficient to support growth throughout development. Our analysis reveals extensive functional overlap between even the most distantly related TIR1/AFB genes except for AFB1. Surprisingly, AFB1 has a specialized function in rapid auxin-dependent inhibition of root growth and early phase of root gravitropism. This activity may be related to a difference in subcellular localization compared to the other members of the family.
PMID: 32067636
Plant Physiol , IF:6.902 , 2020 Feb , V182 (2) : P933-948 doi: 10.1104/pp.19.00917
MADS78 and MADS79 Are Essential Regulators of Early Seed Development in Rice.
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583.; Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588.; School of Biological Science, University of Nebraska, Lincoln, Nebraska 68588.; Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 hwalia2@unl.edu.
MADS box transcription factors (TFs) are subdivided into type I and II based on phylogenetic analysis. The type II TFs regulate floral organ identity and flowering time, but type I TFs are relatively less characterized. Here, we report the functional characterization of two type I MADS box TFs in rice (Oryza sativa), MADS78 and MADS79 Transcript abundance of both these genes in developing seed peaked at 48 h after fertilization and was suppressed by 96 h after fertilization, corresponding to syncytial and cellularized stages of endosperm development, respectively. Seeds overexpressing MADS78 and MADS 79 exhibited delayed endosperm cellularization, while CRISPR-Cas9-mediated single knockout mutants showed precocious endosperm cellularization. MADS78 and MADS 79 were indispensable for seed development, as a double knockout mutant failed to make viable seeds. Both MADS78 and 79 interacted with MADS89, another type I MADS box, which enhances nuclear localization. The expression analysis of Fie1, a rice FERTILIZATION-INDEPENDENT SEED-POLYCOMB REPRESSOR COMPLEX2 component, in MADS78 and 79 mutants and vice versa established an antithetical relation, suggesting that Fie1 could be involved in negative regulation of MADS78 and MADS 79 Misregulation of MADS78 and MADS 79 perturbed auxin homeostasis and carbon metabolism, as evident by misregulation of genes involved in auxin transport and signaling as well as starch biosynthesis genes causing structural abnormalities in starch granules at maturity. Collectively, we show that MADS78 and MADS 79 are essential regulators of early seed developmental transition and impact both seed size and quality in rice.
PMID: 31818903
Plant Physiol , IF:6.902 , 2020 Feb , V182 (2) : P1039-1051 doi: 10.1104/pp.19.01144
Switching the Direction of Stem Gravitropism by Altering Two Amino Acids in AtLAZY1.
Department of Botany, University of Wisconsin, 430 Lincoln Drive, Madison, Wisconsin 53706.; Department of Botany, University of Wisconsin, 430 Lincoln Drive, Madison, Wisconsin 53706 spalding@wisc.edu.
From germination to flowering, gravity influences plant growth and development. A rice (Oryza sativa) mutant with a distinctly prostrate growth habit led to the discovery of a gene category that participates in the shaping of plant form by gravity. Each so-called LAZY gene includes five short regions of conserved sequence. The importance of each of these regions in the LAZY1 gene of Arabidopsis (Arabidopsis thaliana; AtLAZY1) was tested by mutating each region and measuring how well transgenic expression of the resulting protein variant rescued the large inflorescence branch angle of an atlazy1 mutant. The effect of each alteration on subcellular localization was also determined. Region I was required for AtLAZY1 to reside at the plasma membrane, which is necessary for its function. Mutating region V severely disrupted function without affecting subcellular localization. Regions III and IV could be mutated without large impact on function or localization. Altering region II with two conservative amino acid substitutions (L92A/I94A) had the profound effect of switching shoot gravity responses from negative (upward bending) to positive (downward bending), resulting in a "weeping" inflorescence phenotype. Mechanical weakness of the stem was ruled out as an explanation for the downward bending. Instead, experiments demonstrated that the L92A/I94A change to AtLAZY1 reversed the auxin gradient normally established across stems by the gravity-sensing mechanism. This discovery opens up new avenues for studying how auxin gradients form across organs and new approaches for engineering plant architecture for agronomic and other practical purposes.
PMID: 31818902
Plant Physiol , IF:6.902 , 2020 Feb , V182 (2) : P892-907 doi: 10.1104/pp.19.00928
Exogenous Auxin Induces Transverse Microtubule Arrays Through TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX Receptors.
Department of Biology, Indiana University, Bloomington, Indiana 47405.; Department of Biology, Indiana University, Bloomington, Indiana 47405 SiShaw@Indiana.edu.
Auxin plays a central role in controlling plant cell growth and morphogenesis. Application of auxin to light-grown seedlings elicits both axial growth and transverse patterning of the cortical microtubule cytoskeleton in hypocotyl cells. Microtubules respond to exogenous auxin within 5 min, although repatterning of the array does not initiate until 30 min after application and is complete by 2 h. To examine the requirements for auxin-induced microtubule array patterning, we used an Arabidopsis (Arabidopsis thaliana) double auxin f-box (afb) receptor mutant, afb4-8 afb5-5, that responds to conventional auxin (indole-3-acetic acid) but has a strongly diminished response to the auxin analog, picloram. We show that 5 microm picloram induces immediate changes to microtubule density and later transverse microtubule patterning in wild-type plants, but does not cause microtubule array reorganization in the afb4-8 afb5-5 mutant. Additionally, a dominant mutant (axr2-1) for the auxin coreceptor AUXIN RESPONSIVE2 (AXR2) was strongly suppressed for auxin-induced microtubule array reorganization, providing additional evidence that auxin functions through a transcriptional pathway for transverse patterning. We observed that brassinosteroid application mimicked the auxin response, showing both early and late microtubule array effects, and induced transverse patterning in the axr2-1 mutant. Application of auxin to the brassinosteroid synthesis mutant, diminuto1, induced transverse array patterning but did not produce significant axial growth. Thus, exogenous auxin induces transverse microtubule patterning through the TRANSPORT INHIBITOR 1/AUXIN F-BOX (TIR1/AFB) transcriptional pathway and can act independently of brassinosteroids.
PMID: 31767691
Environ Pollut , IF:6.792 , 2020 Feb , V257 : P113516 doi: 10.1016/j.envpol.2019.113516
The mechanism of root growth inhibition by the endocrine disruptor bisphenol A (BPA).
Department of Molecular Biology, Sejong University, Seoul, 143-747, South Korea; Department of Bioindustry and Bioresource Engineering, Sejong University, Seoul, 143-747, South Korea; The Plant Engineering Research Institute, Sejong University, Seoul, 143-747, South Korea.; Cranfield Soil and Agrifood Institute, Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UK.; College of Pharmacy, Hanyang University, Ansan, Gyeonggi-do 15588, South Korea.; Department of Molecular Biology, Sejong University, Seoul, 143-747, South Korea; Department of Bioindustry and Bioresource Engineering, Sejong University, Seoul, 143-747, South Korea; The Plant Engineering Research Institute, Sejong University, Seoul, 143-747, South Korea. Electronic address: sbhwang@sejong.ac.kr.
Bisphenol A (BPA) is a harmful environmental contaminant acting as an endocrine disruptor in animals, but it also affects growth and development in plants. Here, we have elucidated the functional mechanism of root growth inhibition by BPA in Arabidopsis thaliana using mutants, reporter lines and a pharmacological approach. In response to 10ppm BPA, fresh weight and main root length were reduced, while auxin levels increased. BPA inhibited root growth by reducing root cell length in the elongation zone by suppressing expansin expression and by decreasing the length of the meristem zone by repressing cell division. The inhibition of cell elongation and cell division was attributed to the enhanced accumulation/redistribution of auxin in the elongation zone and meristem zone in response to BPA. Correspondingly, the expressions of most auxin biosynthesis and transporter genes were enhanced in roots by BPA. Taken together, it is assumed that the endocrine disruptor BPA inhibits primary root growth by inhibiting cell elongation and division through auxin accumulation/redistribution in Arabidopsis. This study will contribute to understanding how BPA affects growth and development in plants.
PMID: 31733969
Plant Cell Environ , IF:6.362 , 2020 Feb , V43 (2) : P358-373 doi: 10.1111/pce.13667
Endophytic fungus Falciphora oryzae promotes lateral root growth by producing indole derivatives after sensing plant signals.
Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.; Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, 310058, China.
The endophytic fungus Falciphora oryzae was initially isolated from wild rice (Oryza granulata) and colonizes many crop species and promotes plant growth. However, the molecular mechanisms underlying F. oryzae-mediated growth promotion are still unknown. We found that F. oryzae was able to colonize Arabidopsis thaliana. The most dramatic change after F. oryzae inoculation was observed in the root architecture, as evidenced by increased lateral root growth but reduced primary root length, similar to the effect of auxin, a significant plant growth hormone. The expression of genes responsible for auxin biosynthesis, transport, and signalling was regulated in Arabidopsis roots after F. oryzae cocultivation. Indole derivatives were detected at significantly higher levels in liquid media after cocultivation compared with separate cultivation of Arabidopsis and F. oryzae. Consistently, the expression of indole biosynthetic genes was highly upregulated in F. oryzae upon treatment with Arabidopsis exudates. Global analysis of Arabidopsis gene expression at the early stage after F. oryzae cocultivation suggested that signals were exchanged to initiate Arabidopsis-F. oryzae interactions. All these results suggest that signalling molecules from Arabidopsis roots are perceived by F. oryzae and induce the biosynthesis of indole derivatives in F. oryzae, consequently stimulating Arabidopsis lateral root growth.
PMID: 31675439
J Exp Bot , IF:5.908 , 2020 Feb , V71 (4) : P1418-1433 doi: 10.1093/jxb/erz508
Seed comparative genomics in three coffee species identify desiccation tolerance mechanisms in intermediate seeds.
IRD, Universite Montpellier, UMR DIADE, Montpellier, France.; Universite de La Reunion, UMR PVBMT, Ligne Paradis, Saint Pierre, France.; MGX-Montpellier GenomiX, c/o Institut de Genomique Fonctionnelle, Montpellier Cedex 5, France.; CIRAD, UMR QUALISUD, Ligne Paradis, Reunion, France.; BPMP, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, Montpellier, France.
In contrast to desiccation-tolerant 'orthodox' seeds, so-called 'intermediate' seeds cannot survive complete drying and are short-lived. All species of the genus Coffea produce intermediate seeds, but they show a considerable variability in seed desiccation tolerance (DT), which may help to decipher the molecular basis of seed DT in plants. We performed a comparative transcriptome analysis of developing seeds in three coffee species with contrasting desiccation tolerance. Seeds of all species shared a major transcriptional switch during late maturation that governs a general slow-down of metabolism. However, numerous key stress-related genes, including those coding for the late embryogenesis abundant protein EM6 and the osmosensitive calcium channel ERD4, were up-regulated during DT acquisition in the two species with high seed DT, C. arabica and C. eugenioides. By contrast, we detected up-regulation of numerous genes involved in the metabolism, transport, and perception of auxin in C. canephora seeds with low DT. Moreover, species with high DT showed a stronger down-regulation of the mitochondrial machinery dedicated to the tricarboxylic acid cycle and oxidative phosphorylation. Accordingly, respiration measurements during seed dehydration demonstrated that intermediate seeds with the highest DT are better prepared to cease respiration and avoid oxidative stresses.
PMID: 31790120
J Exp Bot , IF:5.908 , 2020 Feb , V71 (4) : P1459-1474 doi: 10.1093/jxb/erz520
GABA negatively regulates adventitious root development in poplar.
State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry and Grassland Administration, Research Institute of Forestry Research, Chinese Academy of Forestry, Beijing, China.; Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.; Risk Assessment Laboratory for Bee Products, Quality and Safety of Ministry of Agriculture, Beijing, China.; Research Institute of Forest Ecology, Environment and Protection, Key Laboratory of Forest Ecology and Environment of State Forestry and Grassland Administration, Chinese Academy of Forestry, Beijing, China.
gamma-Aminobutyric acid (GABA) influences plant growth, but little is known about how this metabolite regulates adventitious root (AR) development. Here, we investigate the effects of GABA on ARs using poplar lines overexpressing glutamate decarboxilase 2 (GAD2) and by treating poplar stem cuttings with exogenous GABA or vigabatrin (VGB; a specific GABA transaminase inhibitor). Endogenous GABA accumulation not only inhibited AR growth, but it also suppressed or delayed AR formation. Anatomical observations revealed that the GABA and VGB treatments resulted in a 1 d delay in the formation of AR primordia and the appearance of ARs. This delay coincided with changes in primary metabolism, including transient increases in hexose and amino acid levels. GABA-dependent changes in the expression of genes related to hormone synthesis and signalling, as well as analysis of hormone levels revealed that ethylene-dependent pathways were decreased at the earliest stage of AR formation. In contrast, auxin and abscisic acid were increased at 1-5 d as well as GA4 over a 5 d period of AR formation. These results demonstrate that GABA plays a crucial role in AR development. Evidence is presented demonstrating that GABA can interact with hormone-related pathways as well as carbon/nitrogen metabolism. These findings also elucidate the functions of GABA in plant development.
PMID: 31740934
J Exp Bot , IF:5.908 , 2020 Feb , V71 (4) : P1562-1573 doi: 10.1093/jxb/erz510
The Medicago truncatula PIN2 auxin transporter mediates basipetal auxin transport but is not necessary for nodulation.
Division of Plant Science, Research School of Biology, Australian National University, Canberra, Australia.; Noble Research Institute LLC, Ardmore, OK, USA.; School of Life Sciences, Lanzhou University, Lanzhou, China.
The development of root nodules leads to an increased auxin response in early nodule primordia, which is mediated by changes in acropetal auxin transport in some legumes. Here, we investigated the role of root basipetal auxin transport during nodulation. Rhizobia inoculation significantly increased basipetal auxin transport in both Medicago truncatula and Lotus japonicus. In M. truncatula, this increase was dependent on functional Nod factor signalling through NFP, NIN, and NSP2, as well as ethylene signalling through SKL. To test whether increased basipetal auxin transport is required for nodulation, we examined a loss-of-function mutant of the M. truncatula PIN2 gene. The Mtpin2 mutant exhibited a reduction in basipetal auxin transport and an agravitropic phenotype. Inoculation of Mtpin2 roots with rhizobia still led to a moderate increase in basipetal auxin transport, but the mutant nodulated normally. No clear differences in auxin response were observed during nodule development. Interestingly, inoculation of wild-type roots increased lateral root numbers, whereas inoculation of Mtpin2 mutants resulted in reduced lateral root numbers compared with uninoculated roots. We conclude that the MtPIN2 auxin transporter is involved in basipetal auxin transport, that its function is not essential for nodulation, but that it plays an important role in the control of lateral root development.
PMID: 31738415
J Exp Bot , IF:5.908 , 2020 Feb , V71 (4) : P1350-1362 doi: 10.1093/jxb/erz410
Stem cell fate in hypoxic root apical meristems is influenced by phytoglobin expression.
Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada.; Department of Botany, Faculty of Science, Tanta University, Tanta, Egypt.; Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada.
Root survival to flooding-induced hypoxic stress is dependent upon maintaining the functionality of the root apical meristem quiescent center (QC), a process that is governed by the basipetal flow of auxin leading to the formation of an auxin maximum, which is needed for the establishment of a highly oxidized environment specifying the QC niche. Perturbations in auxin flow and distribution along the root profile occurring during hypoxia can shift the redox state of the QC towards a more reduced environment, leading to the activation of the QC, degradation of the meristem, and root abortion. The maize phytoglobin gene ZmPgb1.1 is involved in minimizing these damaging effects during hypoxia in processes that result in sustaining the PIN-mediated auxin maximum and an oxidized environment in the QC. The oxidized environment is accomplished by maintaining the activity of redox enzymes oxidizing ascorbate and glutathione. These events, compromised in QCs suppressing ZmPgb1.1, ensure the functionality of the QC and root meristems under conditions of low oxygen, resulting in stable root performance.
PMID: 31541257
Development , IF:5.611 , 2020 Feb , V147 (3) doi: 10.1242/dev.181446
The dynamic nature and regulation of the root clock.
State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, People's Republic of China.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, B-9052 Ghent, Belgium.; VIB-UGent Center for Plant Systems Biology, Technologiepark 71, B-9052 Ghent, Belgium.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, B-9052 Ghent, Belgium tom.beeckman@psb.vib-ugent.be.
Plants explore the soil by continuously expanding their root system, a process that depends on the production of lateral roots (LRs). Sites where LRs can be produced are specified in the primary root axis through a pre-patterning mechanism, determined by a biological clock that is coordinated by temporal signals and positional cues. This 'root clock' generates an oscillatory signal that is translated into a developmental cue to specify a set of founder cells for LR formation. In this Review, we summarize recent findings that shed light on the mechanisms underlying the oscillatory signal and discuss how a periodic signal contributes to the conversion of founder cells into LR primordia. We also provide an overview of the phases of the root clock that may be influenced by endogenous factors, such as the plant hormone auxin, and by exogenous environmental cues. Finally, we discuss additional aspects of the root-branching process that act independently of the root clock.
PMID: 32014866
PLoS Genet , IF:5.174 , 2020 Feb , V16 (2) : Pe1008044 doi: 10.1371/journal.pgen.1008044
PRH1 mediates ARF7-LBD dependent auxin signaling to regulate lateral root development in Arabidopsis thaliana.
The Key Laboratory of the Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China.
The development of lateral roots in Arabidopsis thaliana is strongly dependent on signaling directed by the AUXIN RESPONSE FACTOR7 (ARF7), which in turn activates LATERAL ORGAN BOUNDARIES DOMAIN (LBD) transcription factors (LBD16, LBD18 and LBD29). Here, the product of PRH1, a PR-1 homolog annotated previously as encoding a pathogen-responsive protein, was identified as a target of ARF7-mediated auxin signaling and also as participating in the development of lateral roots. PRH1 was shown to be strongly induced by auxin treatment, and plants lacking a functional copy of PRH1 formed fewer lateral roots. The transcription of PRH1 was controlled by the binding of both ARF7 and LBDs to its promoter region.
PMID: 32032352
Nanotoxicology , IF:4.925 , 2020 Feb , V14 (1) : P127-144 doi: 10.1080/17435390.2019.1678693
Copper oxide nanoparticles alter cellular morphology via disturbing the actin cytoskeleton dynamics in Arabidopsis roots.
Biomass Energy Center for Arid and Semi-Arid Lands, College of Life Sciences, Northwest a&F University, Yangling, Shaanxi, China.; School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, China.
Copper oxide nanoparticles (CuO NPs) have severe nano-toxic effects on organisms. Limited data is available on influence of CuO NPs on plant cells. Here, the molecular mechanisms involved in the toxicity of CuO NPs are studied. Exposure to CuO NPs significantly increased copper content in roots (0.062-0.325 mg/g FW), but CuO NPs translocation rates from root to shoot were low (1.1-2.8%). Presented data were significant at p < 0.05 compared to control. CuO NPs inhibited longitudinal growth and promoted transverse growth in root tip cells. However, CuO NPs did not affect the leaf cells, implying that the transfer ability of CuO NPs was weak, and toxicity mainly affected roots. CuO NPs can conjugate with actin protein. The actin cytoskeleton experienced reorganization in the presence of CuO NPs. The longitudinal filamentous actin (F-actin) decreased, and the transverse F-actin increased. CuO NPs inhibited actin polymerization and promoted depolymerization. The behavior of individual F-actin was at steady state with time-lapse under CuO NPs treatment by time-lapse reflection fluorescence (TIRF) microscopy. The growth rate of actin filaments was weakened by CuO NPs. CuO NPs disturbed the subcellular localization of PINs and the gradient of auxin distribution in root tips in an actin-dependent manner. In conclusion, CuO NPs conjugated with actin and disturbed F-actin dynamics, triggering abnormal cell growth in the root tip, and findings provide theoretical basis for further study nano-toxicity in plants.
PMID: 31684790
Ecotoxicol Environ Saf , IF:4.872 , 2020 Feb , V189 : P109989 doi: 10.1016/j.ecoenv.2019.109989
Distinct redox signalling and nickel tolerance in Brassica juncea and Arabidopsis thaliana.
Department of Plant Biology, University of Szeged, Kozep fasor 52, H-6726, Szeged, Hungary. Electronic address: kolzsu@bio.u-szeged.hu.; Department of Plant Biology, University of Szeged, Kozep fasor 52, H-6726, Szeged, Hungary; Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary. Electronic address: olah.dora18@citromail.hu.; Department of Plant Biology, University of Szeged, Kozep fasor 52, H-6726, Szeged, Hungary. Electronic address: molnara@bio.u-szeged.hu.; Department of Plant Biology, University of Szeged, Kozep fasor 52, H-6726, Szeged, Hungary. Electronic address: szoszo@bio.u-szeged.hu.; Department of Plant Biology, University of Szeged, Kozep fasor 52, H-6726, Szeged, Hungary. Electronic address: erdei@bio.u-szeged.hu.; Department of Plant Biology, University of Szeged, Kozep fasor 52, H-6726, Szeged, Hungary. Electronic address: aordog@bio.u-szeged.hu.
Despite of its essentiality, nickel (Ni) in excess is toxic for plants partly due to the overproduction of reactive oxygen species (ROS) and the consequent increase in oxidative stress signalling. However, in Ni-stressed plants little is known about the signal transduction of reactive nitrogen species (RNS) and protein tyrosine nitration as the protein-level consequence of increased RNS formation. Our experiments compared the nickel accumulation and tolerance, the redox signalling and the protein nitration in the agar-grown Arabidopsis thaliana and Brassica juncea exposed to Ni (50 muM nickel chloride). Studying GUS-tagged Arabidopsis lines (ARR5::GUS, ACS8::GUS and DR5::GUS) revealed that Ni-increased lateral root (LR) emergence, and concomitantly reduced LR initiation were accompanied by elevated levels of auxin, cytokinin, and ethylene in the LRs or in upper root parts, whereas Ni-induced primary root shortening is related to decreased auxin, and increased cytokinin and ethylene levels. These suggest the Ni-induced disturbance of hormonal balance in the root system. Results of the comparative study showed that weaker Ni tolerance of A. thaliana was coupled with a Ni-induced increase in RNS, ROS, and hydrogen sulfide levels, as well as with an increase in redox signalling and consequent increment of protein nitration. However, in relative Ni tolerant B. juncea, redox signalling (except for peroxynitrite) was not modified, and Ni-induced intensification of protein tyrosine nitration was less pronounced. Data collectively show that the better Ni tolerance of Brassica juncea may be related to the capability of preventing the induction of redox signalling and consequently to the slighter increase in protein nitration.
PMID: 31784105
Ecotoxicol Environ Saf , IF:4.872 , 2020 Feb , V189 : P109942 doi: 10.1016/j.ecoenv.2019.109942
Selenomethionine induces oxidative stress and modifies growth in rice (Oryza sativa L.) seedlings through effects on hormone biosynthesis and primary metabolism.
Departamento de Biologia Vegetal, Universidade Federal de Vicosa, 36570-900, Vicosa, Minas Gerais, Brazil.; Departamento de Biologia Vegetal, Universidade Federal de Vicosa, 36570-900, Vicosa, Minas Gerais, Brazil. Electronic address: dimas.ribeiro@ufv.br.
Although the chemical characteristics of selenomethionine (SeMet) are similar to those of methionine (Met), the physiological activity of SeMet apparently differs in its ability to stimulate ethylene production in plant tissues. Since selenium alters root architecture of rice seedlings by modifying ethylene production, the investigation of the effect of SeMet and Met on rice growth would be a step forward towards unraveling factors that underlie selenium toxicity. Here, we report that SeMet increased concentrations of reactive oxygen species (ROS), inhibiting auxin and increasing ethylene production in rice seedlings. The effect of SeMet on seedlings was mediated by the inhibition of the abundance of transcripts encoding auxin transport and cell expansion proteins. Moreover, SeMet led to increased seedling respiration, which was positively correlated with organic acids consumption, but negatively with sugars consumption, thereby decreasing seedling growth. In contrast with SeMet treatment, Met did not affect ROS production, hormone biosynthesis and seedling growth, indicating an exclusive selenium effect. The singlet oxygen scavenger, 1,4-diazabicyclooctane, overrode the repressive effect of SeMet in seedling growth. Our results demonstrate a phytotoxic effect of SeMet for rice seedlings and reveal a relationship between reactive oxygen species, hormone homeostasis and carbon availability, which regulates growth responses.
PMID: 31757514
Int J Mol Sci , IF:4.556 , 2020 Feb , V21 (5) doi: 10.3390/ijms21051662
Into the Seed: Auxin Controls Seed Development and Grain Yield.
State Key Laboratory of Agricultural Microbiology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Seed development, which involves mainly the embryo, endosperm and integuments, is regulated by different signaling pathways, leading to various changes in seed size or seed weight. Therefore, uncovering the genetic and molecular mechanisms of seed development has great potential for improving crop yields. The phytohormone auxin is a key regulator required for modulating different cellular processes involved in seed development. Here, we provide a comprehensive review of the role of auxin biosynthesis, transport, signaling, conjugation, and catabolism during seed development. More importantly, we not only summarize the research progress on the genetic and molecular regulation of seed development mediated by auxin but also discuss the potential of manipulating auxin metabolism and its signaling pathway for improving crop seed weight.
PMID: 32121296
Int J Mol Sci , IF:4.556 , 2020 Feb , V21 (4) doi: 10.3390/ijms21041333
Current Perspectives on the Auxin-Mediated Genetic Network that Controls the Induction of Somatic Embryogenesis in Plants.
Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Jagiellonska 28, 40-032 Katowice, Poland.
Auxin contributes to almost every aspect of plant development and metabolism as well as the transport and signalling of auxin-shaped plant growth and morphogenesis in response to endo- and exogenous signals including stress conditions. Consistently with the common belief that auxin is a central trigger of developmental changes in plants, the auxin treatment of explants was reported to be an indispensable inducer of somatic embryogenesis (SE) in a large number of plant species. Treating in vitro-cultured tissue with auxins (primarily 2,4-dichlorophenoxyacetic acid, which is a synthetic auxin-like plant growth regulator) results in the extensive reprogramming of the somatic cell transcriptome, which involves the modulation of numerous SE-associated transcription factor genes (TFs). A number of SE-modulated TFs that control auxin metabolism and signalling have been identified, and conversely, the regulators of the auxin-signalling pathway seem to control the SE-involved TFs. In turn, the different expression of the genes encoding the core components of the auxin-signalling pathway, the AUXIN/INDOLE-3-ACETIC ACIDs (Aux/IAAs) and AUXIN RESPONSE FACTORs (ARFs), was demonstrated to accompany SE induction. Thus, the extensive crosstalk between the hormones, in particular, auxin and the TFs, was revealed to play a central role in the SE-regulatory network. Accordingly, LEAFY COTYLEDON (LEC1 and LEC2), BABY BOOM (BBM), AGAMOUS-LIKE15 (AGL15) and WUSCHEL (WUS) were found to constitute the central part of the complex regulatory network that directs the somatic plant cell towards embryogenic development in response to auxin. The revealing picture shows a high degree of complexity of the regulatory relationships between the TFs of the SE-regulatory network, which involve direct and indirect interactions and regulatory feedback loops. This review examines the recent advances in studies on the auxin-controlled genetic network, which is involved in the mechanism of SE induction and focuses on the complex regulatory relationships between the down- and up-stream targets of the SE-regulatory TFs. In particular, the outcomes from investigations on Arabidopsis, which became a model plant in research on genetic control of SE, are presented.
PMID: 32079138
Int J Mol Sci , IF:4.556 , 2020 Feb , V21 (4) doi: 10.3390/ijms21041323
Overexpression of Grapevine VvIAA18 Gene Enhanced Salt Tolerance in Tobacco.
School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai'an 223003, Jiangsu, China.; Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, Jiangsu, China.
In plants, auxin/indoleacetic acid (Aux/IAA) proteins are transcriptional regulators that regulate developmental process and responses to phytohormones and stress treatments. However, the regulatory functions of the Vitis vinifera L. (grapevine) Aux/IAA transcription factor gene VvIAA18 have not been reported. In this study, the VvIAA18 gene was successfully cloned from grapevine. Subcellular localization analysis in onion epidermal cells indicated that VvIAA18 was localized to the nucleus. Expression analysis in yeast showed that the full length of VvIAA18 exhibited transcriptional activation. Salt tolerance in transgenic tobacco plants and Escherichia. coli was significantly enhanced by VvIAA18 overexpression. Real-time quantitative PCR analysis showed that overexpression of VvIAA18 up-regulated the salt stress-responsive genes, including pyrroline-5-carboxylate synthase (NtP5CS), late embryogenesis abundant protein (NtLEA5), superoxide dismutase (NtSOD), and peroxidase (NtPOD) genes, under salt stress. Enzymatic analyses found that the transgenic plants had higher SOD and POD activities under salt stress. Meanwhile, component analysis showed that the content of proline in transgenic plants increased significantly, while the content of hydrogen peroxide (H2O2) and malondialdehyde (MDA) decreased significantly. Based on the above results, the VvIAA18 gene is related to improving the salt tolerance of transgenic tobacco plants. The VvIAA18 gene has the potential to be applied to enhance plant tolerance to abiotic stress.
PMID: 32075333
Int J Mol Sci , IF:4.556 , 2020 Feb , V21 (4) doi: 10.3390/ijms21041226
Transcriptome Profiling Analysis Reveals Co-regulation of Hormone Pathways in Foxtail Millet during Sclerospora graminicola Infection.
College of Agriculture, Shanxi Agricultural University, Taigu 030801, Shanxi, China.; College of Life Sciences, Shanxi Agricultural University, Taigu 030801, Shanxi, China.
Sclerospora graminicola (Sacc.) Schroeter is a biotrophic pathogen of foxtail millet (Setaria italica) and increasingly impacts crop production. We explored the main factors for symptoms such as dwarfing of diseased plants and the "hedgehog panicle" by determining panicle characteristics of varieties infected with S. graminicola and analyzing the endogenous hormone-related genes in leaves of Jingu 21. Results indicated that different varieties infected by S. graminicola exhibited various symptoms. Transcriptome analysis revealed that the ent-copalyl diphosphate synthetase (CPS) encoded by Seita.2G144900 and ent-kaurene synthase (KS) encoded by Seita.2G144400 were up-regulated 4.7-fold and 2.8-fold, respectively. Results showed that the biosynthesis of gibberellin might be increased, but the gibberellin signal transduction pathway might be blocked. The abscisic acid (ABA) 8'-hydroxylase encoded by Seita.6G181300 was continuously up-regulated by 4.2-fold, 2.7-fold, 14.3-fold, and 12.9-fold from TG1 to TG4 stage, respectively. Seita.2G144900 and Seita.2G144400 increased 79-fold and 51-fold, respectively, at the panicle development stage, promoting the formation of a "hedgehog panicle". Jasmonic acid-related synthesis enzymes LOX2s, AOS, and AOC were up-regulated at the early stage of infection, indicating that jasmonic acid played an essential role in early response to S. graminicola infection. The expression of YUC-related genes of the auxin synthesis was lower than that of the control at TG3 and TG4 stages, but the amidase encoded by Seita.2G313400 was up-regulated by more than 30-fold, indicating that the main biosynthesis pathway of auxin had changed. The results suggest that there was co-regulation of the hormone pathways during the infection of foxtail millet by S. graminicola.
PMID: 32059399
Int J Mol Sci , IF:4.556 , 2020 Feb , V21 (3) doi: 10.3390/ijms21031145
Phyllotaxis Turns Over a New Leaf-A New Hypothesis.
School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.; Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.; Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA.
Phyllotaxis describes the periodic arrangement of plant organs most conspicuously floral. Oscillators generally underlie periodic phenomena. A hypothetical algorithm generates phyllotaxis regulated by the Hechtian growth oscillator of the stem apical meristem (SAM) protoderm. The oscillator integrates biochemical and mechanical force that regulate morphogenetic gradients of three ionic species, auxin, protons and Ca(2+). Hechtian adhesion between cell wall and plasma membrane transduces wall stress that opens Ca(2+) channels and reorients auxin efflux "PIN" proteins; they control the auxin-activated proton pump that dissociates Ca(2+) bound by periplasmic arabinogalactan proteins (AGP-Ca(2+)) hence the source of cytosolic Ca(2+) waves that activate exocytosis of wall precursors, AGPs and PIN proteins essential for morphogenesis. This novel approach identifies the critical determinants of an algorithm that generates phyllotaxis spiral and Fibonaccian symmetry: these determinants in order of their relative contribution are: (1) size of the apical meristem and the AGP-Ca(2+) capacitor; (2) proton pump activity; (3) auxin efflux proteins; (4) Ca(2+) channel activity; (5) Hechtian adhesion that mediates the cell wall stress vector. Arguably, AGPs and the AGP-Ca(2+) capacitor plays a decisive role in phyllotaxis periodicity and its evolutionary origins.
PMID: 32050457
Physiol Plant , IF:4.148 , 2020 Feb , V168 (2) : P473-489 doi: 10.1111/ppl.13050
NO and ROS implications in the organization of root system architecture.
Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, 211004, India.; Amity Institute of Microbial Technology, Amity University Uttar Pradesh, Noida, 201313, India.; Department of Botany, C.M.P. Degree College, A Constitute PG College of University of Allahabad, Allahabad, 211002, India.; Amity Institute of Organic Agriculture, Amity University Uttar Pradesh, Noida, 201313, India.
Over the past decades the role of nitric oxide (NO) and reactive oxygen species (ROS) in signaling and cellular responses to stress has witnessed an exponential trend line. Despite advances in the subject, our knowledge of the role of NO and ROS as regulators of stress and plant growth and their implication in signaling pathways is still partial. The crosstalk between NO and ROS during root formation offers new domains to be explored, as it regulates several plant functions. Previous findings indicate that plants utilize these signaling molecules for regulating physiological responses and development. Depending upon cellular concentration, NO either can stimulate or impede root system architecture (RSA) by modulating enzymes through post-translational modifications. Similarly, the ROS signaling molecule network, in association with other hormonal signaling pathways, control the RSA. The spatial regulation of ROS controls cell growth and ROS determine primary root and act in concert with NO to promote lateral root primordia. NO and ROS are two central messenger molecules which act differentially to upregulate or downregulate the expression of genes pertaining to auxin synthesis and to the configuration of root architecture. The investigation concerning the contribution of donors and inhibitors of NO and ROS can further aid in deciphering their role in root development. With this background, this review provides comprehensive details about the effect and function of NO and ROS in the development of RSA.
PMID: 31747051
Metabolites , IF:4.097 , 2020 Feb , V10 (2) doi: 10.3390/metabo10020068
Metabolite and Phytohormone Profiling Illustrates Metabolic Reprogramming as an Escape Strategy of Deepwater Rice during Partially Submerged Stress.
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.; Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan.; Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata 997-8555, Japan.; Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.; Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 263-8522, Japan.; Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.; Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
Rice varieties that can survive under submergence conditions respond to flooding either by enhancing internode elongation or by quiescence of shoot elongation. Despite extensive efforts to identify key metabolites triggered by complete submergence of rice possessing SUBMERGENCE 1 (SUB1) locus, metabolic responses of internode elongation of deepwater rice governed by the SNORKEL 1 and 2 genes remain elusive. This study investigated specific metabolomic responses under partial submergence (PS) to deepwater- (C9285) and non-deepwater rice cultivars (Taichung 65 (T65)). In addition, we examined the response in a near-isogenic line (NIL-12) that has a C9285 genomic fragment on chromosome 12 introgressed into the genetic background of T65. Under short-term submergence (0-24 h), metabolite profiles of C9285, NIL-12, and T65 were compared to extract significantly changed metabolites in deepwater rice under PS conditions. Comprehensive metabolite and phytohormone profiling revealed increases in metabolite levels in the glycolysis pathway in NIL-12 plants. Under long-term submergence (0-288 h), we found decreased amino acid levels. These metabolomic changes were opposite when compared to those in flood-tolerant rice with SUB1 locus. Auxin conjugate levels related to stress response decreased in NIL-12 lines relative to T65. Our analysis helped clarify the complex metabolic reprogramming in deepwater rice as an escape strategy.
PMID: 32075002
Biomolecules , IF:4.082 , 2020 Feb , V10 (2) doi: 10.3390/biom10020281
Auxin-Abscisic Acid Interactions in Plant Growth and Development.
Department of Biology, Washington University, St. Louis, MO 63130, USA.; Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, MO 63130, USA.; Center for Engineering Mechanobiology, Washington University, St. Louis, MO 63130, USA.
Plant hormones regulate many aspects of plant growth, development, and response to biotic and abiotic stress. Much research has gone into our understanding of individual plant hormones, focusing primarily on their mechanisms of action and the processes that they regulate. However, recent research has begun to focus on a more complex problem; how various plant hormones work together to regulate growth and developmental processes. In this review, we focus on two phytohormones, abscisic acid (ABA) and auxin. We begin with brief overviews of the hormones individually, followed by in depth analyses of interactions between auxin and ABA, focusing on interactions in individual tissues and how these interactions are occurring where possible. Finally, we end with a brief discussion and future prospects for the field.
PMID: 32059519
Biomolecules , IF:4.082 , 2020 Feb , V10 (2) doi: 10.3390/biom10020276
Indoleacetic Acid Levels in Wheat and Rice Seedlings under Oxygen Deficiency and Subsequent Reoxygenation.
Department of Genetics and Biotechnology, Saint-Petersburg State University, Universitetskaya em., 7/9, 199034 Saint-Petersburg, Russia.; Department of Plant Physiology and Biochemistry, Saint-Petersburg State University, Universitetskaya em., 7/9, 199034 Saint-Petersburg, Russia.; Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
The lack of oxygen and post-anoxic reactions cause significant alterations of plant growth and metabolism. Plant hormones are active participants in these alterations. This study focuses on auxin-a phytohormone with a wide spectrum of effects on plant growth and stress tolerance. The indoleacetic acid (IAA) content in plants was measured by ELISA. The obtained data revealed anoxia-induced accumulation of IAA in wheat and rice seedlings related to their tolerance of oxygen deprivation. The highest IAA accumulation was detected in rice roots. Subsequent reoxygenation was accompanied with a fast auxin reduction to the control level. A major difference was reported for shoots: wheat seedlings contained less than one-third of normoxic level of auxin during post-anoxia, while IAA level in rice seedlings rapidly recovered to normoxic level. It is likely that the mechanisms of auxin dynamics resulted from oxygen-induced shift in auxin degradation and transport. Exogenous IAA treatment enhanced plant survival under anoxia by decreased electrolyte leakage, production of hydrogen peroxide and lipid peroxidation. The positive effect of external IAA application coincided with improvement of tolerance to oxygen deprivation in the 35S:iaaM x 35S:iaaH lines of transgene tobacco due to its IAA overproduction.
PMID: 32054127
Plant Cell Physiol , IF:4.062 , 2020 Feb , V61 (2) : P243-254 doi: 10.1093/pcp/pcz228
Time-Series Single-Cell RNA-Seq Data Reveal Auxin Fluctuation during Endocycle.
Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto, 606-8501 Japan.; Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192 Japan.
Appropriate cell cycle regulation is crucial for achieving coordinated development and cell differentiation in multicellular organisms. In Arabidopsis, endoreduplication is often observed in terminally differentiated cells and several reports have shown its molecular mechanisms. Auxin is a key factor for the mode transition from mitotic cell cycle to endocycle; however, it remains unclear if and how auxin maintains the endocycle mode. In this study, we reanalyzed root single-cell transcriptome data and reconstructed cell cycle trajectories of the mitotic cell cycle and endocycle. With progression of the endocycle, genes involved in auxin synthesis, influx and efflux were induced at the specific cell phase, suggesting that auxin concentration fluctuated dynamically. Such induction of auxin-related genes was not observed in the mitotic cell cycle, suggesting that the auxin fluctuation plays some roles in maintaining the endocycle stage. In addition, the expression level of CYCB1;1, which is required for cell division in the M phase, coincided with the expected amount of auxin and cell division. Our analysis also provided a set of genes expressed in specific phases of the cell cycle. Taking these findings together, reconstruction of single-cell transcriptome data enables us to identify properties of the cell cycle more accurately.
PMID: 31841158
Plant Cell Physiol , IF:4.062 , 2020 Feb , V61 (2) : P353-369 doi: 10.1093/pcp/pcz202
Molecular Basis for Natural Vegetative Propagation via Regeneration in North American Lake Cress, Rorippa aquatica (Brassicaceae).
Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-Ku, Kyoto, 603-8555 Japan.; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033 Japan.; Department of Biology, Tokyo Gakugei University, Koganei, Tokyo, 184-8501 Japan.; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045 Japan.; Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, 183-8509 Japan.; Center for Ecological Evolutionary Developmental Biology, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-Ku, Kyoto, 603-8555 Japan.
Some plant species have a striking capacity for regeneration in nature, including regeneration of the entire individual from explants. However, due to the lack of suitable experimental models, the regulatory mechanisms of spontaneous whole plant regeneration are mostly unknown. In this study, we established a novel model system to study these mechanisms using an amphibious plant within Brassicaceae, Rorippa aquatica, which naturally undergoes vegetative propagation via regeneration from leaf fragments. Morphological and anatomical observation showed that both de novo root and shoot organogenesis occurred from the proximal side of the cut edge transversely with leaf vascular tissue. Time-series RNA-seq analysis revealed that auxin and cytokinin responses were activated after leaf amputation and that regeneration-related genes were upregulated mainly on the proximal side of the leaf explants. Accordingly, we found that both auxin and cytokinin accumulated on the proximal side. Application of a polar auxin transport inhibitor retarded root and shoot regeneration, suggesting that the enhancement of auxin responses caused by polar auxin transport enhanced de novo organogenesis at the proximal wound site. Exogenous phytohormone and inhibitor applications further demonstrated that, in R. aquatica, both auxin and gibberellin are required for root regeneration, whereas cytokinin is important for shoot regeneration. Our results provide a molecular basis for vegetative propagation via de novo organogenesis.
PMID: 31651939
Sci Rep , IF:3.998 , 2020 Feb , V10 (1) : P3437 doi: 10.1038/s41598-020-60412-9
Endogenous levels of cytokinins, indole-3-acetic acid and abscisic acid in in vitro grown potato: A contribution to potato hormonomics.
Department of Plant Physiology, Institute for Biological Research "Sinisa Stankovic" - National Institute of Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060, Belgrade, Serbia. martin@ibiss.bg.ac.rs.; Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojova 263, CZ-165 02, Prague 6, Czech Republic.; Department of Plant Physiology, Institute for Biological Research "Sinisa Stankovic" - National Institute of Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060, Belgrade, Serbia.; Laboratory of Mass Spectrometry, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojova 263, CZ-165 02, Prague 6, Czech Republic.; Mining and Metallurgy Institute, Zeleni Bulevar 35, 19219, Bor, Serbia.; Department of Plant Physiology, Faculty of Biology, University of Belgrade, Studentski trg 16, 11000, Belgrade, Serbia.
A number of scientific reports published to date contain data on endogenous levels of various phytohormones in potato (Solanum tuberosum L.) but a complete cytokinin profile of potato tissues, that would include data on all particular molecular forms of cytokinin, has still been missing. In this work, endogenous levels of all analytically detectable isoprenoid cytokinins, as well as the auxin indole-3-acetic acid (IAA), and abscisic acid (ABA) have been determined in shoots and roots of 30 day old in vitro grown potato (cv. Desiree). The results presented here are generally similar to other data reported for in vitro grown potato plants, whereas greenhouse-grown plants typically contain lower levels of ABA, possibly indicating that in vitro grown potato is exposed to chronic stress. Cytokinin N-glucosides, particularly N7-glucosides, are the dominant cytokinin forms in both shoots and roots of potato, whereas nucleobases, as the bioactive forms of cytokinins, comprise a low proportion of cytokinin levels in tissues of potato. Differences in phytohormone composition between shoots and roots of potato suggest specific patterns of transport and/or differences in tissue-specific metabolism of plant hormones. These results represent a contribution to understanding the hormonomics of potato, a crop species of extraordinary economic importance.
PMID: 32103086
Plant Cell Rep , IF:3.825 , 2020 Feb , V39 (2) : P259-271 doi: 10.1007/s00299-019-02489-9
A gain-of-function mutation in Brassinosteroid-insensitive 2 alters Arabidopsis floral organ development by altering auxin levels.
Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, China.; Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, China. zhdawei@scu.edu.cn.; Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, China. hhlin@scu.edu.cn.
KEY MESSAGE: Auxin can alter the fertility of bin2-1 plants and depends on the expression of SHY2. Brassinosteroids (BRs) play important roles in plant growth and developmental processes. By systematically evaluating the phenotypes of BR biosynthesis and BR signaling mutants, researchers have reported that BRs positively regulate floral development. In this study, we found that brassinosteroid-insensitive 2 (bin2-1) and short-hypocotyl 2 (shy2-2) mutants exhibited significantly reduced fertility. These mutants had short inflorescences, decreased floral organ length (short petals, stamens, carpels, and stigmas), and short siliques. Exogenous auxin applications could partially rescue the shortened length of the floral organs and siliques of the bin2-1 mutants. Additional experiments revealed that a lack of SHY2 activity increased the fertility of the bin2-1 mutants. A search for downstream affected genes revealed that auxin influences the expression of ARFs and PINs in the bin2-1 mutants, suggesting that auxin plays a major role in the regulation of bin2-1 plant fertility. Thus, BIN2 plays a role in fertility by affecting auxin levels, mainly by altering the expression of SHY2.
PMID: 31820142
Plant Cell Rep , IF:3.825 , 2020 Feb , V39 (2) : P273-288 doi: 10.1007/s00299-019-02490-2
ZmMYC2 exhibits diverse functions and enhances JA signaling in transgenic Arabidopsis.
Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China.; Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu, 611130, China. qwang@sicau.edu.cn.
KEY MESSAGE: ZmMYC2 was identified as the key regulator of JA signaling in maize and exhibited diverse functions through binding to many gene promoters as well as enhanced JA signaling in transgenic Arabidopsis. The plant hormone jasmonate (JA) extensively coordinates plant growth, development and defensive responses. MYC2 is the master regulator of JA signaling and has been widely studied in many plant species. However, little is known about this transcription factor in maize. Here, we identified one maize transcription factor with amino acid identity of 47% to the well-studied Arabidopsis AtMYC2, named as ZmMYC2. Gene expression analysis demonstrated inducible expression patterns of ZmMYC2 in response to multiple plant hormone treatments, as well as biotic and abiotic stresses. The yeast two-hybrid assay indicated physical interaction among ZmMYC2 and JA signal repressors ZmJAZ14, ZmJAZ17, AtJAZ1 and AtJAZ9. ZmMYC2 overexpression in Arabidopsis myc2myc3myc4 restored the sensitivity to JA treatment, resulting in shorter root growth and inducible anthocyanin accumulation. Furthermore, overexpression of ZmMYC2 in Arabidopsis elevated resistance to Botrytis cinerea. Further ChIP-Seq analysis revealed diverse regulatory roles of ZmMYC2 in maize, especially in the signaling crosstalk between JA and auxin. Hence, we identified ZmMYC2 and characterized its roles in regulating JA-mediated growth, development and defense responses.
PMID: 31741037
Genes (Basel) , IF:3.759 , 2020 Feb , V11 (2) doi: 10.3390/genes11020176
The WUSCHELa (PtoWUSa) is Involved in Developmental Plasticity of Adventitious Root in Poplar.
Experimental Center of Forestry in North China, Chinese Academy of Forestry, Beijing 102300, China.; State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing 100091, China.; Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.; College of Forestry and Biotechnology, Zhejiang Agriculture & Forestry University, Hangzhou 311300, China.
WUSCHEL-RELATED HOMEOBOX (WOX) transcription factors play critical roles in cell fate determination during plant development. As the founding member of the WOX family, WUSCHEL (WUS) is characterized for its role in maintaining stem cell in meristem. In this study, we investigated the function of Populus tomentosa WUSCHELa (PtoWUSa) in adventitious roots (ARs) in poplar. Expression profile analysis showed that PtoWUSa was not only expressed in shoot apical meristem and stem, but also expressed in ARs. Ectopic expression of PtoWUSa in Arabidopsis resulted in shortened primary root, as well as agravitropism and multiple branches. Overexpression of PtoWUSa in poplar increased the number of ARs but decreased their length. Moreover, the AR tip and lateral root tip became larger and swollen. In addition, the expression of auxin transporter genes PIN-FORMED were downregulated in ARs of transgenic plant. Taken together, these results suggest that PtoWUSa could be involved in AR development in poplar through regulating the polar auxin transport in ARs.
PMID: 32041377
Plant Physiol Biochem , IF:3.72 , 2020 Feb , V147 : P141-160 doi: 10.1016/j.plaphy.2019.11.037
Developmental, hormone- and stress-modulated expression profiles of four members of the Arabidopsis copper-amine oxidase gene family.
Department of Sciences, Universita Roma Tre, Roma, 00146, Italy. Electronic address: ilaria.fraudentali@uniroma3.it.; Institute of Plant Sciences, The Volcani Center, ARO, Bet Dagan, 50250, Israel. Electronic address: sandip.ghuge.biotech@gmail.com.; Department of Sciences, Universita Roma Tre, Roma, 00146, Italy. Electronic address: andrea.carucci@outlook.it.; Department of Sciences, Universita Roma Tre, Roma, 00146, Italy; Istituto Nazionale Biostrutture e Biosistemi (INBB), Rome, 00136, Italy. Electronic address: paraskevi.tavladoraki@uniroma3.it.; Department of Sciences, Universita Roma Tre, Roma, 00146, Italy; Istituto Nazionale Biostrutture e Biosistemi (INBB), Rome, 00136, Italy. Electronic address: riccardo.angelini@uniroma3.it.; Department of Life, Health, and Environmental Sciences, Universita dell'Aquila, L'Aquila, 67100, Italy. Electronic address: pousada@univaq.it.; Department of Sciences, Universita Roma Tre, Roma, 00146, Italy; Istituto Nazionale Biostrutture e Biosistemi (INBB), Rome, 00136, Italy. Electronic address: alessandra.cona@uniroma3.it.
Copper-containing amine oxidases (CuAOs) catalyze polyamines (PAs) terminal oxidation producing ammonium, an aminoaldehyde and hydrogen peroxide (H2O2). Plant CuAOs are induced by stress-related hormones, methyl-jasmonate (MeJA), abscisic acid (ABA) and salicylic acid (SA). In the Arabidopsis genome, eight genes encoding CuAOs have been identified. Here, a comprehensive investigation of the expression pattern of four genes encoding AtCuAOs from the alpha and gamma phylogenetic subfamilies, the two peroxisomal AtCuAOalpha2 (At1g31690) and AtCuAOalpha3 (At1g31710) and the two apoplastic AtCuAOgamma1 (At1g62810) and AtCuAOgamma2 (At3g43670), has been carried out by RT-qPCR and promoter::green fluorescent protein-beta-glucuronidase fusion (GFP-GUS). Expression in hydathodes of new emerging leaves (AtCuAOgamma1 and AtCuAOgamma2) and/or cotyledons (AtCuAOalpha2, AtCuAOgamma1 and AtCuAOgamma2) as well as in vascular tissues of new emerging leaves and in cortical root cells at the division/elongation transition zone (AtCuAOgamma1), columella cells (AtCuAOgamma2) or hypocotyl and root (AtCuAOalpha3) was identified. Quantitative and tissue-specific gene expression analysis performed by RT-qPCR and GUS-staining in 5- and 7-day-old seedlings under stress conditions or after treatments with hormones or PAs, revealed that all four AtCuAOs were induced during dehydration recovery, wounding, treatment with indoleacetic acid (IAA) and putrescine (Put). AtCuAOalpha2, AtCuAOalpha3, AtCuAOgamma1 and AtCuAOgamma2 expression in vascular tissues and hydathodes involved in water supply and/or loss, along with a dehydration-recovery dependent gene expression, would suggest a role in water balance homeostasis. Moreover, occurrence in zones where an auxin maximum has been observed along with an IAA-induced alteration of expression profiles, support a role in tissue maturation and xylem differentiation events.
PMID: 31862580
Plant Sci , IF:3.591 , 2020 Feb , V291 : P110358 doi: 10.1016/j.plantsci.2019.110358
Is naphthylphthalamic acid a specific phytotropin? It elevates ethylene and alters metabolic homeostasis in tomato.
Repository of Tomato Genomics Resources, Department of Plant Sciences, University of Hyderabad, Hyderabad, 500046, India.; Repository of Tomato Genomics Resources, Department of Plant Sciences, University of Hyderabad, Hyderabad, 500046, India. Electronic address: rameshwar.sharma@uohyd.ac.in.
In higher plants, phytohormone indole-3-acetic acid is characteristically transported from the apex towards the base of the plant, termed as polar auxin transport (PAT). Among the inhibitors blocking PAT, N-1-naphthylphthalamic acid (NPA) that targets ABCB transporters is most commonly used. NPA-treated light-grown Arabidopsis seedlings show severe inhibition of hypocotyl and root elongation. In light-grown tomato seedlings, NPA inhibited root growth, but contrary to Arabidopsis stimulated hypocotyl elongation. The NPA-stimulation of hypocotyl elongation was milder in blue, red, and far-red light-grown seedlings. The NPA-treatment stimulated emission of ethylene from the seedlings. The scrubbing of ethylene by mercuric perchlorate reduced NPA-stimulated hypocotyl elongation. NPA action on hypocotyl elongation was antagonized by 1-methylcyclopropene, an inhibitor of ethylene action. NPA-treated seedlings had reduced levels of indole-3-butyric acid and higher levels of zeatin in the shoots. NPA did not alter indole-3-acetic levels in shoots. The analysis of metabolic networks indicated that NPA-treatment induced moderate shifts in the networks compared to exogenous ethylene that induced a drastic shift in metabolic networks. Our results indicate that in addition to ethylene, NPA-stimulated hypocotyl elongation in tomato may also involve zeatin and indole-3- butyric acid. Our results indicate that NPA-mediated physiological responses may vary in a species-specific fashion.
PMID: 31928666
BMC Plant Biol , IF:3.497 , 2020 Feb , V20 (1) : P87 doi: 10.1186/s12870-020-2296-7
Identification of microRNAs in developing wheat grain that are potentially involved in regulating grain characteristics and the response to nitrogen levels.
College of Agronomy/National Engineering Research Center for Wheat, Henan Agricultural University, Zhengzhou, 450002, China.; College of Agronomy/National Engineering Research Center for Wheat, Henan Agricultural University, Zhengzhou, 450002, China. xmzxmdy@126.com.; The National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, 450002, China. xmzxmdy@126.com.; College of Agronomy/National Engineering Research Center for Wheat, Henan Agricultural University, Zhengzhou, 450002, China. xmzxwang@163.com.; The National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, 450002, China. xmzxwang@163.com.
BACKGROUND: MicroRNAs (miRNAs) play crucial roles in the regulation of plant development and growth, but little information is available concerning their roles during grain development under different nitrogen (N) application levels. Our objective was to identify miRNAs related to the regulation of grain characteristics and the response to different N fertilizer conditions. RESULTS: A total of 79 miRNAs (46 known and 33 novel miRNAs) were identified that showed significant differential expression during grain development under both high nitrogen (HN) and low nitrogen (LN) treatments. The miRNAs that were significantly upregulated early in grain development target genes involved mainly in cell differentiation, auxin-activated signaling, and transcription, which may be associated with grain size; miRNAs abundant in the middle and later stages target genes mainly involved in carbohydrate and nitrogen metabolism, transport, and kinase activity and may be associated with grain filling. Additionally, we identified 50 miRNAs (22 known and 28 novel miRNAs), of which 11, 9, and 39 were differentially expressed between the HN and LN libraries at 7, 17, and 27 days after anthesis (DAA). The miRNAs that were differentially expressed in response to nitrogen conditions target genes involved mainly in carbohydrate and nitrogen metabolism, the defense response, and transport as well as genes that encode ubiquitin ligase. Only one novel miRNA (PC-5p-2614_215) was significantly upregulated in response to LN treatment at all three stages, and 21 miRNAs showed significant differential expression between HN and LN conditions only at 27 DAA. We therefore propose a model for target gene regulation by miRNAs during grain development with N-responsive patterns. CONCLUSIONS: The potential targets of the identified miRNAs are related to various biological processes, such as carbohydrate/nitrogen metabolism, transcription, cellular differentiation, transport, and defense. Our results indicate that miRNA-mediated networks, via posttranscriptional regulation, play crucial roles in grain development and the N response, which determine wheat grain weight and quality. Our study provides useful information for future research of regulatory mechanisms that focus on improving grain yield and quality.
PMID: 32103721
Plant Mol Biol , IF:3.302 , 2020 Feb , V102 (3) : P287-306 doi: 10.1007/s11103-019-00948-1
RNA-Seq analysis of compatible and incompatible styles of Pyrus species at the beginning of pollination.
College of Horticulture, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang, Qingdao City, 266109, Shandong, China.; College of Horticulture, Qingdao Agricultural University, No. 700 Changcheng Road, Chengyang, Qingdao City, 266109, Shandong, China. haiyongqu@hotmail.com.
KEY MESSAGE: At the early stage of pollination, the difference in gene expression between compatibility and incompatibility is highly significant about the pollen-specific expression of the LRR gene, resistance, and defensin genes. In Rosaceae, incompatible pollen can penetrate into the style during the gametophytic self-incompatibility response. It is therefore considered a stylar event rather than a stigmatic event. In this study, we explored the differences in gene expression between compatibility and incompatibility in the early stage of pollination. The self-compatible pear variety "Jinzhuili" is a naturally occurring bud mutant from "Yali", a leading Chinese native cultivar exhibiting typical gametophytic self-incompatibility. We collected the styles of 'Yali' and 'Jinzhuili' at 0.5 and 2 h after self-pollination and then performed high-throughput sequencing. According to the KEGG analysis of the differentially expressed genes, several metabolic pathways, such as "Plant hormone signal transduction", "Plant-pathogen interaction", are the main pathways was the most represented pathway. Quantitative PCR was used to validate these differential genes. The expression levels of genes related to pollen growth and disease inhibition, such as LRR (Leucine-rich repeat extensin), resistance, defensin, and auxin, differed significantly between compatible and incompatible pollination. Interestingly, at 0.5 h, most of these genes were upregulated in the compatible pollination system compared with the incompatible pollination system. Calcium transport, which requires ATPase, also demonstrated upregulated expression. In summary, the self-incompatibility reaction was initiated when the pollen land on the stigma.
PMID: 31872308
Molecules , IF:3.267 , 2020 Feb , V25 (3) doi: 10.3390/molecules25030664
Biostimulant Potential of Scenedesmus obliquus Grown in Brewery Wastewater.
Department of Chemical Engineering, University of Almeria, Canada San Urbano, s/n, 04120 Almeria, Spain.; LNEG, National Laboratory of Energy and Geology I.P., Bioenergy Unit, Estrada do Paco do Lumiar 22, 1649-038 Lisbon, Portugal.
Microalgae are microorganisms with the capacity to contribute to the sustainable and healthy food production, in addition to wastewater treatment. The subject of this work was to determine the potential of Scenedesmus obliquus microalga grown in brewery wastewater to act as a plant biostimulant. The germination index of watercress seeds, as well as the auxin-like activity in mung bean and cucumber, and in the cytokinin-like activity in cucumber bioassays were used to evaluate the biostimulant potential. Several biomass processes were studied, such as centrifugation, ultrasonication and enzymatic hydrolysis, as well as the final concentration of microalgal extracts to determine their influence in the biostimulant activity of the Scenedesmus biomass. The results showed an increase of 40% on the germination index when using the biomass at 0.1 g/L, without any pre-treatment. For auxin-like activity, the best results (up to 60% with respect to control) were obtained at 0.5 g/L of biomass extract, after a combination of cell disruption, enzymatic hydrolysis and centrifugation. For cytokinin-like activity, the best results (up to 187.5% with respect to control) were achieved without cell disruption, after enzymatic hydrolysis and centrifugation at a biomass extract concentration of 2 g/L.
PMID: 32033149
J Plant Physiol , IF:3.013 , 2020 Feb , V245 : P153082 doi: 10.1016/j.jplph.2019.153082
Biosynthesis pathway of indole-3-acetyl-myo-inositol during development of maize (Zea mays L.) seeds.
Nicolaus Copernicus University in Torun, Department of Biochemistry, Lwowska 1 St, 87-100 Torun, Poland. Electronic address: maciejost@umk.pl.; Nicolaus Copernicus University in Torun, Department of Biochemistry, Lwowska 1 St, 87-100 Torun, Poland.; Nicolaus Copernicus University in Torun, Department of Plant Physiology and Biotechnology, Lwowska 1 St, 87-100 Torun, Poland.
Indole-3-acetic acid (IAA) conjugation is one of the mechanisms responsible for auxin homeostasis. IAA ester conjugates biosynthesis has been studied during development of maize seeds where IAA-inositol (IAInos) and its glycosidic forms make up about 50 % of its ester conjugates pool. 1-O-indole-3-acetyl-beta-d-glucose (IAGlc) synthase and indole-3-acetyl transferase (IAInos synthase) are key enzymes in a two-step pathway of IAInos synthesis. In the first reaction, IAA is glucosylated to a high energy acetal, 1-O-indole-3-acetyl-beta-d-glucose by IAGlc synthase, whereas in the second step, IAInos synthase transfers IAA moiety to myo-inositol forming a stable auxin ester, indole-3-acetyl-myo-inositol (IAInos). It should be mentioned that IAGlc synthase catalyzes a reversible reaction with unfavourable equilibrium that delivers IAGlc for favourable transacylation to IAInos. This is the first study where IAGlc synthase and IAInos synthase are simultaneously analyzed by enzymatic activity assay and quantitative RT-PCR in maize seeds at four stages of development (13, 26, 39 and 52 Days After Flowering). Activity of IAGlc/IAInos synthases as well as their expression profiles during seed development were different. While both enzymatic activities and ZmIAIn expression were the highest in seeds at 26 DAF, the highest expression of ZmIAGlc was observed at 13 DAF. Protein gel blot analysis showed that IAInos synthase exists as a mixture of several isoforms at a similar protein level at particular stages of seed development. Neither of other ester conjugates of IAA (IAA-mannose) nor IAA-amino acids were detected at the stages studied. Catalytic activity of l-tryptophan aminotransferase involved in IAA biosynthesis as well as UDPG pyrophosphorylase, synthesizing UDPG as a substrate for IAGlc synthase, were also analyzed. l-tryptophan aminotransferase activity was the highest at 26 DAF. Changes in enzyme activity of UDPG pyrophosphorylase are difficult to interpret. Expression levels of ZmIPS and ZmIPP encoding two enzymes of myo-inositol biosynthesis pathway: inositol-x-phosphate synthase (IPS) and inositol-x-phosphate phosphatase (IPP), respectively, were analyzed. 26 DAF seeds displayed the highest expression level of ZmIPS, whereas transcription of ZmIPP was the highest at 13 DAF.
PMID: 31862648
Plants (Basel) , IF:2.762 , 2020 Feb , V9 (2) doi: 10.3390/plants9020272
AUXIN RESPONSE FACTOR 1 Acts as a Positive Regulator in the Response of Poplar to Trichoderma asperellum Inoculation in Overexpressing Plants.
College of Landscape Architecture, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China.; Photosynthesis Research Center, CAS Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.; College of Life Sciences, Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
Numerous Trichoderma strains have been reported to be optimal biofertilizers and biocontrol agents with low production costs and environmentally friendly properties. Trichoderma spp. promote the growth and immunity of plants by multiple means. Interfering with the hormonal homeostasis in plants is the most critical strategy. However, the mechanisms underlying plants' responses to Trichoderma remain to be further elucidated. Auxin is the most important phytohormone that regulates almost every aspect of a plant's life, especially the trade-off between growth and defense. The AUXIN RESPONSE FACTOR (ARF) family proteins are key players in auxin signaling. We studied the responses and functions of the PdPapARF1 gene in a hybrid poplar during its interaction with beneficial T. asperellum strains using transformed poplar plants with PdPapARF1 overexpression (on transcription level in this study). We report that PdPapARF1 is a positive regulator for promoting poplar growth and defense responses, as does T. asperellum inoculation. PdPapARF1 also turned out to be a positive stimulator of adventitious root formation. Particularly, the overexpression of PdPapARF1 induced a 32.3% increase in the height of 40-day-old poplar plants and a 258% increase in the amount of adventitious root of 3-week-old subcultured plant clones. Overexpressed PdPapARF1 exerted its beneficial functions through modulating the hormone levels of indole acetic acid (IAA), jasmonic acid (JA), and salicylic acid (SA) in plants and activating their signaling pathways, creating similar results as inoculated with T. asperellum. Particularly, in the overexpressing poplar plants, the IAA level increased by approximately twice of the wild-type plants; and the signaling pathways of IAA, JA, and SA were drastically activated than the wild-type plants under pathogen attacks. Our report presents the potential of ARFs as the crucial and positive responders in plants to Trichoderma inducing.
PMID: 32092896
Plants (Basel) , IF:2.762 , 2020 Feb , V9 (2) doi: 10.3390/plants9020240
Genome-Wide Analysis of Gene Expression Provides New Insights into Waterlogging Responses in Barley (Hordeum vulgare L.).
Brandon Research and Development Centre, Agriculture and Agri-Food Canada, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada.; Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada.
Waterlogging is a major abiotic stress causing oxygen depletion and carbon dioxide accumulation in the rhizosphere. Barley is more susceptible to waterlogging stress than other cereals. To gain a better understanding, the genome-wide gene expression responses in roots of waterlogged barley seedlings of Yerong and Deder2 were analyzed by RNA-Sequencing. A total of 6736, 5482, and 4538 differentially expressed genes (DEGs) were identified in waterlogged roots of Yerong at 72 h and Deder2 at 72 and 120 h, respectively, compared with the non-waterlogged control. Gene Ontology (GO) enrichment analyses showed that the most significant changes in GO terms, resulted from these DEGs observed under waterlogging stress, were related to primary and secondary metabolism, regulation, and oxygen carrier activity. In addition, more than 297 transcription factors, including members of MYB, AP2/EREBP, NAC, WRKY, bHLH, bZIP, and G2-like families, were identified as waterlogging responsive. Tentative important contributors to waterlogging tolerance in Deder2 might be the highest up-regulated DEGs: Trichome birefringence, alpha/beta-Hydrolases, Xylanase inhibitor, MATE efflux, serine carboxypeptidase, and SAUR-like auxin-responsive protein. The study provides insights into the molecular mechanisms underlying the response to waterlogging in barley, which will be of benefit for future studies of molecular responses to waterlogging and will greatly assist barley genetic research and breeding.
PMID: 32069892
Plants (Basel) , IF:2.762 , 2020 Feb , V9 (2) doi: 10.3390/plants9020221
Genome-Wide Identification and Expression Analysis of Auxin Response Factor (ARF) Gene Family in Longan (Dimocarpus longan L.).
College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China.; Institute of Genetics and Breeding in Horticultural Plants, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Auxin response factor (ARF) is the key regulator involved in plant development. Despite their physiological importance identified in various woody plants, the functions of ARF genes in longan were still not clear. In this study, 17 longan ARF genes (DlARF) were identified using the reference longan genome data. According to the phylogenetic relationships among longan, Arabidopsis and apple, DlARFs were divided into four classes. Most DlARFs showed a closer relationship with ARFs from apple than those from Arabidopsis. The analysis of gene structure and domain revealed high similarity of different ARF genes in the same class. Typical features of B3-type DNA binding domain (DBD) motif, Auxin Resp motifs, and a highly conserved C-terminal Phox and Bem1 (PB1) domain were present in all DlARFs except for DlARF-2,-3,-13 which lacked PBI domain. Expression profiles of 17 DlARF genes in longan different tissues showed that some DlARF genes were tissues-specific genes. Analysis of three longan transcriptomes showed seven DlARFs (DlARF-1,-2,-6,-8,-9,-11,-16) had higher expression levels during floral bud differentiation of common longan and in the buds of 'Sijimi', suggesting these genes may promote floral bud differentiation in longan. Further qPCR analysis showed that among seven DlARF genes, the expression levels of DlARF-2,-6,-11,-16 increased significantly during the physiological differentiation stage of longan floral buds, confirming that they may play a role in flowering induction. Promoter sequence analysis revealed cis-elements related to flowering induction such as low-temperature responsiveness motif and circadian control motif. Motifs linked with hormone response for instance Auxin, MeJA, Gibberellin, and Abscisic acid were also found in promoters. This study provides a comprehensive overview of the ARF gene family in longan. Our findings could provide new insights into the complexity of the regulation of ARFs at the transcription level that may be useful to develop breeding strategies to improve development or promote flowering in longan.
PMID: 32046357
Plants (Basel) , IF:2.762 , 2020 Feb , V9 (2) doi: 10.3390/plants9020185
Expression Profile of PIN-Formed Auxin Efflux Carrier Genes during IBA-Induced In Vitro Adventitious Rooting in Olea europaea L.
MED - Mediterranean Institute for Agriculture, Environment and Development, Instituto de Investigacao e Formacao Avancada, Universidade de Evora, Polo da Mitra, Ap. 94, 7006-554 Evora, Portugal.; Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA.; MED - Mediterranean Institute for Agriculture, Environment and Development & Departamento de Fitotecnia, Escola de Ciencias e Tecnologia, Universidade de Evora, Polo da Mitra, Ap. 94, 7006-554 Evora, Portugal.
Exogenous auxins supplementation plays a central role in the formation of adventitious roots (AR) for several plant species. However, the molecular mechanisms underlying the process of adventitious rooting are still not completely understood and many plants with economic value, including several olive cultivars, exhibit a recalcitrant behavior towards cutting propagation, which limits its availability in plant nurseries. PIN-formed proteins are auxin efflux transporters that have been widely characterized in several plant species due to their involvement in many developmental processes including root formation. The present study profiled the expression of the OePIN1a-c, OePIN2b, OePIN3a-c, OePIN5a-c, OePIN6, and OePIN8 gene members during indole-3-butyric acid (IBA)-induced in vitro adventitious rooting using the olive cultivar 'Galega vulgar'. Gene expression analysis by quantitative real time PCR (RT-qPCR) showed drastic downregulation of most transcripts, just a few hours after explant inoculation, in both nontreated and IBA-treated microcuttings, albeit gene downregulation was less pronounced in IBA-treated stems. In contrast, OePIN2b showed a distinct expression pattern being upregulated in both conditions, and OePIN5b was highly upregulated in IBA-induced stems. All transcripts, except OePIN8, showed different expression profiles between nontreated and IBA-treated explants throughout the rooting experiment. Additionally, high levels of reactive oxygen species (ROS) were observed soon after explant preparation, decreasing a few hours after inoculation. Altogether, the results suggest that wounding-related ROS production, associated with explant preparation for rooting, may have an impact on auxin transport and distribution via changes in OePIN gene expression. Moreover, the application of exogenous auxin may modulate auxin homeostasis through regulation of those genes, leading to auxin redistribution throughout the stem-base tissue, which may ultimately play an important role in AR formation.
PMID: 32028698
Plants (Basel) , IF:2.762 , 2020 Feb , V9 (2) doi: 10.3390/plants9020184
Natural Variation in Adventitious Rooting in the Alpine Perennial Arabis alpina.
Institute for Plant Sciences, University of Cologne, Zulpicher Str. 47B, 50674 Cologne, Germany.; Max Planck Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Cologne, Germany.; Cluster of Excellence on Plant Sciences "From Complex Traits towards Synthetic Modules", 40225 Dusseldorf, Germany.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90736 Umea, Sweden.
Arctic alpine species follow a mixed clonal-sexual reproductive strategy based on the environmental conditions at flowering. Here, we explored the natural variation for adventitious root formation among genotypes of the alpine perennial Arabis alpina that show differences in flowering habit. We scored the presence of adventitious roots on the hypocotyl, main stem and axillary branches on plants growing in a long-day greenhouse. We also assessed natural variation for adventitious rooting in response to foliar auxin spray. In both experimental approaches, we did not detect a correlation between adventitious rooting and flowering habit. In the greenhouse, and without the application of synthetic auxin, the accession Wca showed higher propensity to produce adventitious roots on the main stem compared to the other accessions. The transcript accumulation of the A. alpina homologue of the auxin inducible GH3.3 gene (AaGH3.3) on stems correlated with the adventitious rooting phenotype of Wca. Synthetic auxin, 1-Naphthaleneacetic acid (1-NAA), enhanced the number of plants with adventitious roots on the main stem and axillary branches. A. alpina plants showed an age-, dosage- and genotype-dependent response to 1-NAA. Among the genotypes tested, the accession Dor was insensitive to auxin and Wca responded to auxin on axillary branches.
PMID: 32028613
Int Microbiol , IF:1.833 , 2020 Feb doi: 10.1007/s10123-020-00122-4
Effects of Trichoderma asperellum and its siderophores on endogenous auxin in Arabidopsis thaliana under iron-deficiency stress.
College of Life Science, Shandong Normal University, Jinan, 250014, China. zhaolei@sdu.edu.cn.; College of Life Science, Shandong Normal University, Jinan, 250014, China.
Iron (Fe) deficiency is one of the major limiting factors affecting crop yields. Trichoderma asperellum Q1, a biocontrol and plant growth promoting fungus, can produce the siderophore which has a high affinity to Fe(3+) in the absence of iron. In this study, Trichoderma asperellum Q1 was found to be able to promote growth of Arabidopsis thaliana in an iron-deficient or insoluble iron-containing (Fe2O3) medium. It also can produce more siderophore and indole-3-acetic acid (IAA) as the concentration of iron ions decreased. However, it is unclear that the relationship between siderophore and IAA in promoting plant growth. Both Trichoderma asperellum Q1 and siderophore promotes not only the DR5::GFP transgenic Arabidopsis thaliana seedlings, in which the root IAA is labeled by green fluorescent protein gene, but also increases the content of endogenous IAA in the roots, which was shown by the fluorescence study. The strongest fluorescence was observed in the treated group inoculated with Trichoderma asperellum Q1 under the condition of insoluble iron. In the case of iron-free medium, adding siderophore also increased the observed fluorescence intensity. These results suggest that the siderophores produced by Trichoderma asperellum Q1 increased the content of IAA in Arabidopsis roots by enhancing the conversion of poorly soluble iron or by the siderophore itself.
PMID: 32080772
Plant Direct , IF:1.725 , 2020 Feb , V4 (2) : Pe00205 doi: 10.1002/pld3.205
Subfunctionalization of phytochrome B1/B2 leads to differential auxin and photosynthetic responses.
Department of Biology University of Puget Sound Tacoma Washington.
Gene duplication and polyploidization are genetic mechanisms that instantly add genetic material to an organism's genome. Subsequent modification of the duplicated material leads to the evolution of neofunctionalization (new genetic functions), subfunctionalization (differential retention of genetic functions), redundancy, or a decay of duplicated genes to pseudogenes. Phytochromes are light receptors that play a large role in plant development. They are encoded by a small gene family that in tomato is comprised of five members: PHYA, PHYB1, PHYB2, PHYE, and PHYF. The most recent gene duplication within this family was in the ancestral PHYB gene. Using transcriptome profiling, co-expression network analysis, and physiological and molecular experimentation, we show that tomato SlPHYB1 and SlPHYB2 exhibit both common and non-redundant functions. Specifically, PHYB1 appears to be the major integrator of light and auxin responses, such as gravitropism and phototropism, while PHYB1 and PHYB2 regulate aspects of photosynthesis antagonistically to each other, suggesting that the genes have subfunctionalized since their duplication.
PMID: 32128473
Plant Pathol J , IF:1.57 , 2020 Feb , V36 (1) : P1-10 doi: 10.5423/PPJ.RW.12.2019.0295
Salicylic Acid as a Safe Plant Protector and Growth Regulator.
Department of Plant Medicals, Andong National University, Andong 36729, Korea.
Since salicylic acid (SA) was discovered as an elicitor of tobacco plants inducing the resistance against Tobacco mosaic virus (TMV) in 1979, increasing reports suggest that SA indeed is a key plant hormone regulating plant immunity. In addition, recent studies indicate that SA can regulate many different responses, such as tolerance to abiotic stress, plant growth and development, and soil microbiome. In this review, we focused on the recent findings on SA's effects on resistance to biotic stresses in different plant-pathogen systems, tolerance to different abiotic stresses in different plants, plant growth and development, and soil microbiome. This allows us to discuss about the safe and practical use of SA as a plant defense activator and growth regulator. Crosstalk of SA with different plant hormones, such as abscisic acid, ethylene, jasmonic acid, and auxin in different stress and developmental conditions were also discussed.
PMID: 32089657
J Vis Exp , IF:1.163 , 2020 Feb (156) doi: 10.3791/60782
Agrobacterium-Mediated Immature Embryo Transformation of Recalcitrant Maize Inbred Lines Using Morphogenic Genes.
Department of Agronomy, Iowa State University; Department of Applied Science and Technology, Corteva Agriscience.; Department of Agronomy, Iowa State University; Crop Bioengineering Center, Iowa State University; Interdepartmental Plant Biology Major, Iowa State University.; Department of Agronomy, Iowa State University; Crop Bioengineering Center, Iowa State University.; Department of Agronomy, Iowa State University; Crop Bioengineering Center, Iowa State University; Interdepartmental Genetics and Genomics Major, Iowa State University.; Department of Applied Science and Technology, Corteva Agriscience.; Department of Agronomy, Iowa State University; Crop Bioengineering Center, Iowa State University; kanwang@iastate.edu.
Demonstrated here is a detailed protocol for Agrobacterium-mediated genetic transformation of maize inbred lines using morphogenic genes Baby boom (Bbm) and Wuschel2 (Wus2). Bbm is regulated by the maize phospholipid transferase gene (Pltp) promoter, and Wus2 is under the control of a maize auxin-inducible (Axig1) promoter. An Agrobacterium strain carrying these morphogenic genes on transfer DNA (T-DNA) and extra copies of Agrobacterium virulence (vir) genes are used to infect maize immature embryo explants. Somatic embryos form on the scutella of infected embryos and can be selected by herbicide resistance and germinated into plants. A heat-activated cre/loxP recombination system built into the DNA construct allows for removal of morphogenic genes from the maize genome during an early stage of the transformation process. Transformation frequencies of approximately 14%, 4%, and 4% (numbers of independent transgenic events per 100 infected embryos) can be achieved for W22, B73, and Mo17, respectively, using this protocol.
PMID: 32116304