Nat Plants , IF:15.793 , 2021 Jul doi: 10.1038/s41477-021-00969-z
AFB1 controls rapid auxin signalling through membrane depolarization in Arabidopsis thaliana root.
Department of Experimental Plant Biology, Charles University, Prague, Czech Republic.; Department of Chemical Engineering, University of Chemistry and Technology, Prague, Czech Republic.; Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, Australia.; New Technologies-Research Centre, University of West Bohemia, Plzen, Czech Republic.; International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China.; Department of Experimental Plant Biology, Charles University, Prague, Czech Republic. matyas.fendrych@natur.cuni.cz.
The membrane potential reflects the difference between cytoplasmic and apoplastic electrical potentials and is essential for cellular operation. The application of the phytohormone auxin (3-indoleacetic acid (IAA)) causes instantaneous membrane depolarization in various cell types(1-6), making depolarization a hallmark of IAA-induced rapid responses. In root hairs, depolarization requires functional IAA transport and TIR1-AFB signalling(5), but its physiological importance is not understood. Specifically in roots, auxin triggers rapid growth inhibition(7-9) (RGI), a process required for gravitropic bending. RGI is initiated by the TIR1-AFB co-receptors, with the AFB1 paralogue playing a crucial role(10,11). The nature of the underlying rapid signalling is unknown, as well as the molecular machinery executing it. Even though the growth and depolarization responses to auxin show remarkable similarities, the importance of membrane depolarization for root growth inhibition and gravitropism is unclear. Here, by combining the DISBAC2(3) voltage sensor with microfluidics and vertical-stage microscopy, we show that rapid auxin-induced membrane depolarization tightly correlates with RGI. Rapid depolarization and RGI require the AFB1 auxin co-receptor. Finally, AFB1 is essential for the rapid formation of the membrane depolarization gradient across the gravistimulated root. These results clarify the role of AFB1 as the central receptor for rapid auxin responses.
PMID: 34282287
Nat Commun , IF:14.919 , 2021 Jul , V12 (1) : P4321 doi: 10.1038/s41467-021-24550-6
Coordination of biradial-to-radial symmetry and tissue polarity by HD-ZIP II proteins.
Institute of Molecular Biology and Pathology, National Research Council, Rome, Italy.; Research Centre for Genomics and Bioinformatics, Council for Agricultural Research and Economics (CREA), Rome, Italy.; Department of Crop Genetics, John Innes Centre, Norwich, UK. lars.ostergaard@jic.ac.uk.; Department of Crop Genetics, John Innes Centre, Norwich, UK. laila.moubayidin@jic.ac.uk.
Symmetry establishment is a critical process in the development of multicellular organs and requires careful coordination of polarity axes while cells actively divide within tissues. Formation of the apical style in the Arabidopsis gynoecium involves a bilateral-to-radial symmetry transition, a stepwise process underpinned by the dynamic distribution of the plant morphogen auxin. Here we show that SPATULA (SPT) and the HECATE (HEC) bHLH proteins mediate the final step in the style radialisation process and synergistically control the expression of adaxial-identity genes, HOMEOBOX ARABIDOPSIS THALIANA 3 (HAT3) and ARABIDOPSIS THALIANA HOMEOBOX 4 (ATHB4). HAT3/ATHB4 module drives radialisation of the apical style by promoting basal-to-apical auxin flow and via a negative feedback mechanism that finetune auxin distribution through repression of SPT expression and cytokinin sensitivity. Thus, this work reveals the molecular basis of axes-coordination and hormonal cross-talk during the sequential steps of symmetry transition in the Arabidopsis style.
PMID: 34262040
Nat Commun , IF:14.919 , 2021 Jul , V12 (1) : P4267 doi: 10.1038/s41467-021-24548-0
Sphingolipids mediate polar sorting of PIN2 through phosphoinositide consumption at the trans-Golgi network.
Laboratoire de Biogenese Membranaire, Univ. Bordeaux, Villenave d'Ornon, France.; BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX, USA.; Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon1, CNRS, INRAE, Lyon, France.; Plant Molecular and Cellular Biology Laboratory and Integrative Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA.; Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany.; Platforme Proteome, Univ. Bordeaux, Bordeaux, France.; MetaboHub-Bordeaux Metabolome INRAE, Villenave d'Ornon, France.; Bordeaux Imaging Centre, Plant Imaging Platform, UMS 3420 University of Bordeaux-CNRS, INRAE, Villenave-d'Ornon Cedex, France.; Laboratoire de Biogenese Membranaire, Univ. Bordeaux, Villenave d'Ornon, France. yohann.boutte@u-bordeaux.fr.
The lipid composition of organelles acts as a landmark to define membrane identity and specify subcellular function. Phosphoinositides are anionic lipids acting in protein sorting and trafficking at the trans-Golgi network (TGN). In animal cells, sphingolipids control the turnover of phosphoinositides through lipid exchange mechanisms at endoplasmic reticulum/TGN contact sites. In this study, we discover a mechanism for how sphingolipids mediate phosphoinositide homeostasis at the TGN in plant cells. Using multiple approaches, we show that a reduction of the acyl-chain length of sphingolipids results in an increased level of phosphatidylinositol-4-phosphate (PtdIns(4)P or PI4P) at the TGN but not of other lipids usually coupled to PI4P during exchange mechanisms. We show that sphingolipids mediate Phospholipase C (PLC)-driven consumption of PI4P at the TGN rather than local PI4P synthesis and that this mechanism is involved in the polar sorting of the auxin efflux carrier PIN2 at the TGN. Together, our data identify a mode of action of sphingolipids in lipid interplay at the TGN during protein sorting.
PMID: 34257291
Mol Plant , IF:13.164 , 2021 Jul doi: 10.1016/j.molp.2021.07.001
The INO80 chromatin remodeling complex promotes thermo-morphogenesis by connecting H2A.Z eviction and active transcription in Arabidopsis.
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.; State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.; State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China. Electronic address: dhjiang@genetics.ac.cn.
Global warming imposes a major threat to plant growth and crop production. In some plants including Arabidopsis thaliana, elevated temperatures induce a series of morphological and developmental adjustments, termed thermomorphogenesis to facilitate plant cooling under high-temperature conditions. Plant thermal response is suppressed by histone variant H2A.Z. At warm temperatures, H2A.Z is evicted from nucleosomes at thermo-responsive genes, resulting in their expression changes. However, the mechanisms that regulate H2A.Z eviction and subsequent transcription changes are largely unknown. Here, we show that the INO80 chromatin remodeling complex (INO80-C) promotes thermomorphogenesis and activates the expression of thermo-responsive and auxin-related genes. INO80-C associates with PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), a potent regulator in thermomorphogenesis, and mediates temperature-induced H2A.Z eviction at PIF4 targets. Moreover, INO80-C directly interacts with COMPASS-like and transcription elongation factors to promote active histone modification Histone H3 lysine 4 trimethylation (H3K4me3) and RNA Polymerase II (RNA Pol II) elongation, leading to the thermal induction of transcription. Notably, transcription elongation factors SPT4 and SPT5 are required for the H2A.Z eviction at PIF4 targets, suggesting the cooperation of INO80-C and transcription elongation in H2A.Z removal. Our results demonstrate that the (PIF4)-(INO80-C)-(COMPASS-like)-(transcription elongator) module controls plant thermal response, and establish a link between H2A.Z eviction and active transcription.
PMID: 34242850
Mol Plant , IF:13.164 , 2021 Jul , V14 (7) : P1185-1198 doi: 10.1016/j.molp.2021.05.005
The miR166-SlHB15A regulatory module controls ovule development and parthenocarpic fruit set under adverse temperatures in tomato.
Institute of Plant Sciences Paris-Saclay, INRAE, CNRS, Universite Paris-Saclay, Orsay 91405, France.; Institut Jean-Pierre Bourgin, INRAE, Versailles, France.; HM Clause, Mas Saint-Pierre, Quartier La Galine, Saint-Remy de Provence 13210, France.; Hazera Seeds Ltd, Berurim M.P., Shikmim 7983700, Israel.; Institute of Plant Sciences Paris-Saclay, INRAE, CNRS, Universite Paris-Saclay, Orsay 91405, France. Electronic address: abdelhafid.bendahmane@inrae.fr.
Fruit set is inhibited by adverse temperatures, with consequences on yield. We isolated a tomato mutant producing fruits under non-permissive hot temperatures and identified the causal gene as SlHB15A, belonging to class III homeodomain leucine-zipper transcription factors. SlHB15A loss-of-function mutants display aberrant ovule development that mimics transcriptional changes occurring in fertilized ovules and leads to parthenocarpic fruit set under optimal and non-permissive temperatures, in field and greenhouse conditions. Under cold growing conditions, SlHB15A is subjected to conditional haploinsufficiency and recessive dosage sensitivity controlled by microRNA 166 (miR166). Knockdown of SlHB15A alleles by miR166 leads to a continuum of aberrant ovules correlating with parthenocarpic fruit set. Consistent with this, plants harboring an Slhb15a-miRNA166-resistant allele developed normal ovules and were unable to set parthenocarpic fruit under cold conditions. DNA affinity purification sequencing and RNA-sequencing analyses revealed that SlHB15A is a bifunctional transcription factor expressed in the ovule integument. SlHB15A binds to the promoters of auxin-related genes to repress auxin signaling and to the promoters of ethylene-related genes to activate their expression. A survey of tomato genetic biodiversity identified pat and pat-1, two historical parthenocarpic mutants, as alleles of SlHB15A. Taken together, our findings demonstrate the role of SlHB15A as a sentinel to prevent fruit set in the absence of fertilization and provide a mean to enhance fruiting under extreme temperatures.
PMID: 33964458
Plant Cell , IF:11.277 , 2021 Jul doi: 10.1093/plcell/koab175
AUXIN RESPONSE FACTOR 6 and 7 control the flag leaf angle in rice by regulating secondary cell wall biosynthesis of lamina joints.
Joint International Research Laboratory of Metabolic & Developmental Sciences, State Key Laboratory of Hybrid Rice, SJTU-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.; School of Biosciences, University of Melbourne, Parkville VIC 3010, Melbourne, Australia.; Department of Plant & Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark.; School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia.; Future Food Beacon and School of Biosciences, University of Nottingham, LE12 5RD, UK.; Copenhagen Plant Science Center, University of Copenhagen, 1871, Frederiksberg C, Denmark.
Flag leaf angle impacts the photosynthetic capacity of densely grown plants and is thus an important agronomic breeding trait for crop architecture and yield. The hormone auxin plays a key role in regulating this trait, yet the underlying molecular and cellular mechanisms remain unclear. Here, we report that two rice (Oryza sativa) auxin response factors (ARFs), OsARF6 and OsARF17, which are highly expressed in lamina joint tissues, control flag leaf angle in response to auxin. Loss-of-function double osarf6 osarf17 mutants displayed reduced secondary cell wall levels of lamina joint sclerenchymatous cells (Sc), resulting in an exaggerated flag leaf angle and decreased grain yield under dense planting conditions. Mechanical measurements indicated that the mutant lamina joint tissues were too weak to support the weight of the flag leaf blade, resembling the phenotype of the rice increased leaf angle1 (ila1) mutant. We demonstrate that OsARF6 and OsARF17 directly bind to the ILA1 promoter independently and synergistically to activate its expression. In addition, auxin-induced ILA1 expression was dependent on OsARF6 and OsARF17. Collectively, our study reveals a mechanism that integrates auxin signaling with secondary cell wall composition to determine flag leaf angle, providing breeding targets in rice, and potentially other cereals, for this key trait.
PMID: 34245297
Plant Cell , IF:11.277 , 2021 Jul doi: 10.1093/plcell/koab183
GmPIN-dependent polar auxin transport is involved in soybean nodule development.
College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.; Haixia Institute of Science and Technology, Horticultural Plant Biology and Metabolomics Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.; College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.; Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.; University of Chinese Academy of Sciences, Beijing 100049, China.; State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.; State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.; Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria.; Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic.
To overcome nitrogen deficiency, legume roots establish symbiotic interactions with nitrogen-fixing rhizobia that is fostered in specialized organs (nodules). Similar to other organs, nodule formation is determined by a local maximum of the phytohormone auxin at the primordium site. However, how auxin regulates nodule development remains poorly understood. Here, we found that in soybean, (Glycine max), dynamic auxin transport driven by PIN-FORMED (PIN) transporter GmPIN1 is involved in nodule primordium formation. GmPIN1 was specifically expressed in nodule primordium cells and GmPIN1 was polarly localized in these cells. Two nodulation regulators, (iso)flavonoids trigger expanded distribution of GmPIN1b to root cortical cells, and cytokinin rearranges GmPIN1b polarity. Gmpin1abc triple mutants generated with CRISPR-Cas9 showed impaired establishment of auxin maxima in nodule meristems and aberrant divisions in the nodule primordium cells. Moreover, overexpression of GmPIN1 suppressed nodule primordium initiation. GmPIN9d, an ortholog of Arabidopsis thaliana PIN2, acts together with GmPIN1 later in nodule development to acropetally transport auxin in vascular bundles, fine-tuning the auxin supply for nodule enlargement. Our findings reveal how PIN-dependent auxin transport modulates different aspects of soybean nodule development and suggest that establishment of auxin gradient is a prerequisite for the proper interaction between legumes and rhizobia.
PMID: 34240197
Plant Cell , IF:11.277 , 2021 Jul , V33 (6) : P1945-1960 doi: 10.1093/plcell/koab076
Mapping and engineering of auxin-induced plasma membrane dissociation in BRX family proteins.
Department of Plant Molecular Biology, University of Lausanne, Biophore Building, Lausanne 1015, Switzerland.; Plant Systems Biology, Technical University of Munich, Freising 85354, Germany.
Angiosperms have evolved the phloem for the long-distance transport of metabolites. The complex process of phloem development involves genes that only occur in vascular plant lineages. For example, in Arabidopsis thaliana, the BREVIS RADIX (BRX) gene is required for continuous root protophloem differentiation, together with PROTEIN KINASE ASSOCIATED WITH BRX (PAX). BRX and its BRX-LIKE (BRXL) homologs are composed of four highly conserved domains including the signature tandem BRX domains that are separated by variable spacers. Nevertheless, BRX family proteins have functionally diverged. For instance, BRXL2 can only partially replace BRX in the root protophloem. This divergence is reflected in physiologically relevant differences in protein behavior, such as auxin-induced plasma membrane dissociation of BRX, which is not observed for BRXL2. Here we dissected the differential functions of BRX family proteins using a set of amino acid substitutions and domain swaps. Our data suggest that the plasma membrane-associated tandem BRX domains are both necessary and sufficient to convey the biological outputs of BRX function and therefore constitute an important regulatory entity. Moreover, PAX target phosphosites in the linker between the two BRX domains mediate the auxin-induced plasma membrane dissociation. Engineering these sites into BRXL2 renders this modified protein auxin-responsive and thereby increases its biological activity in the root protophloem context.
PMID: 33751121
Plant Cell , IF:11.277 , 2021 Jul , V33 (6) : P1907-1926 doi: 10.1093/plcell/koab084
The Arabidopsis MATERNAL EFFECT EMBRYO ARREST45 protein modulates maternal auxin biosynthesis and controls seed size by inducing AINTEGUMENTA.
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.; Novogene Bioinformatics Institute, Beijing, 100020, China.
Seed size is a major factor determining crop yields that is controlled through the coordinated development of maternal and zygotic tissues. Here, we identified Arabidopsis MATERNAL EFFECT EMBRYO ARREST45 (MEE45) as a B3 transcription factor that controls cell proliferation and maternally regulates seed size through its transcriptional activation of AINTEGUMENTA (ANT) and its downstream control of auxin biosynthesis in the ovule integument. After characterizing reduced seed and organ size phenotypes in mee45 mutants and finding that overexpression of MEE45 causes oversized seeds, we discovered that the MEE45 protein can bind to the promoter region of the ANT locus and positively regulate its transcription. ANT in-turn activates the expression of auxin biosynthetic genes (e.g. YUCCA4) in the ovule integument. Our results thus illustrate mechanisms underlying maternal tissue-mediated regulation of seed size and suggest that MEE45 and its downstream components can be harnessed to develop higher-yielding crop varieties.
PMID: 33730150
Plant Cell , IF:11.277 , 2021 Jul , V33 (6) : P1927-1944 doi: 10.1093/plcell/koab080
The microtubule-associated protein WDL4 modulates auxin distribution to promote apical hook opening in Arabidopsis.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
The unique apical hook in dicotyledonous plants protects the shoot apical meristem and cotyledons when seedlings emerge through the soil. Its formation involves differential cell growth under the coordinated control of plant hormones, especially ethylene and auxin. Microtubules are essential players in plant cell growth that are regulated by multiple microtubule-associated proteins (MAPs). However, the role and underlying mechanisms of MAP-microtubule modules in differential cell growth are poorly understood. In this study, we found that the previously uncharacterized Arabidopsis MAP WAVE-DAMPENED2-LIKE4 (WDL4) protein plays a positive role in apical hook opening. WDL4 exhibits a temporal expression pattern during hook development in dark-grown seedlings that is directly regulated by ethylene signaling. WDL4 mutants showed a delayed hook opening phenotype while overexpression of WDL4 resulted in enhanced hook opening. In particular, wdl4-1 mutants exhibited stronger auxin accumulation in the concave side of the apical hook. Furthermore, the regulation of the auxin maxima and trafficking of the auxin efflux carriers PIN-FORMED1 (PIN1) and PIN7 in the hook region is critical for WDL4-mediated hook opening. Together, our study demonstrates that WDL4 positively regulates apical hook opening by modulating auxin distribution, thus unraveling a mechanism for MAP-mediated differential plant cell growth.
PMID: 33730147
Proc Natl Acad Sci U S A , IF:11.205 , 2021 Jul , V118 (29) doi: 10.1073/pnas.2018799118
OsPDCD5 negatively regulates plant architecture and grain yield in rice.
State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Fudan University, Shanghai 200438, China.; Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai 440400, China.; Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, Beijing 100101, China.; State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha 410125, China.; Ministry of Education Key Laboratory of Crop Physiology, Ecology and Genetic Breeding College of Agronomy, Jiangxi Agricultural University, Nanchang 330045, China.; Institute of Crop Breeding and Cultivation, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China.; State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha 410125, China; brzhao652@hhrrc.ac.cn jsyang@fudan.edu.cn luoxj@fudan.edu.cn.; State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Fudan University, Shanghai 200438, China; brzhao652@hhrrc.ac.cn jsyang@fudan.edu.cn luoxj@fudan.edu.cn.
Plant architecture is an important agronomic trait that affects crop yield. Here, we report that a gene involved in programmed cell death, OsPDCD5, negatively regulates plant architecture and grain yield in rice. We used the CRISPR/Cas9 system to introduce loss-of-function mutations into OsPDCD5 in 11 rice cultivars. Targeted mutagenesis of OsPDCD5 enhanced grain yield and improved plant architecture by increasing plant height and optimizing panicle type and grain shape. Transcriptome analysis showed that OsPDCD5 knockout affected auxin biosynthesis, as well as the gibberellin and cytokinin biosynthesis and signaling pathways. OsPDCD5 interacted directly with OsAGAP, and OsAGAP positively regulated plant architecture and grain yield in rice. Collectively, these findings demonstrate that OsPDCD5 is a promising candidate gene for breeding super rice cultivars with increased yield potential and superior quality.
PMID: 34266944
Curr Biol , IF:10.834 , 2021 Jul doi: 10.1016/j.cub.2021.06.055
Periodic root branching is influenced by light through an HY1-HY5-auxin pathway.
College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, 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.; Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, 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; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River and State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River and State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, 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.; Laboratory of Medicinal Plant, Institute of Basic Medical Sciences, School of Basic Medicine, Biomedical Research Institute, Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, China.; School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China.; College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: wbshenh@njau.edu.cn.; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River and State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: wexua@njau.edu.cn.
The spacing of lateral roots (LRs) along the main root in plants is driven by an oscillatory signal, often referred to as the "root clock" that represents a pre-patterning mechanism that can be influenced by environmental signals. Light is an important environmental factor that has been previously reported to be capable of modulating the root clock, although the effect of light signaling on the LR pre-patterning has not yet been fully investigated. In this study, we reveal that light can activate the transcription of a photomorphogenic gene HY1 to maintain high frequency and amplitude of the oscillation signal, leading to the repetitive formation of pre-branch sites. By grafting and tissue-specific complementation experiments, we demonstrated that HY1 generated in the shoot or locally in xylem pole pericycle cells was sufficient to regulate LR branching. We further found that HY1 can induce the expression of HY5 and its homolog HYH, and act as a signalosome to modulate the intracellular localization and expression of auxin transporters, in turn promoting auxin accumulation in the oscillation zone to stimulate LR branching. These fundamental mechanistic insights improve our understanding of the molecular basis of light-controlled LR formation and provide a genetic interconnection between shoot- and root-derived signals in regulating periodic LR branching.
PMID: 34283998
J Hazard Mater , IF:10.588 , 2021 Jul , V413 : P125402 doi: 10.1016/j.jhazmat.2021.125402
Diclofenac modified the root system architecture of Arabidopsis via interfering with the hormonal activities of auxin.
SELS Center, Division of Biotechnology, College of Bioresources and Environmental Science, Chonbuk National University, Iksan 54596, Republic of Korea.; SELS Center, Division of Biotechnology, College of Bioresources and Environmental Science, Chonbuk National University, Iksan 54596, Republic of Korea. Electronic address: activase@jbnu.ac.kr.
Diclofenac, a pharmaceutical and personal care product, is accumulating in various environmental matrices worldwide. Increased irrigation has facilitated an influx of environmental diclofenac into agricultural products, which potentially threatens non-target living organisms. In this study, we demonstrated that diclofenac modified the growth and root developmental processes of plants by disturbing the activity of auxin, a group of major phytohormones. Exogenous diclofenac treatment retarded growth and induced oxidative stress in young seedlings of Arabidopsis thaliana. In the developmental perspective, diclofenac altered the root system architecture, which was also similarly observed under exogenous IAA (a natural form of phytoalexins) treatment. The effects of diclofenac on the root development of A. thaliana were mediated through canonical auxin signaling pathways. However, when diclofenac and IAA were treated in combination, diclofenac suppressed the activity of IAA in root system architecture. At the molecular level, diclofenac significantly inhibited the activity of IAA upregulating the expression of early auxin-responsive marker genes. In conclusion, diclofenac modified the root development of A. thaliana via interfering with the activities of natural auxin. These results indicate that diclofenac could potentially act as an environmental contaminant disturbing the natural developmental processes of plants.
PMID: 33626476
New Phytol , IF:10.151 , 2021 Jul doi: 10.1111/nph.17633
Broadening the roles of UDP-glycosyltransferases in auxin homeostasis and plant development.
Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umea, Sweden.; John Innes Centre, NR4 7UA, Norwich, United Kingdom.
The levels of the important plant growth regulator indole-3-acetic acid (IAA) are tightly controlled within plant tissues to spatiotemporally orchestrate concentration gradients that drive plant growth and development. Metabolic inactivation of bioactive IAA is known to participate in the modulation of IAA maxima and minima. IAA can be irreversibly inactivated by oxidation and conjugation to Aspartate and Glutamate. Usually overlooked because its reversible nature, the most abundant inactive IAA form is the IAA-glucose (IAA-glc) conjugate. Glycosylation of IAA in Arabidopsis thaliana is reported to be carried out by the UDP-glycosyltransferase 84B1 (UGT84B1), while UGT74D1 has been implicated in the glycosylation of the irreversibly formed IAA catabolite oxIAA. Here we demonstrate that both UGT84B1 and UGT74D1 modulate IAA levels throughout plant development by dual IAA and oxIAA glycosylation. Moreover, we identify a novel UGT subfamily whose members redundantly mediate the glycosylation of oxIAA and modulate skotomorphogenic growth.
PMID: 34289137
New Phytol , IF:10.151 , 2021 Jul doi: 10.1111/nph.17617
PIN-mediated polar auxin transport regulations in plant tropic responses.
Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.; Research Center for Plant Functional Genes and Tissue Culture Technology, College of Bioscience and Bioengineering, Jiangxi Agricultural University, 330045, Nanchang, China.; Department of Biotechnology, Taif University, P.O.BOX 11099, Taif, 21944, Kingdom of Saudi Arabia.
Tropisms, growth responses to environmental stimuli such as light or gravity, are spectacular examples of adaptive plant development. The plant hormone auxin serves as a major coordinative signal. The PIN auxin exporters, through their dynamic polar subcellular localizations, redirect auxin fluxes in response to environmental stimuli and the resulting auxin gradients across organs underly differential cell elongation and bending. In this review, we discuss recent advances concerning regulations of PIN polarity during tropisms, focusing on PIN phosphorylation and trafficking. We also cover how environmental cues regulate PIN actions during tropisms, and a crucial role of auxin feedback on PIN polarity during bending termination. Finally, the interactions between different tropisms are reviewed to understand plant adaptive growth in the natural environment.
PMID: 34254313
Cold Spring Harb Perspect Biol , IF:10.005 , 2021 Jul doi: 10.1101/cshperspect.a039933
Auxin in Root Development.
Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.
Root system architecture is an important determinant of below-ground resource capture and hence overall plant fitness. The plant hormone auxin plays a central role in almost every facet of root development from the cellular to the whole-root-system level. Here, using Arabidopsis as a model, we review the multiple gene signaling networks regulated by auxin biosynthesis, conjugation, and transport that underpin primary and lateral root development. We describe the role of auxin in establishing the root apical meristem and discuss how the tight spatiotemporal regulation of auxin distribution controls transitions between cell division, cell growth, and differentiation. This includes the localized reestablishment of mitotic activity required to elaborate the root system via the production of lateral roots. We also summarize recent discoveries on the effects of auxin and auxin signaling and transport on the control of lateral root gravitropic setpoint angle (GSA), a critical determinant of the overall shape of the root system. Finally, we discuss how environmental conditions influence root developmental plasticity by modulation of auxin biosynthesis, transport, and the canonical auxin signaling pathway.
PMID: 34312248
J Exp Bot , IF:6.992 , 2021 Jul doi: 10.1093/jxb/erab357
Wheat SHORT ROOT LENGTH 1 gene TaSRL1 regulates root length in an auxin-dependent pathway.
College of Agronomy, Henan Agricultural University, Zhengzhou 450000, China.; National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Root is the unique organ of water and nutrients uptake and sensing environmental stimulus in the soil. The optimization of root system architecture contributes to the stress tolerance and yield improvement. ERF (ETHYLENE RESPONSIVE FACTOR) is one of plant specific transcription factor families associated with various developmental processes and stress tolerance. We cloned a novel ERF transcription factor gene TaSRL1 (SHORT ROOT LENGTH 1) from wheat (Triticum aestivum) which is mainly expressed in root. Ectopic expression of TaSRL1 in rice exhibited short root length and plant height. TaSRL1 regulated expression of genes related to auxin synthesis, transport and signaling. Further studies revealed that TaSRL1 induced expression of the auxin transport gene TaPIN2 by directly binding to its promoter, while the interaction of TaSRL1 and TaTIFY9 repressed TaPIN2 expression. Sequence polymorphisms and association analysis showed that TaSRL1-4A was associated with root depth and angle, plant height and 1000-grain weight of wheat. The haplotype Hap-4A-2 with shallow roots, short plant height and high 1000-grain weight has been positively selected in the Chinese wheat breeding process. Therefore, we demonstrated that TaSRL1 functions as a direct regulator of TaPIN2 in the auxin-dependent pathway, and integrates auxin and JA signaling by interacting with TaTIFY9 to repress root growth. Furthermore, the molecular marker of TaSRL1-4A is valuable for the improvement of root system, plant architecture and yield in wheat breeding process.
PMID: 34328188
J Exp Bot , IF:6.992 , 2021 Jul doi: 10.1093/jxb/erab319
The Quiescent Center and Root Regeneration.
The Institute of Plant Sciences, Faculty of Agriculture, The Hebrew University, Israel.
Since its discovery by F.A.L Clowes, extensive research has been dedicated to identifying the functions of the quiescent center (QC). One of the earliest hypotheses was that it serves a key role in regeneration of the root meristem. Recent works provide support for this hypothesis and began to elucidate the molecular mechanisms underlying this phenomenon. There are two scenarios to consider when assessing the role of the QC in regeneration. One, when the damage leaves the QC intact, and the other, when the QC itself is destroyed. In the first scenario, multiple factors are recruited to activate QC cell division in order to replace damaged cells, but whether the QC has a role in the second scenario is less clear. Using both gene expression studies and following cell division pattern has shown that the QC is assembled gradually, only to appear as a coherent identity late in regeneration. Similar late emergence of the QC was observed during the de novo formation of the lateral root meristem. These observations can lead to the conclusion that the QC has no role in regeneration. However, activities normally occurring in QC cells, such as local auxin biosynthesis, are still found during regeneration but occur in different cells in the regenerating meristem. Thus, we explore an alternative hypothesis, that following destruction of the QC, QC-related gene activity is temporarily distributed to other cells in the regenerating meristem, only coalesce into a distinct cell identity when regeneration is complete.
PMID: 34324634
J Exp Bot , IF:6.992 , 2021 Jul doi: 10.1093/jxb/erab351
The transcription factor PagLBD3 contributes to the regulation of secondary growth in Populus.
College of Forestry, State Forestry and Grassland Administration Key Laboratory of Silviculture in downstream areas of the Yellow River, Shandong Agriculture University, Taian, Shandong 271018, China.; College of Life Science, State Key Laboratory of Crop Biology, Shandong Agriculture University, Taian, Shandong 271018, China.; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China.
LATERAL ORGAN BOUNDARIES DOMAIN (LBD) genes encode plant-specific transcription factors that participate in regulating various developmental processes. In this study, we genetically characterized PagLBD3 as an important regulator of secondary growth in Populus. Overexpression of PagLBD3 increased stem secondary growth in Populus with significantly higher rate of cambial cells differentiated into phloem, while dominant repression of PagLBD3 significantly decreased the rate of cambial cells differentiated into phloem. Furthermore, we identified 1756 PagLBD3 genome-wide putative direct target genes (DTGs) through RNA sequencing (RNA-seq) coupled DNA affinity purification followed by sequencing (DAP-seq) assays. Gene Ontology analysis revealed that genes regulated by PagLBD3 were enriched in biological pathways regulating meristem development, xylem development, and auxin transport. Several central regulator genes for vascular development, including PHLOEM INTERCALATED WITH XYLEM (PXY), WUSCHEL RELATED HOMEOBOX4 (WOX4), Secondary Wall-Associated NAC Domain 1s (SND1-B2) and Vascular-Related NAC-Domain 6s (VND6-B1), were identified as PagLBD3 DTGs. Together, our results suggested that PagLBD3 and its DTGs form a complex transcriptional network to modulate cambium activity and phloem/xylem differentiation.
PMID: 34313722
J Exp Bot , IF:6.992 , 2021 Jul , V72 (15) : P5390-5406 doi: 10.1093/jxb/erab224
A C-terminal encoded peptide, ZmCEP1, is essential for kernel development in maize.
State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis and Utilization (MOE), Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193, China.; National Maize Improvement Center of China, China Agricultural University, Beijing, 100193, China.
C-terminal encoded peptides (CEPs) are peptide hormones which act as mobile signals coordinating important developmental programs. Previous studies have unraveled that CEPs are able to regulate plant growth and abiotic stress via cell-to-cell communication in Arabidopsis and rice; however, little is known about their roles in maize. Here, we examined the spatiotemporal expression pattern of ZmCEP1 and showed that ZmCEP1 is highly expressed in young ears and tassels of maize, particularly in the vascular bundles of ears. Heterologous expression of ZmCEP1 in Arabidopsis results in smaller plants and seed size. Similarly, overexpression of ZmCEP1 in maize decreased the plant and ear height, ear length, kernel size, and 100-kernel weight. Consistently, exogenous application of the synthesized ZmCEP1 peptide to the roots of Arabidopsis and maize inhibited root elongation. Knock-out of ZmCEP1 through CRISPR/Cas9 significantly increased plant and ear height, kernel size and 100-kernel weight. Transcriptome analysis revealed that knock-out of ZmCEP1 up-regulated a subset of genes involved in nitrogen metabolism, nitrate transport, sugar transport and auxin response. Thus, these results provide new insights into the genetic and molecular function of ZmCEP1 in regulating kernel development and plant growth, providing novel opportunities for maize breeding.
PMID: 34104938
J Exp Bot , IF:6.992 , 2021 Jul , V72 (15) : P5599-5611 doi: 10.1093/jxb/erab196
Melatonin promotes Arabidopsis primary root growth in an IAA-dependent manner.
Key Laboratory of Horticultural Plant Biology Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.; Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute, The Chinese Academy of Agricultural Sciences, Wuhan, Hubei, 430071, China.; College of Life Sciences, Northwest A& F University, Yangling Shaanxi, 712100, China.
Melatonin has been characterized as a growth regulator in plants. Melatonin shares tryptophan as the precursor with the auxin indole-3-acetic acid (IAA), but the interplay between melatonin and IAA remains controversial. In this study, we aimed to dissect the relationship between melatonin and IAA in regulating Arabidopsis primary root growth. We observed that melatonin concentrations ranging from 10-9 to 10-6 M functioned as IAA mimics to promote primary root growth in Arabidopsis wild type, as well as in pin-formed (pin) single and double mutants. Transcriptome analysis showed that changes in gene expression after melatonin and IAA treatment were moderately correlated. Most of the IAA-regulated genes were co-regulated by melatonin, indicating that melatonin and IAA regulated a similar subset of genes. Melatonin partially rescued primary root growth defects in pin single and double mutant plants. However, melatonin treatment had little effect on primary root growth in the presence of high concentrations of auxin biosynthesis inhibitors, or polar transport inhibitor, and could not rescue the root length defect of the IAA biosynthesis quintuple mutant yucQ. Therefore, we propose that melatonin promotes primary root growth in an IAA-dependent manner.
PMID: 34009365
Development , IF:6.868 , 2021 Jul , V148 (14) doi: 10.1242/dev.197210
Arabidopsis vascular complexity and connectivity controls PIN-FORMED1 dynamics and lateral vein patterning during embryogenesis.
Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA.; Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA.; BPMP, University of Montpellier, CNRS, INRAE, Institut Agro, Montpellier 34060, France.
Arabidopsis VASCULATURE COMPLEXITY AND CONNECTIVITY (VCC) is a plant-specific transmembrane protein that controls the development of veins in cotyledons. Here, we show that the expression and localization of the auxin efflux carrier PIN-FORMED1 (PIN1) is altered in vcc developing cotyledons and that overexpression of PIN1-GFP partially rescues vascular defects of vcc in a dosage-dependent manner. Genetic analyses suggest that VCC and PINOID (PID), a kinase that regulates PIN1 polarity, are both required for PIN1-mediated control of vasculature development. VCC expression is upregulated by auxin, likely as part of a positive feedback loop for the progression of vascular development. VCC and PIN1 localized to the plasma membrane in pre-procambial cells but were actively redirected to vacuoles in procambial cells for degradation. In the vcc mutant, PIN1 failed to properly polarize in pre-procambial cells during the formation of basal strands, and instead, it was prematurely degraded in vacuoles. VCC plays a role in the localization and stability of PIN1, which is crucial for the transition of pre-procambial cells into procambial cells that are involved in the formation of basal lateral strands in embryonic cotyledons.
PMID: 34308982
Development , IF:6.868 , 2021 Jul , V148 (14) doi: 10.1242/dev.197210
Arabidopsis vascular complexity and connectivity controls PIN-FORMED1 dynamics and lateral vein patterning during embryogenesis.
Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA.; Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA.; BPMP, University of Montpellier, CNRS, INRAE, Institut Agro, Montpellier 34060, France.
Arabidopsis VASCULATURE COMPLEXITY AND CONNECTIVITY (VCC) is a plant-specific transmembrane protein that controls the development of veins in cotyledons. Here, we show that the expression and localization of the auxin efflux carrier PIN-FORMED1 (PIN1) is altered in vcc developing cotyledons and that overexpression of PIN1-GFP partially rescues vascular defects of vcc in a dosage-dependent manner. Genetic analyses suggest that VCC and PINOID (PID), a kinase that regulates PIN1 polarity, are both required for PIN1-mediated control of vasculature development. VCC expression is upregulated by auxin, likely as part of a positive feedback loop for the progression of vascular development. VCC and PIN1 localized to the plasma membrane in pre-procambial cells but were actively redirected to vacuoles in procambial cells for degradation. In the vcc mutant, PIN1 failed to properly polarize in pre-procambial cells during the formation of basal strands, and instead, it was prematurely degraded in vacuoles. VCC plays a role in the localization and stability of PIN1, which is crucial for the transition of pre-procambial cells into procambial cells that are involved in the formation of basal lateral strands in embryonic cotyledons.
PMID: 34137447
Plant J , IF:6.417 , 2021 Jul doi: 10.1111/tpj.15424
Local regulation of auxin transport in root-apex transition zone mediates aluminium-induced Arabidopsis root growth inhibition.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Science, Shandong University (Qingdao), Qingdao, 266237, P. R. China.; School of Life Science, Qingdao Agricultural University, Qingdao, 266109, P. R. China.; Department of Biochemistry, Okayama University of Science, Okayama, 700-0005, Japan.; Department of Plant Systems Biology, VIB, Technologiepark 927, B-9052, Ghent, Belgium.; Department of Plant Biotechnology and Genetics, Ghent University, Technologiepark 927, B-9052, Ghent, Belgium.; Mendel Centre for Genomics and Proteomics of Plants Systems, Masaryk University, Brno, 004205, Czech Republic.
Aluminium (Al) stress is a major limiting factor for worldwide crop production in acid soils. In Arabidopsis thaliana, the TAA1-dependent local auxin biosynthesis in the root-apex transition zone (TZ), the the major perception site for Al toxicity, is crucial for the Al-induced root growth inhibition, while the mechanism underlying Al-regulated auxin accumulation in the TZ is not fully understood. In this study, the role of auxin transport in Al-induced local auxin accumulation in the TZ and root growth inhibition was investigated. Our results showed that PIN-FORMED (PIN) proteins such as PIN1, PIN3, PIN4 and PIN7, and AUX1/LAX proteins such as AUX1, LAX1 and LAX2 were all ectopically up-regulated in the root-apex TZ in response to Al stress, and co-ordinately regulate the local auxin accumulation in the TZ and root growth inhibition. The ectopic up-regulation of PIN1 in the TZ under Al stress was regulated by both ethylene and auxin, with auxin signalling acting downstream of ethylene. Al-induced PIN1 up-regulation and auxin accumulation in the root-apex TZ was also regulated by the calossin-like protein BIG. Together, these studies provide insight about how Al stress induces local auxin accumulation in the TZ and root-growth inhibition through the local regulation of auxin transport.
PMID: 34273207
Plant J , IF:6.417 , 2021 Jul doi: 10.1111/tpj.15415
Integration of the SMXL/D53 strigolactone signalling repressors in the model of shoot branching regulation in Pisum sativum.
The University of Queensland, ARC Centre for Plant Success in Nature and Agriculture and School of Biological Sciences, St Lucia, QLD, 4072, Australia.; Centre for Agriculture and the Bioeconomy, Institute for Future Environments, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD, 4000, Australia.; National Key Facility for Crop Gene Resources and Genetic Improvement, ICS, CAAS, Beijing, 100081, China.; Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Universite Paris-Saclay, 78000, Versailles, France.; Universite Paris-Sud, Universite Paris-Saclay, 91405, Orsay, France.; Agroecologie, AgroSup Dijon, INRAE, Univ. Bourgogne, Univ. Bourgogne Franche-Comte, F-21000, Dijon, France.
DWARF53 (D53) in rice (Oryza sativa) and its homologs in Arabidopsis (Arabidopsis thaliana), SUPPRESSOR OF MAX2-LIKE 6 (SMXL6), SMXL7 and SMXL8, are well established negative regulators of strigolactone signalling involved in shoot branching. Little is known of pea (Pisum sativum) homologs and whether D53 and related SMXLs are specific to strigolactone signalling pathways. Here, we identify two allelic pea mutants, dormant3 (dor3), and demonstrate through gene mapping and sequencing that DOR3 corresponds to a homolog of D53 and SMXL6/SMXL7, designated PsSMXL7. Phenotype analysis, gene expression, protein and hormone quantification assays were performed to determine the role of PsSMXL7 in bud outgrowth regulation and the role of PsSMXL7 and D53 in integrating strigolactone and cytokinin responses. Like D53 and related SMXLs, we show that PsSMXL7 is strigolactone degradable, and induces feedback upregulation of PsSMXL7 transcript. Here we reveal a system conserved in pea and rice, whereby CK also upregulates PsSMXL7/D53 transcripts, providing a clear mechanism for strigolactone and cytokinin cross-talk in the regulation of branching. Further deepening our understanding of the branching network in pea, we provide evidence that strigolactone acts via PsSMXL7 to modulate auxin content via PsAFB5, which itself regulates expression of strigolactone biosynthesis genes. We therefore show that PsSMXL7 is key to a triple hormone network involving an auxin-SL feedback mechanism and SL-CK crosstalk.
PMID: 34245626
Plant J , IF:6.417 , 2021 Jul doi: 10.1111/tpj.15406
An HD-ZIP transcription factor, MxHB13, integrates auxin-regulated and juvenility-determined control of adventitious rooting in Malus xiaojinensis.
College of Horticulture, China Agricultural University, Beijing, China.
Adventitious root (AR) formation is a critical factor in the vegetative propagation of forestry and horticultural plants. Competence for AR formation declines in many species during the miR156/SPL-mediated vegetative phase change. Auxin also plays a regulatory role in AR formation. In apple rootstock, both high miR156 expression and exogenous auxin application are prerequisites for AR formation. However, the mechanism by which the miR156/SPL module interacts with auxin in controlling AR formation is unclear. In this paper, leafy cuttings of juvenile (Mx-J) and adult (Mx-A) phase Malus xiaojinensis were used in an RNA-sequencing experiment. The results revealed that numerous genes involved in phytohormone signaling, carbohydrate metabolism, cell dedifferentiation, and reactivation were downregulated in Mx-A cuttings in response to indole butyric acid treatment. Among the differentially expressed genes, an HD-ZIP transcription factor gene, MxHB13, was found to be under negative regulation of MdSPL26 by directly binding to MxHB13 promoter. MxTIFY9 interacts with MxSPL26 and may play a role in co-repressing the expression of MxHB13. The expression of MxTIFY9 was induced by exogenous indole butyric acid. MxHB13 binds to the promoter of MxABCB19-2 and positively affects the expression. A model is proposed in which MxHB13 links juvenility-limited and auxin-limited AR recalcitrance mechanisms in Mx-A.
PMID: 34218490
Int J Mol Sci , IF:5.923 , 2021 Jul , V22 (14) doi: 10.3390/ijms22147749
Actin Isovariant ACT7 Modulates Root Thermomorphogenesis by Altering Intracellular Auxin Homeostasis.
United Graduate School of Agricultural Sciences, Iwate University, Morioka 020-8550, Japan.; Department of Plant Bio Sciences, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.; Agri-Innovation Center, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.
High temperature stress is one of the most threatening abiotic stresses for plants limiting the crop productivity world-wide. Altered developmental responses of plants to moderate-high temperature has been shown to be linked to the intracellular auxin homeostasis regulated by both auxin biosynthesis and transport. Trafficking of the auxin carrier proteins plays a major role in maintaining the cellular auxin homeostasis. The intracellular trafficking largely relies on the cytoskeletal component, actin, which provides track for vesicle movement. Different classes of actin and the isovariants function in regulating various stages of plant development. Although high temperature alters the intracellular trafficking, the role of actin in this process remains obscure. Using isovariant specific vegetative class actin mutants, here we demonstrate that ACTIN 7 (ACT7) isovariant plays an important role in regulating the moderate-high temperature response in Arabidopsis root. Loss of ACT7, but not ACT8 resulted in increased inhibition of root elongation under prolonged moderate-high temperature. Consistently, kinematic analysis revealed a drastic reduction in cell production rate and cell elongation in act7-4 mutant under high temperature. Quantification of actin dynamicity reveals that prolonged moderate-high temperature modulates bundling along with orientation and parallelness of filamentous actin in act7-4 mutant. The hypersensitive response of act7-4 mutant was found to be linked to the altered intracellular auxin distribution, resulted from the reduced abundance of PIN-FORMED PIN1 and PIN2 efflux carriers. Collectively, these results suggest that vegetative class actin isovariant, ACT7 modulates the long-term moderate-high temperature response in Arabidopsis root.
PMID: 34299366
Int J Mol Sci , IF:5.923 , 2021 Jul , V22 (14) doi: 10.3390/ijms22147396
Genome-Wide Identification and Characterization of PIN-FORMED (PIN) Gene Family Reveals Role in Developmental and Various Stress Conditions in Triticum aestivum L.
Department of Life Science, College of Life Science and Biotechnology, Dongguk University, Goyang 10326, Korea.; Krishi Vigyan Kendra, Swami Keshwanand Rajasthan Agricultural University, Bikaner 334603, India.; Faculty of Agriculture, Sri Sri University, Cuttack 754006, India.; Department of Biotechnology, Centurion University of Technology and Management Jatni, Bhubaneswar 754006, India.; Department of Biological Engineering, College of Engineering, Konkuk University, Seoul 143701, Korea.; Department of Biological and Environmental Science, Dongguk University, Goyang 10326, Korea.; Research Institute of Biotechnology and Medical Converged Science, Dongguk University, Goyang 10326, Korea.; Department of Bioindustry and Bioresource Engineering, Plant Engineering Research Institute, Sejong University, Seoul 05006, Korea.; Department of Dairy Microbiology, College of Dairy Science and Food Technology, Raipur 49200, India.
PIN-FORMED (PIN) genes play a crucial role in regulating polar auxin distribution in diverse developmental processes, including tropic responses, embryogenesis, tissue differentiation, and organogenesis. However, the role of PIN-mediated auxin transport in various plant species is poorly understood. Currently, no information is available about this gene family in wheat (Triticum aestivum L.). In the present investigation, we identified the PIN gene family in wheat to understand the evolution of PIN-mediated auxin transport and its role in various developmental processes and under different biotic and abiotic stress conditions. In this study, we performed genome-wide analysis of the PIN gene family in common wheat and identified 44 TaPIN genes through a homology search, further characterizing them to understand their structure, function, and distribution across various tissues. Phylogenetic analyses led to the classification of TaPIN genes into seven different groups, providing evidence of an evolutionary relationship with Arabidopsis thaliana and Oryza sativa. A gene exon/intron structure analysis showed a distinct evolutionary path and predicted the possible gene duplication events. Further, the physical and biochemical properties, conserved motifs, chromosomal, subcellular localization, transmembrane domains, and three-dimensional (3D) structure were also examined using various computational approaches. Cis-elements analysis of TaPIN genes showed that TaPIN promoters consist of phytohormone, plant growth and development, and stress-related cis-elements. In addition, expression profile analysis also revealed that the expression patterns of the TaPIN genes were different in different tissues and developmental stages. Several members of the TaPIN family were induced during biotic and abiotic stress. Moreover, the expression patterns of TaPIN genes were verified by qRT-PCR. The qRT-PCR results also show a similar expression with slight variation. Therefore, the outcome of this study provides basic genomic information on the expression of the TaPIN gene family and will pave the way for dissecting the precise role of TaPINs in plant developmental processes and different stress conditions.
PMID: 34299014
Int J Mol Sci , IF:5.923 , 2021 Jul , V22 (14) doi: 10.3390/ijms22147313
Analysis of Phytohormone Signal Transduction in Sophora alopecuroides under Salt Stress.
College of Plant Science, Jilin University, Xi'an Road, Changchun 130062, China.
Salt stress seriously restricts crop yield and quality, leading to an urgent need to understand its effects on plants and the mechanism of plant responses. Although phytohormones are crucial for plant responses to salt stress, the role of phytohormone signal transduction in the salt stress responses of stress-resistant species such as Sophora alopecuroides has not been reported. Herein, we combined transcriptome and metabolome analyses to evaluate expression changes of key genes and metabolites associated with plant hormone signal transduction in S. alopecuroides roots under salt stress for 0 h to 72 h. Auxin, cytokinin, brassinosteroid, and gibberellin signals were predominantly involved in regulating S. alopecuroides growth and recovery under salt stress. Ethylene and jasmonic acid signals may negatively regulate the response of S. alopecuroides to salt stress. Abscisic acid and salicylic acid are significantly upregulated under salt stress, and their signals may positively regulate the plant response to salt stress. Additionally, salicylic acid (SA) might regulate the balance between plant growth and resistance by preventing reduction in growth-promoting hormones and maintaining high levels of abscisic acid (ABA). This study provides insight into the mechanism of salt stress response in S. alopecuroides and the corresponding role of plant hormones, which is beneficial for crop resistance breeding.
PMID: 34298928
Int J Mol Sci , IF:5.923 , 2021 Jul , V22 (14) doi: 10.3390/ijms22147305
Coumarin Interferes with Polar Auxin Transport Altering Microtubule Cortical Array Organization in Arabidopsis thaliana (L.) Heynh. Root Apical Meristem.
Dipartimento di Biologia, Ecologia e Scienza della Terra, Universita della Calabria (DiBEST-UNICAL), 87036 Arcavacata di Rende, Italy.; Department of Plant Biology and Soil Science, Campus Lagoas-Marcosende, University of Vigo, 36310 Vigo, Spain.; CITACA, Agri-Food Research and Transfer Cluster, Campus da Auga, University of Vigo, 32004 Ourense, Spain.; Department for Sustainable Food Process, Universita Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy.; Department of European and Mediterranean Cultures: Architecture, Environment, and Cultural Heritage (DICEM), University of Basilicata, 75100 Matera, Italy.; Dipartimento di Scienze Agrarie e Ambientali-Produzione, Territorio, Agroenergia, Universita Statale di Milano, Via Celoria n degrees 2, 20133 Milano, Italy.
Coumarin is a phytotoxic natural compound able to affect plant growth and development. Previous studies have demonstrated that this molecule at low concentrations (100 microM) can reduce primary root growth and stimulate lateral root formation, suggesting an auxin-like activity. In the present study, we evaluated coumarin's effects (used at lateral root-stimulating concentrations) on the root apical meristem and polar auxin transport to identify its potential mode of action through a confocal microscopy approach. To achieve this goal, we used several Arabidopsis thaliana GFP transgenic lines (for polar auxin transport evaluation), immunolabeling techniques (for imaging cortical microtubules), and GC-MS analysis (for auxin quantification). The results highlighted that coumarin induced cyclin B accumulation, which altered the microtubule cortical array organization and, consequently, the root apical meristem architecture. Such alterations reduced the basipetal transport of auxin to the apical root apical meristem, inducing its accumulation in the maturation zone and stimulating lateral root formation.
PMID: 34298924
Front Plant Sci , IF:5.753 , 2021 , V12 : P700555 doi: 10.3389/fpls.2021.700555
Differential Contributions of MYCs to Insect Defense Reveals Flavonoids Alleviating Growth Inhibition Caused by Wounding in Arabidopsis.
CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.; School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.; University of Chinese Academy of Sciences, Beijing, China.
In Arabidopsis, basic helix-loop-helix transcription factors (TFs) MYC2, MYC3, and MYC4 are involved in many biological processes, such as defense against insects. We found that despite functional redundancy, MYC-related mutants displayed different resistance to cotton bollworm (Helicoverpa armigera). To screen out the most likely genes involved in defense against insects, we analyzed the correlation of gene expression with cotton bollworm resistance in wild-type (WT) and MYC-related mutants. In total, the expression of 94 genes in untreated plants and 545 genes in wounded plants were strongly correlated with insect resistance, and these genes were defined as MGAIs (MYC-related genes against insects). MYC3 had the greatest impact on the total expression of MGAIs. Gene ontology (GO) analysis revealed that besides the biosynthesis pathway of glucosinolates (GLSs), MGAIs, which are well-known defense compounds, were also enriched in flavonoid biosynthesis. Moreover, MYC3 dominantly affected the gene expression of flavonoid biosynthesis. Weighted gene co-expression network analysis (WGCNA) revealed that AAE18, which is involved in activating auxin precursor 2,4-dichlorophenoxybutyric acid (2,4-DB) and two other auxin response genes, was highly co-expressed with flavonoid biosynthesis genes. With wounding treatment, the WT plants exhibited better growth performance than chalcone synthase (CHS), which was defective in flavonoid biosynthesis. The data demonstrated dominant contributions of MYC3 to cotton bollworm resistance and imply that flavonoids might alleviate the growth inhibition caused by wounding in Arabidopsis.
PMID: 34326858
Front Plant Sci , IF:5.753 , 2021 , V12 : P680859 doi: 10.3389/fpls.2021.680859
Efficient Protoplast Regeneration Protocol and CRISPR/Cas9-Mediated Editing of Glucosinolate Transporter (GTR) Genes in Rapeseed (Brassica napus L.).
Department of Plant Breeding, Swedish University of Agricultural Sciences, Lomma, Sweden.
Difficulty in protoplast regeneration is a major obstacle to apply the CRISPR/Cas9 gene editing technique effectively in research and breeding of rapeseed (Brassica napus L.). The present study describes for the first time a rapid and efficient protocol for the isolation, regeneration and transfection of protoplasts of rapeseed cv. Kumily, and its application in gene editing. Protoplasts isolated from leaves of 3-4 weeks old were cultured in MI and MII liquid media for cell wall formation and cell division, followed by subculture on shoot induction medium and shoot regeneration medium for shoot production. Different basal media, types and combinations of plant growth regulators, and protoplast culture duration on each type of media were investigated in relation to protoplast regeneration. The results showed that relatively high concentrations of NAA (0.5 mg l(-1)) and 2,4-D (0.5 mg l(-1)) in the MI medium were essential for protoplasts to form cell walls and maintain cell divisions, and thereafter auxin should be reduced for callus formation and shoot induction. For shoot regeneration, relatively high concentrations of cytokinin were required, and among all the combinations tested, 2.2 mg l(-1) TDZ in combination with auxin 0.5 mg l(-1) NAA gave the best result with up to 45% shoot regeneration. Our results also showed the duration of protoplast culture on different media was critical, as longer culture durations would significantly reduce the shoot regeneration frequency. In addition, we have optimized the transfection protocol for rapeseed. Using this optimized protocol, we have successfully edited the BnGTR genes controlling glucosinolate transport in rapeseed with a high mutation frequency.
PMID: 34305978
Front Plant Sci , IF:5.753 , 2021 , V12 : P659645 doi: 10.3389/fpls.2021.659645
Seasonal Variation in Transcriptomic Profiling of Tetrastigma hemsleyanum Fully Developed Tuberous Roots Enriches Candidate Genes in Essential Metabolic Pathways and Phytohormone Signaling.
Department of Biotechnology, College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, China.; Laboratory of Plant Molecular Biology and Biotechnology, Department of Biology, The University of North Carolina at Greensboro, Greensboro, NC, United States.
Tetrastigma hemsleyanum Diels et Gilg (Sanyeqing, SYQ) is a perennial climbing liana and an endemic plant to southern China. Its tuberous roots (TRs) are used in traditional Chinese medicine for treating some diseases such as high fever, pneumonia, asthma, hepatitis, and cancers. However, the mechanisms underlying the development of TR and the content of flavonoids and phenylpropanoids (FPs) are not well-understood. In this study, we performed a transcriptomic analysis of 12 fully developed TR (FD-TR) samples harvested in four seasons [spring (Sp), summer (Su), autumn (Au), and winter (Wi)] using the RNA-Sequencing (RNA-Seq). We obtained a total of 78.54 Gb raw data and 65,578 unigenes. Then, the unigenes were annotated by using six databases such as non-redundant protein database (NR), Pfam, eggNOG, SWISSProt, Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene ontology (GO). The transcriptomic profiling showed closer relationships between the samples obtained in Su and Au than those obtained in Sp and Wi based on the results of both total unigenes and differentially expressed genes (DEGs). Three pathways, including the biosynthesis of FPs, metabolism of starch and sucrose, and signaling of phytohormones, were highly enriched, suggesting a gene-level seasonal variation. Based on the numbers of DEGs, brassinosteroid (BR) signal transduction factors appeared to play a key role in modulating the development of TRs while most of the auxin signaling genes were mainly activated in Wi and Sp FD-TRs. Most genes in the biosynthesis and biodegradation of starch and biodegradation of cellulose were activated in Wi FD-TRs. As determined by the high performance liquid chromatography (HPLC) and aluminum nitrate colorimetric method, the contents of total flavonoids and most detected FP components increased from Sp to Au but decreased in Wi. Enhanced expression levels of some genes in the biosynthetic pathways of FPs were detected in Su and Au samples, which corroborated well with metabolite content. Our findings provide the first transcriptomic and biochemical data on a seasonal variation in the composition of medically important metabolites in SYQ FD-TRs.
PMID: 34305963
FEBS J , IF:5.542 , 2021 Jul doi: 10.1111/febs.16132
Meet your MAKR: the MEMBRANE ASSOCIATED KINASE REGULATOR protein family in the regulation of plant development.
Department of Plant Molecular Biology, Biophore Building, University of Lausanne, CH-1015, Lausanne, Switzerland.; Institute of Cytology and Genetics, Novosibirsk, Russian Federation.; Novosibirsk State University, Novosibirsk, Russian Federation.; Department of Plant Systems Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands.; Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, Ecole normale superieure de Lyon, Universite Claude Bernard Lyon 1, CNRS, INRAE, Lyon, 69342, France.
A small family composed of BRI1 KINASE INHIBITOR1 (BKI1) and MEMBRANE ASSOCIATED KINASE REGULATORs (MAKRs) has recently captured the attention of plant biologists, due to their involvement in developmental processes downstream of hormones and Receptor-Like Kinases (RLK) signaling. BKI1/MAKRs are intrinsically disordered proteins (so-called unstructured proteins) and as such lack specific domains. Instead, they are defined by the presence of two conserved linear motifs involved in the interaction with lipids and proteins, respectively. Here, we first relate the discovery of the MAKR gene family. Then, we review the individual function of characterized family members and discuss their shared and specific modes of action. Finally, we explore and summarize the structural, comparative, and functional genomics data available on this gene family. Together, this review aims at building a comprehensive reference about BKI1/MAKR protein function in plants.
PMID: 34288456
Plant Cell Physiol , IF:4.927 , 2021 Jul doi: 10.1093/pcp/pcab107
Components and Functional Diversification of Florigen Activation Complexes in Cotton.
College of Life Sciences, Shihezi University, Shihezi 832003, China.; Center for Crop Biotechnology, College of Agriculture, Anhui Science and Technology University, Fengyang 233100, China.; Plant Genomics Laboratory, College of Life Sciences, Shihezi University, Shihezi 832003, China.
In shoot apex cells of rice, a hexameric florigen activation complex (FAC), comprising FLOWERING LOCUS T (FT), 14-3-3 and the bZIP transcription factor FD, activates downstream target genes and regulates several developmental transitions, including flowering. The allotetraploid cotton (Gossypium hirsutum L.) contains only one FT locus in both of the A- and D-subgenomes. However, there is limited information regarding cotton FACs. Here, we identified a 14-3-3 protein that interacts strongly with GhFT in the cytoplasm and nuclei, and five FD homoeologous gene pairs were characterized. In vivo, all five GhFD proteins interacted with Gh14-3-3 and GhFT in the nucleus. GhFT, 14-3-3, and all the GhFDs interacted in the nucleus as well, suggesting that they formed a ternary complex. Virus-induced silencing of GhFD1, -2, and -4 in cotton delayed flowering and inhibited the expression of floral meristem identity genes. Silencing GhFD3 strongly decreased lateral root formation, suggesting a function in lateral root development. GhFD overexpression in Arabidopsis and transcriptional activation assays suggested that FACs containing GhFD1 and GhFD2 function mainly in promoting flowering with partial functional redundancy. Moreover, GhFD3 was specifically expressed in lateral root meristems and dominantly activated the transcription of AUXIN RESPONSE FACTOR genes, such as ARF19. Thus, the diverse functions of FACs may depend on the recruited GhFD. Creating targeted genetic mutations in the florigen system using CRISPR-Cas genome editing may fine-tune flowering and improve plant architecture.
PMID: 34245289
Plant Cell Physiol , IF:4.927 , 2021 Jul doi: 10.1093/pcp/pcab101
Transcriptome Dynamics of Epidermal Reprogramming during Direct Shoot Regeneration in Torenia fournieri.
Botanical Gardens, Graduate School of Science, The University of Tokyo, 3-7-1 Hakusan, Bunkyo-ku, Tokyo 112-0001, Japan.; Department of Biological Science, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan.; Department of Biological Chemistry, College of Bioscience Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.; Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.; Department of Biology, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan.; Institute of Transformative Bio-Molecules (WPI-ITbM), Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Shoot regeneration involves reprogramming of somatic cells and de novo organization of shoot apical meristems (SAMs). In the best-studied model system of shoot regeneration using Arabidopsis, regeneration occurs mediated by auxin-responsive pluripotent callus formation from pericycle or pericycle-like tissues according to the lateral root development pathway. In contrast, shoot regeneration can be induced directly from fully differentiated epidermal cells of stem explants of Torenia fournieri (Torenia) without intervening callus mass formation in culture with cytokinin, yet its molecular mechanisms remain unaddressed. Here we characterized this direct shoot regeneration by cytological observation and transcriptome analyses. The results showed that the gene expression profile rapidly changes upon culture to acquire a mixed signature of multiple organs/tissues, possibly associated with epidermal reprogramming. Comparison of transcriptomes between three different callus-inducing cultures (callus induction by auxin, callus induction by wounding, and protoplast culture) of Arabidopsis and the Torenia stem culture identified genes upregulated in all the four culture systems as candidates of common factors of cell reprogramming. These initial changes proceeded independently of cytokinin, followed by cytokinin-dependent, transcriptional activations of nucleolar development and cell cycle. Later, SAM regulatory genes became highly expressed, leading to SAM organization in the foci of proliferating cells in the epidermal layer. Our findings revealed three distinct phases with different transcriptomic and regulatory features during direct shoot regeneration from the epidermis in Torenia, which provides a basis for further investigation of shoot regeneration in this unique culture system.
PMID: 34223624
Plant Cell Physiol , IF:4.927 , 2021 Jul , V62 (3) : P458-471 doi: 10.1093/pcp/pcab002
S-nitrosoglutathione Reductase-Mediated Nitric Oxide Affects Axillary Buds Outgrowth of Solanum lycopersicum L. by Regulating Auxin and Cytokinin Signaling.
State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Taian 271018, P.R. China.
Auxin and cytokinin are two kinds of important phytohormones that mediate outgrowth of axillary buds in plants. How nitric oxide and its regulator of S-nitrosoglutathione reductase (GSNOR) take part in auxin and cytokinin signaling for controlling axillary buds outgrowth remains elusive. We investigated the roles of GSNOR during tomato axillary bud outgrowth by using physiological, biochemical and genetic approaches. GSNOR negatively regulated NO homeostasis. Suppression of GSNOR promoted axillary bud outgrowth by inhibiting the expression of FZY in both apical and axillary buds. Meanwhile, AUX1 and PIN1 were down-regulated in apical buds but up-regulated in axillary buds in GSNOR-suppressed plants. Thus, reduced IAA accumulation was shown in both apical buds and axillary buds of GSNOR-suppressed plants. GSNOR-mediated changes of NO and auxin affected cytokinin biosynthesis, transport, and signaling. And a decreased ratio of auxin: cytokinin was shown in axillary buds of GSNOR-suppressed plants, leading to bud dormancy breaking. We also found that the original NO signaling was generated by nitrate reductase (NR) catalyzing nitrate as substrate. NR-mediated NO reduced the GSNOR activity through S-nitrosylation of Cys-10, then induced a further NO burst, which played the above roles to promote axillary buds outgrowth. Together, GSNOR-mediated NO played important roles in controlling axillary buds outgrowth by altering the homeostasis and signaling of auxin and cytokinin in tomato plants.
PMID: 33493306
Plant Sci , IF:4.729 , 2021 Sep , V310 : P110993 doi: 10.1016/j.plantsci.2021.110993
Transcription factor SmSPL7 promotes anthocyanin accumulation and negatively regulates phenolic acid biosynthesis in Salvia miltiorrhiza.
Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest of China, Shaanxi Normal University, Xi'an 710062, China.; College of Life Science, Luoyang Normal University, Luoyang 471934, China.; Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest of China, Shaanxi Normal University, Xi'an 710062, China. Electronic address: caoxiaoyan@snnu.edu.cn.
Plant-specific SQUAMOSA promoter-binding protein-like (SPL) transcription factors play critical regulatory roles during plant growth and development. However, the functions of SPLs in Salvia miltiorrhiza (SmSPLs; a model medicinal plant) have not been reported. Here, the expression patterns and functions of SmSPL7 were characterized in S. miltiorrhiza. SmSPL7 was expressed in all parts of S. miltiorrhiza, with the highest expression level in the leaves, and could be inhibited by multiple hormones, including methyl jasmonate, auxin, abscisic acid, and gibberellin. SmSPL7 is localized within the nucleus and exhibits robust transcriptional activation activity. Transgenic lines overexpressing SmSPL7 demonstrated pronounced growth inhibition, accompanied by increased anthocyanin accumulation via the genetic activation of the anthocyanin biosynthesis pathway. However, SmSPL7 overexpression significantly decreased salvianolic acid B (SalB) production by inhibiting the transcripts of genes implicated in its biosynthesis pathway. Further analysis indicated that SmSPL7 directly binds to SmTAT1 and Sm4CL9 promoters and blocks their expression to inhibit the biosynthesis of SalB. Taken together, these results indicate that SmSPL7 is a negative regulator of SalB biosynthesis but positively regulates anthocyanin accumulation in S. miltiorrhiza. These findings provide new insights into the functionality of the SPL family while establishing an important foundation for further uncovering the crucial roles of SmSPL7 in the growth of S. miltiorrhiza.
PMID: 34315580
Sci Rep , IF:4.379 , 2021 Jul , V11 (1) : P13745 doi: 10.1038/s41598-021-93303-8
Rhizobacteria from 'flowering desert' events contribute to the mitigation of water scarcity stress during tomato seedling germination and growth.
Programa de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Ave. Francisco Salazar, 01145, Temuco, Chile.; Laboratorio de Ecologia Microbiana Aplicada (EMALAB), Departamento de Ciencias Quimica y Recursos Naturales, Universidad de La Frontera, Ave. Francisco Salazar, 01145, Temuco, Chile.; The Network for Extreme Environment Research (NEXER), Scientific and Biotechnological Bioresources Nucleus, Universidad de La Frontera, Ave. Francisco Salazar, 01145, Temuco, Chile.; Department of Soil, Water, and Climate, and Department of Plant and Microbial Biology, and BioTechnology Institute, University of Minnesota, 1479 Gortner Ave., St. Paul, MN, 55108, USA.; Laboratorio de Ecologia Microbiana Aplicada (EMALAB), Departamento de Ciencias Quimica y Recursos Naturales, Universidad de La Frontera, Ave. Francisco Salazar, 01145, Temuco, Chile. milko.jorquera@ufrontera.cl.; The Network for Extreme Environment Research (NEXER), Scientific and Biotechnological Bioresources Nucleus, Universidad de La Frontera, Ave. Francisco Salazar, 01145, Temuco, Chile. milko.jorquera@ufrontera.cl.
Tomato (Solanum lycopersicum L.) is an important vegetable cultivated around the world. Under field conditions, tomato can be negatively affected by water scarcity in arid and semiarid regions. The application of native plant growth-promoting rhizobacteria (PGPR) isolated from arid environments has been proposed as an inoculant to mitigate abiotic stresses in plants. In this study, we evaluated rhizobacteria from Cistanthe longiscapa (syn Calandrinia litoralis and Calandrinia longiscapa), a representative native plant of flowering desert (FD) events (Atacama Desert, Chile), to determine their ability to reduce water scarcity stress on tomato seedlings. The isolated bacterial strains were characterized with respect to their PGPR traits, including P solubilization, 1-aminocyclopropane-1-carboxylate deaminase activity, and tryptophan-induced auxin and exopolysaccharide production. Three PGPR consortia were formulated with isolated Bacillus strains and then applied to tomato seeds, and then, the seedlings were exposed to different levels of water limitations. In general, tomato seeds and seedlings inoculated with the PGPR consortia presented significantly (P
PMID: 34215802
Ann Bot , IF:4.357 , 2021 Jul , V128 (2) : P137-148 doi: 10.1093/aob/mcab052
Stomatal development in the context of epidermal tissues.
Howard Hughes Medical Institute and Department of Molecular Biosciences, The University of Texas at Austin, AustinTX, USA.; Institute of Transformative Biomolecules (WPI-ITbM), Nagoya University, Nagoya, Aichi, Japan.
BACKGROUND: Stomata are adjustable pores on the surface of plant shoots for efficient gas exchange and water control. The presence of stomata is essential for plant growth and survival, and the evolution of stomata is considered as a key developmental innovation of the land plants, allowing colonization on land from aquatic environments some 450 million years ago. In the past two decades, molecular genetic studies using the model plant Arabidopsis thaliana identified key genes and signalling modules that regulate stomatal development: master regulatory transcription factors that orchestrate cell state transitions and peptide-receptor signal transduction pathways, which, together, enforce proper patterning of stomata within the epidermis. Studies in diverse plant species, ranging from bryophytes to angiosperm grasses, have begun to unravel the conservation and uniqueness of the core modules in stomatal development. SCOPE: Here, I review the mechanisms of stomatal development in the context of epidermal tissue patterning. First, I introduce the core regulatory mechanisms of stomatal patterning and differentiation in the model species A. thaliana. Subsequently, experimental evidence is presented supporting the idea that different cell types within the leaf epidermis, namely stomata, hydathodes pores, pavement cells and trichomes, either share developmental origins or mutually influence each other's gene regulatory circuits during development. Emphasis is placed on extrinsic and intrinsic signals regulating the balance between stomata and pavement cells, specifically by controlling the fate of stomatal-lineage ground cells (SLGCs) to remain within the stomatal cell lineage or differentiate into pavement cells. Finally, I discuss the influence of intertissue layer communication between the epidermis and underlying mesophyll/vascular tissues on stomatal differentiation. Understanding the dynamic behaviours of stomatal precursor cells and their differentiation in the broader context of tissue and organ development may help design plants tailored for optimal growth and productivity in specific agricultural applications and a changing environment.
PMID: 33877316
Environ Sci Pollut Res Int , IF:4.223 , 2021 Jul doi: 10.1007/s11356-021-15382-4
Biosorption effect of Aspergillus niger and Penicillium chrysosporium for Cd- and Pb-contaminated soil and their physiological effects on Vicia faba L.
Biological and Geological Sciences Department, Faculty of Education, Ain Shams University, El Makres St. Roxy, Cairo, 11341, Egypt.; Biological and Geological Sciences Department, Faculty of Education, Ain Shams University, El Makres St. Roxy, Cairo, 11341, Egypt. hebaibrahim79@gmail.com.
Phytoremediation is an important solution to soil pollution management. The goal of this study is to determine the biosorption ability of the two selected fungi (Aspergillus niger and Penicillium chrysosporium) under heavy metal stress on faba bean plants. The fungal strains produced phytohormones, siderophore, ACC deaminase, and secondary metabolites. The biosorption capacity of A. niger and P. chrysosporium was 0.09 and 0.06 mg g(-1) and 0.5 and 0.4 mg g(-1) in media containing Cd and Pb, respectively. Fourier transform infrared spectroscopy of the fungal cell wall show primary functional groups like hydroxyl, amide, carboxyl, phosphoryl, sulfhydryl, and nitro. Therefore, A. niger and P. chrysosporium were inoculated to soils, and then the faba bean seeds were sown. After 21 days of sowing, the plants were irrigated with water to severe as control, with 100 mg L(-1) of Cd and 200 mg L(-1) of Pb. The results show that Cd and Pb caused a significant reduction in morphological characteristics, auxin, gibberellins, photosynthetic pigments, minerals content, and antioxidant enzymes as compared to control plants but caused a substantial boost in abscisic acid, ethylene, electrolyte leakage, lipid peroxidation, glutathione, proline, superoxide dismutase, secondary metabolites, and antioxidant capacity. In inoculated plants, metal-induced oxidative stress was modulated by inhibiting the transport of metal and decreased electrolyte leakage and lipid peroxidation. Finally, the inoculation of endophytic fungi contributed actively to the absorption of heavy metals and decreased their content in soil and plants. This could be utilized as an excellent technique in the fields of heavy metal-contaminated sustainable agriculture.
PMID: 34258698
Environ Sci Pollut Res Int , IF:4.223 , 2021 Jul doi: 10.1007/s11356-021-15087-8
Brassinosteroids as a multidimensional regulator of plant physiological and molecular responses under various environmental stresses.
Institute of Crop Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.; Institute of Crop Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China. vcguan@zju.edu.cn.
Biotic and abiotic stresses, especially heavy metal toxicity, are becoming a big problem in agriculture, which pose serious threats to crop production. Plant hormones have recently been used to develop stress tolerance in a variety of plants. Brassinosteroids (BRs) are the sixth class of plant steroid hormones, with pleiotropic effects on plants. Exogenous application of BRs to boost plant tolerance mechanisms to various stresses has been a major research focus. Numerous studies have revealed the role of these steroidal hormones in the up-regulation of stress-related resistance genes, as well as their interactions with other metabolic pathways. BRs interact with other phytohormones such as auxin, cytokinin, ethylene, gibberellin, jasmonic acid, abscisic acid, salicylic acid, and polyamines to regulate a variety of physiological and developmental processes in plants. BRs regulate expressions of many BR-inducible genes by activating the brassinazole-resistant 1 (BZR1)/BRI1-EMS suppressor 1 (BES1) complex. Moreover, to improve plant development under a variety of stresses, BRs regulate antioxidant enzyme activity, chlorophyll concentration, photosynthetic capability, and glucose metabolism. This review will provide insights into the mechanistic role and actions of brassinosteroids in plants in response to various stresses.
PMID: 34235688
BMC Plant Biol , IF:4.215 , 2021 Jul , V21 (1) : P327 doi: 10.1186/s12870-021-03110-6
Transcriptomic analysis of temporal shifts in berry development between two grapevine cultivars of the Pinot family reveals potential genes controlling ripening time.
Genetics and Genomics of Plants, Faculty of Biology & Center for Biotechnology, Bielefeld University, Bielefeld, Germany.; Julius Kuhn-Institute, Institute for Grapevine Breeding Geilweilerhof, Siebeldingen, Germany.; Genetics and Genomics of Plants, Faculty of Biology & Center for Biotechnology, Bielefeld University, Bielefeld, Germany. bernd.weisshaar@uni-bielefeld.de.
BACKGROUND: Grapevine cultivars of the Pinot family represent clonally propagated mutants with major phenotypic and physiological differences, such as different colour or shifted ripening time, as well as changes in important viticultural traits. Specifically, the cultivars 'Pinot Noir' (PN) and 'Pinot Noir Precoce' (PNP, early ripening) flower at the same time, but vary in the beginning of berry ripening (veraison) and, consequently, harvest time. In addition to genotype, seasonal climatic conditions (i.e. high temperatures) also affect ripening times. To reveal possible regulatory genes that affect the timing of veraison onset, we investigated differences in gene expression profiles between PN and PNP throughout berry development with a closely meshed time series and over two separate years. RESULTS: The difference in the duration of berry formation between PN and PNP was quantified to be approximately two weeks under the growth conditions applied, using plant material with a proven PN and PNP clonal relationship. Clusters of co-expressed genes and differentially expressed genes (DEGs) were detected which reflect the shift in the timing of veraison onset. Functional annotation of these DEGs fit to observed phenotypic and physiological changes during berry development. In total, we observed 3,342 DEGs in 2014 and 2,745 DEGs in 2017 between PN and PNP, with 1,923 DEGs across both years. Among these, 388 DEGs were identified as veraison-specific and 12 were considered as berry ripening time regulatory candidates. The expression profiles revealed two candidate genes for ripening time control which we designated VviRTIC1 and VviRTIC2 (VIT_210s0071g01145 and VIT_200s0366g00020, respectively). These genes likely contribute the phenotypic differences observed between PN and PNP. CONCLUSIONS: Many of the 1,923 DEGs show highly similar expression profiles in both cultivars if the patterns are aligned according to developmental stage. In our work, putative genes differentially expressed between PNP and PN which could control ripening time as well as veraison-specific genes were identified. We point out connections of these genes to molecular events during berry development and discuss potential candidate genes which may control ripening time. Two of these candidates were observed to be differentially expressed in the early berry development phase. Several down-regulated genes during berry ripening are annotated as auxin response factors / ARFs. Conceivably, general changes in auxin signaling may cause the earlier ripening phenotype of PNP.
PMID: 34233614
BMC Plant Biol , IF:4.215 , 2021 Jul , V21 (1) : P316 doi: 10.1186/s12870-021-03086-3
Reprogramming of the wheat transcriptome in response to infection with Claviceps purpurea, the causal agent of ergot.
NIAB, 93 Lawrence Weaver Road, Cambridge, CB3 0LE, UK.; Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.; Philippine Genome Center, Plant Physiology Laboratory, Institute of Plant Breeding, University of the Philippines, Los Banos, Laguna, The Philippines.; Present Address: Microsoft Research, 21 Station Road, Cambridge, CB1 2FB, UK.; School of Agriculture, Policy and Development, University of Reading, Whiteknights, Reading, RG6 6AR, UK.; NIAB, 93 Lawrence Weaver Road, Cambridge, CB3 0LE, UK. lesley.boyd@niab.com.
BACKGROUND: Ergot, caused by the fungal pathogen Claviceps purpurea, infects the female flowers of a range of cereal crops, including wheat. To understand the interaction between C. purpurea and hexaploid wheat we undertook an extensive examination of the reprogramming of the wheat transcriptome in response to C. purpurea infection through floral tissues (i.e. the stigma, transmitting and base ovule tissues of the ovary) and over time. RESULTS: C. purpurea hyphae were observed to have grown into and down the stigma at 24 h (H) after inoculation. By 48H hyphae had grown through the transmitting tissue into the base, while by 72H hyphae had surrounded the ovule. By 5 days (D) the ovule had been replaced by fungal tissue. Differential gene expression was first observed at 1H in the stigma tissue. Many of the wheat genes differentially transcribed in response to C. purpurea infection were associated with plant hormones and included the ethylene (ET), auxin, cytokinin, gibberellic acid (GA), salicylic acid and jasmonic acid (JA) biosynthetic and signaling pathways. Hormone-associated genes were first detected in the stigma and base tissues at 24H, but not in the transmitting tissue. Genes associated with GA and JA pathways were seen in the stigma at 24H, while JA and ET-associated genes were identified in the base at 24H. In addition, several defence-related genes were differential expressed in response to C. purpurea infection, including antifungal proteins, endocytosis/exocytosis-related proteins, NBS-LRR class proteins, genes involved in programmed cell death, receptor protein kinases and transcription factors. Of particular interest was the identification of differential expression of wheat genes in the base tissue well before the appearance of fungal hyphae, suggesting that a mobile signal, either pathogen or plant-derived, is delivered to the base prior to colonisation. CONCLUSIONS: Multiple host hormone biosynthesis and signalling pathways were significantly perturbed from an early stage in the wheat - C. purpurea interaction. Differential gene expression at the base of the ovary, ahead of arrival of the pathogen, indicated the potential presence of a long-distance signal modifying host gene expression.
PMID: 34215204
Tree Physiol , IF:4.196 , 2021 Jul doi: 10.1093/treephys/tpab102
The meristem-associated endosymbiont Methylorubrum extorquens DSM13060 reprograms development and stress responses of pine seedlings.
Ecology and Genetics, University of Oulu, PO Box 3000, FIN-90014 Oulu, Finland.; Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.; Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany.; Institute of Molecular Biology and Genetics of NASU, Acad. Zabolotnoho str., 150 03680 Kyiv, Ukraine.; Weiden am See, Burgenland, Austria.; Nature Resources Institute Finland, Vipusenkuja 5, 57200 Savonlinna, Finland.
Microbes living in plant tissues, endophytes, are mainly studied in crop plants where they typically colonize the root apoplast. Trees, a large carbon source with a high capacity for photosynthesis, provide a variety of niches for endophytic colonization. We have earlier identified a new type of plant-endophyte interaction in buds of adult Scots pine, where Methylorubrum species live inside the meristematic cells. The endosymbiont M. extorquens DSM13060 significantly increases needle and root growth of pine seedlings without producing plant hormones, but by aggregating around host nuclei. Here we studied gene expression and metabolites of the pine host induced by M. extorquens DSM13060 infection. Malic acid was produced by pine to potentially boost M. extorquens colonization and interaction. Based on gene expression, the endosymbiont activated the auxin- and ethylene (ET)-associated hormonal pathways through induction of CUL1 and HYL1, and suppressed salicylic and abscisic acid signaling of pine. Infection by the endosymbiont had an effect on pine meristem and leaf development through activation of GLP1-7 and ALE2, and suppressed flowering, root hair and lateral root formation by down-regulation of AGL8, plantacyanin, GASA7, COW1 and RALFL34. Despite of systemic infection of pine seedlings by the endosymbiont, the pine genes CUL1, ETR2, ERF3, HYL, GLP1-7, and CYP71 were highly expressed in the shoot apical meristem, rarely in needles, and not in stem or root tissues. Low expression of MERI5, CLH2, EULS3, and high quantities of ononitol suggest that endosymbiont promotes viability and protects pine seedlings against abiotic stress. Our results indicate that the endosymbiont positively affects host development and stress tolerance through mechanisms previously unknown for endophytic bacteria, manipulation of plant hormone signaling pathways, down-regulation of senescence and cell death-associated genes, and induction of ononitol biosynthesis.
PMID: 34328183
Tree Physiol , IF:4.196 , 2021 Jul , V41 (7) : P1247-1263 doi: 10.1093/treephys/tpaa180
UV-B-induced molecular mechanisms of stress physiology responses in the major northern Chinese conifer Pinus tabuliformis Carr.
Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, National Engineering Laboratory for Tree Breeding, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, 35 Qinghua E Rd, Beijing 100083, China.; Department of Ecology and Environmental Science, Umea Plant Science Centre, Umea University, SE-901 87 Umea, Sweden.; Qigou State-owned Forest Farm, Qigou Village, Qigou Town, Pingquan County, Chengde City, Hebei Province, 067509, China.; Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4 Canada.; Department des Sciences du Bois et de la Foret, Faculte de Foresterie, de Geographie et Geomatique, Universite Laval Quebec, 1030 Avenue de la Medecine, Quebec, QC G1V 0A6, Canada.
During their lifetimes, plants are exposed to different abiotic stress factors eliciting various physiological responses and triggering important defense processes. For UV-B radiation responses in forest trees, the genetics and molecular regulation remain to be elucidated. Here, we exposed Pinus tabuliformis Carr., a major conifer from northern China, to short-term high-intensity UV-B and employed a systems biology approach to characterize the early physiological processes and the hierarchical gene regulation, which revealed a temporal transition from primary to secondary metabolism, the buildup of enhanced antioxidant capacity and stress-signaling activation. Our findings showed that photosynthesis and biosynthesis of photosynthetic pigments were inhibited, while flavonoids and their related derivates biosynthesis, as well as glutathione and glutathione S-transferase mediated antioxidant processes, were enhanced. Likewise, stress-related phytohormones (jasmonic acid, salicylic acid and ethylene), kinase and reactive oxygen species signal transduction pathways were activated. Biological processes regulated by auxin and karrikin were, for the first time, found to be involved in plant defense against UV-B by promoting the biosynthesis of flavonoids and the improvement of antioxidant capacity in our research system. Our work evaluated the physiological and transcriptome perturbations in a conifer's response to UV-B, and generally, highlighted the necessity of a systems biology approach in addressing plant stress biology.
PMID: 33416074
Mol Plant Microbe Interact , IF:4.171 , 2021 Jul : PMPMI08200240R doi: 10.1094/MPMI-08-20-0240-R
Proteomic Analysis Demonstrates a Molecular Dialog Between Trichoderma guizhouense NJAU 4742 and Cucumber (Cucumis sativus L) Roots: Role in Promoting Plant Growth.
Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China.
Trichoderma is a genus of filamentous fungi that play notable roles in stimulating plant growth after colonizing the root surface. However, the key proteins and molecular mechanisms governing this stimulation have not been completely elucidated. In this study, Trichoderma guizhouense NJAU 4742 was investigated in a hydroponic culture system after interacting with cucumber roots. The total proteins of the fungus were characterized, and the key metabolic pathways along with related genes were analyzed through proteomic and transcriptomic analyses. The roles played by the regulated proteins during the interaction between plants and NJAU 4742 were further examined. The intracellular or extracellular proteins from NJAU 4742 and extracellular proteins from cucumber were quantified, and the high-abundance proteins were determined which were primarily involved in the shikimate pathway (tryptophan, tyrosine, and phenylalanine metabolism, auxin biosynthesis, and secondary metabolite synthesis). Moreover, (15)N-KNO3 labeling analysis indicated that NJAU 4742 had a strong ability to convert nitrogenous amino acids, nitrate, nitrile, and amines into ammonia. The auxin synthesis and ammonification metabolism pathways of NJAU 4742 significantly contributed to plant growth. The results of this study demonstrated the crucial metabolic pathways involved in the interactions between Trichoderma spp. and plants. [Formula: see text] Copyright (c) 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
PMID: 33496609
Planta , IF:4.116 , 2021 Jul , V254 (2) : P28 doi: 10.1007/s00425-021-03678-1
Contribution of strigolactone in plant physiology, hormonal interaction and abiotic stresses.
School of Studies in Biotechnology, Pt. Ravishankar Shukla University, Raipur, 492 010, India.; School of Life and Allied Sciences, ITM University, Raipur, 492 002, India.; School of Studies in Biotechnology, Pt. Ravishankar Shukla University, Raipur, 492 010, India. skeshavkant@gmail.com.; National Center for Natural Resources, Pt. Ravishankar Shukla University, Raipur, 492 010, India. skeshavkant@gmail.com.
Strigolactones (SLs) are carotenoid-derived molecules, which regulate various developmental and adaptation processes in plants. These are engaged in different aspects of growth such as development of root, leaf senescence, shoot branching, etc. Plants grown under nutrient-deficient conditions enhance SL production that facilitates root architecture and symbiosis of arbuscular mycorrhizal fungi, as a result increases nutrient uptake. The crosstalk of SLs with other phytohormones such as auxin, abscisic acid, cytokinin and gibberellins, in response to abiotic stresses indicates that SLs actively contribute to the regulatory systems of plant stress adaptation. In response to different environmental circumstances such as salinity, drought, heat, cold, heavy metals and nutrient deprivation, these SLs get accumulated in plant tissues. Strigolactones regulate multiple hormonal responsive pathways, which aids plants to surmount stressful environmental constraints as well as reduce negative impact on overall productivity of crops. The external application of SL analog GR24 for its higher bioaccumulation can be one of the possible approaches for establishing various abiotic stress tolerances in plants.
PMID: 34241703
Plant Genome , IF:4.089 , 2021 Jul : Pe20126 doi: 10.1002/tpg2.20126
Comparative transcriptomics and network analysis define gene coexpression modules that control maize aleurone development and auxin signaling.
Dep. of Genetics, Development & Cell Biology, IA State Univ., Ames, IA, 50011, USA.; Agronomy Dep., IA State Univ., Ames, IA, 50011, USA.
The naked endosperm1 (nkd1), naked endosperm2 (nkd2), and thick aleurone1 (thk1) genes are important regulators of maize (Zea mays L.) endosperm development. Double mutants of nkd1 and nkd2 (nkd1,2) show multiple aleurone (AL) cell layers with disrupted AL cell differentiation, whereas mutants of thk1 cause multiple cell layers of fully differentiated AL cells. Here, we conducted a comparative analysis of nkd1,2 and thk1 mutant endosperm transcriptomes to study how these factors regulate gene networks to control AL layer specification and cell differentiation. Weighted gene coexpression network analysis was incorporated with published laser capture microdissected transcriptome datasets to identify a coexpression module associated with AL development. In this module, both Nkd1,2+ and Thk1+ appear to regulate cell cycle and division, whereas Nkd1,2+, but not Thk1+, regulate auxin signaling. Further investigation of nkd1,2 differentially expressed genes combined with published putative targets of auxin response factors (ARFs) identified 61 AL-preferential genes that may be directly activated by NKD-modulated ARFs. All 61 genes were upregulated in nkd1,2 mutant and the enriched Gene Ontology terms suggested that they are associated with hormone crosstalk, lipid metabolism, and developmental growth. Expression of a transgenic DR5-red fluorescent protein auxin reporter was significantly higher in nkd1,2 mutant endosperm than in wild type, supporting the prediction that Nkd1,2+ negatively regulate auxin signaling in developing AL. Overall, these results suggest that Nkd1,2+ and Thk1+ may normally restrict AL development to a single cell layer by limiting cell division, and that Nkd1,2+ restrict auxin signaling in the AL to maintain normal cell patterning and differentiation processes.
PMID: 34323399
Plant Mol Biol , IF:4.076 , 2021 Jul doi: 10.1007/s11103-021-01175-3
Transcriptomic analysis provides insights into the AUXIN RESPONSE FACTOR 6-mediated repression of nicotine biosynthesis in tobacco (Nicotiana tabacum L.).
Yunnan Academy of Tobacco Agricultural Sciences, Kunming, 650021, Yunnan, China.; College of Agronomy and Biotechnology, Southwest University, Chongqing, 400715, China.; Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, 266101, Shandong, China.; Yunnan Academy of Tobacco Agricultural Sciences, Kunming, 650021, Yunnan, China. xueyisui2017@hotmail.com.
KEY MESSAGE: NtARF6 overexpression represses nicotine biosynthesis in tobacco. Transcriptome analysis suggests that NtARF6 acts as a regulatory hub that connect different phytohormone signaling pathways to antagonize the jasmonic acid-induced nicotine biosynthesis. Plant specialized metabolic pathways are regulated by a plethora of molecular regulators that form complex networks. In Nicotiana tabacum, nicotine biosynthesis is regulated by transcriptional activators, such as NtMYC2 and the NIC2-locus ERFs. However, the underlying molecular mechanism of the regulatory feedback is largely unknown. Previous research has shown that NbARF1, a nicotine synthesis repressor, reduces nicotine accumulation in N. benthamiana. In this study, we demonstrated that overexpression of NtARF6, an ortholog of NbARF1, was able to reduce pyridine alkaloid accumulation in tobacco. We found that NtARF6 could not directly repress the transcriptional activities of the key nicotine pathway structural gene promoters. Transcriptomic analysis suggested that this NtARF6-induced deactivation of alkaloid biosynthesis might be achieved by the antagonistic effect between jasmonic acid (JA) and other plant hormone signaling pathways, such as ethylene (ETH), salicylic acid (SA), abscisic acid (ABA). The repression of JA biosynthesis is accompanied by the induction of ETH, ABA, and SA signaling and pathogenic infection defensive responses, resulting in counteracting JA-induced metabolic reprogramming and decreasing the expression of nicotine biosynthetic genes in vivo. This study provides transcriptomic evidence for the regulatory mechanism of the NtARF6-mediated repression of alkaloid biosynthesis and indicates that this ARF transcription factor might act as a regulatory hub to connect different hormone signaling pathways in tobacco.
PMID: 34302568
Funct Integr Genomics , IF:3.41 , 2021 Jul , V21 (3-4) : P489-502 doi: 10.1007/s10142-021-00793-w
Combined drought and heat stresses trigger different sets of miRNAs in contrasting potato cultivars.
Ayhan Sahenk Faculty of Agricultural Sciences and Technologies, Department of Agricultural Genetic Engineering, Nigde Omer Halisdemir University, 51240, Nigde, Turkey. zahideneslihan_ozturk@ohu.edu.tr.; Ayhan Sahenk Faculty of Agricultural Sciences and Technologies, Department of Agricultural Genetic Engineering, Nigde Omer Halisdemir University, 51240, Nigde, Turkey.
MicroRNAs are small, non-coding RNAs that are responsible for regulation of gene expression during plant growth and development. Although there are many studies on miRNAs in other plants, little work has been done to understand the role of miRNAs in abiotic stress tolerance in potatoes. This study investigates changes in miRNA profiles of two different potato cultivars (tolerant, Unica and susceptible, Russet Burbank) in response to heat, drought and their combination. Transcriptomic studies revealed that miRNA profiles depend on the susceptibility and tolerance of the cultivar and also the stress conditions. Large number of miRNAs were expressed in Unica, whereas Russet Burbank indicated lesser number of changes in miRNA expression. Physiological and transcriptional results clearly supported that Unica cultivar is tolerant to combined drought and heat stress compared to Russet Burbank. Moreover, psRNATarget analysis predicted that major miRNAs identified were targeting genes playing important roles in response to drought and heat stress and their important roles in genetic and post-transcriptional regulation, root development, auxin responses and embryogenesis were also observed. This study focused on eight miRNAs (Novel_8, Novel_9, Novel_105, miR156d-3p, miR160a-5p, miR162a-3p, miR172b-3p and miR398a-5p) and their putative targets where results indicate that they may play a vital role at different post-transcriptional levels against drought and heat stresses. We suggest that miRNA overexpression in plants can lead to increased tolerance against abiotic stresses; furthermore, there should be more emphasis on the studies to investigate the role of miRNAs in combined abiotic stress in plants.
PMID: 34241734
Protoplasma , IF:3.356 , 2021 Jul doi: 10.1007/s00709-021-01683-5
Forever young: stem cell and plant regeneration one century after Haberlandt 1921.
I-Cultiver, Inc., Treasure Island, San Francisco, CA, 94130, USA. kutscherau@gmail.com.; Department of Biology, Stanford University, Stanford, CA, 94305, USA. kutscherau@gmail.com.; Department of Biology, Stanford University, Stanford, CA, 94305, USA. pray@stanford.edu.; Institute of Arctic Biology, University of Alaska Fairbanks, Anchorage, AL, 99775, USA. pray@stanford.edu.
Plants are characterized by a post-embryonic mode of organ development, which results in a need for these photoautotrophic organisms to regenerate lost parts in the course of their life cycle. This capacity depends on the presence of "pluripotent stem cells," which are part of the meristems within the plant body. One hundred years ago, the botanist Gottlieb Haberlandt (1854-1945) published experiments showing wounding-induced callus formation, which led ultimately to plant regeneration in tissue culture and thence to the techniques of "plant biotechnology," with practical applications for mankind. Here, we recount Haberlandt's discovery within the context of his long research life and his most influential book Physiologische Pflanzenanatomie. In the second part, we describe and analyze a plant tissue-culture regeneration system using sterile, dark-grown sunflower (Helianthus annuus) seedlings as experimental material. We document that excised hook segments, which contain a "stem cell niche," can regenerate entire miniature H. annuus-plantlets that, raised in a light/dark regime, develop flowers. Finally, we discuss molecular data relevant to plant regeneration with reference to phytohormones and conclude that, one century after Haberlandt, 1921, the exact biochemical/genetic mechanisms responsible for the capability of stem cells to remain "forever young" are, although already complex, really just beginning to become known.
PMID: 34292403
PLoS One , IF:3.24 , 2021 , V16 (7) : Pe0249160 doi: 10.1371/journal.pone.0249160
Evaluation of substrate composition and exogenous hormone application on vegetative propagule rooting success of essential oil hemp (Cannabis sativa L.).
Department of Environmental Horticulture, Mid-Florida Research and Education Center, University of Florida, Institute of Food and Agricultural Sciences, Apopka, Florida, United States of America.; Department of Agronomy, Tropical Research and Education Center, University of Florida, Institute of Food and Agricultural Sciences, Homestead, Florida, United States of America.
To support the rapidly expanding industrial hemp industry, a commercial supply of high-quality starter plants with low genetic variability from nurseries will be key to consistent and efficient cultivation efforts. Rooting success was evaluated across four propagation medias, five rooting hormones, and eight commercially available high-cannabidiol (CBD) essential oil hemp cultivars. Cuttings were placed in a climate-controlled room and assessed for rooting success 12 days after cloning. Rooting success was determined by quantifying total root number, cumulative total root length, and total root mass. Propagation media had the greatest effect on rooting success (13-80%). Rockwool had the highest rooting success resulting in 10-fold increases in rooting traits over the next highest scoring medium (Berger BM6). Hormone applications significantly improved (15- to 18-fold) rooting success compared to no hormone application, while non-statistical differences were observed across auxin hormone concentrations and application methods. Genetic variation in rooting response was observed between cultivars with 'Cherry Wine' outperforming all other cultivars with an approximate 20% increase in rooting success over the next highest rooting cultivar, 'Wife'. Although the ideal combination was not specifically identified in this study, findings provide insight into how rooting hormone application and medium selection impact vegetative propagule rooting success of essential oil hemp.
PMID: 34324510
PLoS One , IF:3.24 , 2021 , V16 (7) : Pe0253812 doi: 10.1371/journal.pone.0253812
Effects of graphene on morphology, microstructure and transcriptomic profiling of Pinus tabuliformis Carr. roots.
Key Laboratory of National Forest and Grass Administration for the Application of Graphene in Forestry, Institute of Carbon Materials Science, Shanxi Datong University, Datong, P.R. China.; College of Life Science, Shanxi Datong University, Datong, Shanxi Province, PR China.; College of Chemistry and Chemical Engineering, Shanxi Datong University, Datong, P.R. China.; National Fine Variety Base of Pinus sylvestris var. in Honghuaerji Forestry Bureau, Hulunbeir Inner Mongolia, PR China.; Shanxi Poplar High-yield Forest Bureau, Datong, Shanxi Province, PR China.
Graphene has shown great potential for improving growth of many plants, but its effect on woody plants remains essentially unstudied. In this work, Pinus tabuliformis Carr. bare-rooted seedlings grown outdoors in pots were irrigated with a graphene solution over a concentration range of 0-50 mg/L for six months. Graphene was found to stimulate root growth, with a maximal effect at 25 mg/L. We then investigated root microstructure and carried out transcript profiling of root materials treated with 0 and 25 mg/L graphene. Graphene treatment resulted in plasma-wall separation and destruction of membrane integrity in root cells. More than 50 thousand of differentially expressed genes (DEGs) were obtained by RNA sequencing, among which 6477 could be annotated using other plant databases. The GO enrichment analysis and KEGG pathway analysis of the annotated DEGs indicated that abiotic stress responses, which resemble salt stress, were induced by graphene treatment in roots, while responses to biotic stimuli were inhibited. Numerous metabolic processes and hormone signal transduction pathways were altered by the treatment. The growth promotion effects of graphene may be mediated by encouraging proline synthesis, and suppression of the expression of the auxin response gene SMALL AUXIN UP-REGULATED RNA 41 (SAUR41), PYL genes which encode ABA receptors, and GSK3 homologs.
PMID: 34237067
Plant Signal Behav , IF:2.247 , 2021 Jul , V16 (7) : P1891756 doi: 10.1080/15592324.2021.1891756
Synthesis and regulation of auxin and abscisic acid in maize.
Gansu Provincial Key Laboratory of Aridland Crop Science, Lanzhou, China.; College of Agronomy, Gansu Agricultural University, Lanzhou, China.; Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, USA.; College of Resource and Environment, Gansu Agricultural University, Lanzhou, China.
Indole-3-acetic acid (IAA), the primary auxin in higher plants, and abscisic acid (ABA) play crucial roles in the ability of maize (Zea mays L.) to acclimatize to various environments by mediating growth, development, defense and nutrient allocation. Although understanding the biochemical reactions for IAA and ABA biosynthesis and signal transduction has progressed, the mechanisms by which auxin and ABA are synthesized and transduced in maize have not been fully elucidated to date. The synthesis and signal transduction pathway of IAA and ABA in maize can be analyzed using an existing model. This article focuses on the research progress toward understanding the synthesis and signaling pathways of IAA and ABA, as well as IAA and ABA regulation of maize growth, providing insight for future development and the significance of IAA and ABA for maize improvement.
PMID: 34057034
Plant Signal Behav , IF:2.247 , 2021 Jul , V16 (7) : P1913845 doi: 10.1080/15592324.2021.1913845
Virus-induced gene silencing (VIGS) analysis shows involvement of the LsSTPK gene in lettuce (Lactuca sativaL.) in high temperature-induced bolting.
Beijing Key Laboratory for Agricultural Application and New Technology, National Demonstration Center for Experimental Plant Production Education, College of Plant Science and Technology, Beijing University of Agriculture, Beijing, China.; University of Arizona, Tucson, Arizona, USA.
To determine the effect of the serine/threonine protein kinase (STPK) gene on leaf lettuce bolting, we utilized virus-induced gene silencing (VIGS) using the TRV vector to silence the target gene. The 'GB30' leaf lettuce cultivar was the test material, and the methods included gene cloning, bioinformatics analysis, quantitative real-time PCR (qRT-PCR) and VIGS. LsSTPK, was cloned from the 'GB30' leaf lettuce cultivar via reverse transcription-polymerase chain reaction (RT-PCR). qRT-PCR analysis showed that the expression of LsSTPK in the stem of leaf lettuce was significantly greater than that in the roots and leaves, and after high-temperature treatment, the gene expression in the stems in the experimental group was markedly lower than that in the control groups. Following LsSTPK silencing via the VIGS method, the stem length in the treatment group was significantly greater than that in the blank and negative control groups, and the contents of auxin (IAA), GA3 and abscisic acid (ABA) in the treatment group were greater than those in the other two groups. Flower bud differentiation occurred in the treatment group but not in the control group. The above findings suggested that LsSTPK inhibits the bolting of leaf lettuce under high-temperature conditions.
PMID: 33955335