Nat Commun , IF:12.121 , 2020 Jul , V11 (1) : P3508 doi: 10.1038/s41467-020-17252-y
Strigolactones inhibit auxin feedback on PIN-dependent auxin transport canalization.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China. zhangj@cau.edu.cn.; University of Silesia in Katowice, Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, Jagiellonska 28, 40-032, Katowice, Poland.; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), 62500, Brno, Czech Republic.; Central European Institute of Technology (CEITEC), Mendel University in Brno, Zemedelska 1, 61300, Brno, Czech Republic.; Department of Plant Biology, Mendel University in Brno, Zemedelska 1, 61300, Brno, Czech Republic.; Institute of Science and Technology (IST), Klosterneuburg, 3400, Austria.; State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.; Central Laboratories and Research Support, Centre of the Region Hana for Biotechnological and Agricultural Research, Palacky University, Slechtitelu 27, 78371, Olomouc, Czech Republic.; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Muthgasse 18, 1190, Wien, Austria.; ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Precinct, The University of Adelaide, Glen Osmond, SA, 5064, Australia.; Institute of Science and Technology (IST), Klosterneuburg, 3400, Austria. jiri.friml@ist.ac.at.
Directional transport of the phytohormone auxin is a versatile, plant-specific mechanism regulating many aspects of plant development. The recently identified plant hormones, strigolactones (SLs), are implicated in many plant traits; among others, they modify the phenotypic output of PIN-FORMED (PIN) auxin transporters for fine-tuning of growth and developmental responses. Here, we show in pea and Arabidopsis that SLs target processes dependent on the canalization of auxin flow, which involves auxin feedback on PIN subcellular distribution. D14 receptor- and MAX2 F-box-mediated SL signaling inhibits the formation of auxin-conducting channels after wounding or from artificial auxin sources, during vasculature de novo formation and regeneration. At the cellular level, SLs interfere with auxin effects on PIN polar targeting, constitutive PIN trafficking as well as clathrin-mediated endocytosis. Our results identify a non-transcriptional mechanism of SL action, uncoupling auxin feedback on PIN polarity and trafficking, thereby regulating vascular tissue formation and regeneration.
PMID: 32665554
Dev Cell , IF:10.092 , 2020 Jul , V54 (2) : P171-182 doi: 10.1016/j.devcel.2020.05.005
Metabolic Cellular Communications: Feedback Mechanisms between Membrane Lipid Homeostasis and Plant Development.
UMR 5200 Membrane Biogenesis Laboratory, CNRS, University of Bordeaux, Batiment A3 - INRAE Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux CS 20032, 33140 Villenave d'Ornon, France. Electronic address: yohann.boutte@u-bordeaux.fr.; Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, 69342 Lyon, France. Electronic address: yvon.jaillais@ens-lyon.fr.
Membrane lipids are often viewed as passive building blocks of the endomembrane system. However, mounting evidence suggests that sphingolipids, sterols, and phospholipids are specifically targeted by developmental pathways, notably hormones, in a cell- or tissue-specific manner to regulate plant growth and development. Targeted modifications of lipid homeostasis may act as a way to execute a defined developmental program, for example, by regulating other signaling pathways or participating in cell differentiation. Furthermore, these regulations often feed back on the very signaling pathway that initiates the lipid metabolic changes. Here, we review several recent examples highlighting the intricate feedbacks between membrane lipid homeostasis and plant development. In particular, these examples illustrate how all aspects of membrane lipid metabolic pathways are targeted by these feedback regulations. We propose that the time has come to consider membrane lipids and lipid metabolism as an integral part of the developmental program needed to build a plant.
PMID: 32502395
EMBO J , IF:9.889 , 2020 Jul : Pe104238 doi: 10.15252/embj.2019104238
Phytohormone cytokinin guides microtubule dynamics during cell progression from proliferative to differentiated stage.
Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria.; Department of Plant Biotechnology and Bioinformatics, Ghent University and Center for Plant Systems Biology, VIB, Gent, Belgium.; Bioresources Unit, Center for Health & Bioresources, AIT Austrian Institute of Technology GmbH, Tulln, Austria.; Institute of Experimental Botany, The Czech Academy of Sciences, Praha, Czech Republic.
Cell production and differentiation for the acquisition of specific functions are key features of living systems. The dynamic network of cellular microtubules provides the necessary platform to accommodate processes associated with the transition of cells through the individual phases of cytogenesis. Here, we show that the plant hormone cytokinin fine-tunes the activity of the microtubular cytoskeleton during cell differentiation and counteracts microtubular rearrangements driven by the hormone auxin. The endogenous upward gradient of cytokinin activity along the longitudinal growth axis in Arabidopsis thaliana roots correlates with robust rearrangements of the microtubule cytoskeleton in epidermal cells progressing from the proliferative to the differentiation stage. Controlled increases in cytokinin activity result in premature re-organization of the microtubule network from transversal to an oblique disposition in cells prior to their differentiation, whereas attenuated hormone perception delays cytoskeleton conversion into a configuration typical for differentiated cells. Intriguingly, cytokinin can interfere with microtubules also in animal cells, such as leukocytes, suggesting that a cytokinin-sensitive control pathway for the microtubular cytoskeleton may be at least partially conserved between plant and animal cells.
PMID: 32667089
Plant Cell , IF:9.618 , 2020 Jul doi: 10.1105/tpc.20.00126
Regulation of Female Germline Specification via Small RNA Mobility in Arabidopsis.
Shenzhen University CITY: Shenzhen China [CN].; Fujian Agriculture and Forestry University CITY: Fuzhou STATE: Fujian China [CN].; State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops; Ministry of Education; Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Center for Genomics and Biotechnology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian Province, China CITY: fuzhou China [CN].; Fujian Agriculture and Forestry University CITY: Fuzhou China [CN].; University of California, Riverside CITY: Riverside STATE: California POSTAL_CODE: 92521 United States Of America [US] xuemei.chen@ucr.edu.
In the ovules of most sexually reproducing plants, one hypodermal cell differentiates into a megaspore mother cell (MMC), which gives rise to the female germline. Trans-acting small interfering RNAs known as tasiR-ARFs have been suggested to act non-cell autonomously to prevent the formation of multiple MMCs by repressing AUXIN RESPONSE FACTOR3 (ARF3) expression in Arabidopsis thaliana, but the underlying mechanisms are unknown. Here, we examined tasiR-ARF-related intercellular regulatory mechanisms. Expression analysis revealed that components of the tasiR-ARF biogenesis pathway are restricted to distinct ovule cell types, thus limiting tasiR-ARF production to the nucellar epidermis. We also provide data suggesting tasiR-ARF movement along the medio-lateral axis into the hypodermal cell and basipetally into the chalaza. Furthermore, we used cell type-specific promoters to express ARF3m, which is resistant to tasiR-ARF regulation, in different ovule cell layers. ARF3m expression in hypodermal cells surrounding the MMC, but not in epidermal cells, led to a multiple-MMC phenotype, suggesting that tasiR-ARFs repress ARF3 in these hypodermal cells to suppress ectopic MMC fate. RNA-seq analyses in plants with hypodermally expressed ARF3m showed that ARF3 potentially regulates MMC specification through phytohormone pathways. Our findings uncover intricate spatial restriction of tasiR-ARF biogenesis, which together with tasiR-ARF mobility, enables cell-cell communication in MMC differentiation.
PMID: 32703817
Plant Cell , IF:9.618 , 2020 Jul doi: 10.1105/tpc.20.00512
Peptide-Receptor Signaling Pumps the Brakes on Auxin Biosynthesis and Ethylene Signaling to Haromonize Root Growth and Nodulation.
Cornell University CITY: Ithaca STATE: NY United States Of America [US] jjs369@cornell.edu.
PMID: 32641347
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Jul , V117 (28) : P16667-16677 doi: 10.1073/pnas.2006620117
Rocks in the auxin stream: Wound-induced auxin accumulation and ERF115 expression synergistically drive stem cell regeneration.
Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium.; Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium.; Department for Systems Biology, Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia.; LCT & EB, Novosibirsk State University, 630090 Novosibirsk, Russia.; Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore.; Integrated Molecular Plant Physiology Research, Department of Biology, University of Antwerp, 2020 Antwerp, Belgium.; Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 7612001, Israel.; Department of Plant Systems Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, 6525 AJ Nijmegen, The Netherlands.; Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium; lieven.deveylder@psb.vib-ugent.be.
Plants are known for their outstanding capacity to recover from various wounds and injuries. However, it remains largely unknown how plants sense diverse forms of injury and canalize existing developmental processes into the execution of a correct regenerative response. Auxin, a cardinal plant hormone with morphogen-like properties, has been previously implicated in the recovery from diverse types of wounding and organ loss. Here, through a combination of cellular imaging and in silico modeling, we demonstrate that vascular stem cell death obstructs the polar auxin flux, much alike rocks in a stream, and causes it to accumulate in the endodermis. This in turn grants the endodermal cells the capacity to undergo periclinal cell division to repopulate the vascular stem cell pool. Replenishment of the vasculature by the endodermis depends on the transcription factor ERF115, a wound-inducible regulator of stem cell division. Although not the primary inducer, auxin is required to maintain ERF115 expression. Conversely, ERF115 sensitizes cells to auxin by activating ARF5/MONOPTEROS, an auxin-responsive transcription factor involved in the global auxin response, tissue patterning, and organ formation. Together, the wound-induced auxin accumulation and ERF115 expression grant the endodermal cells stem cell activity. Our work provides a mechanistic model for wound-induced stem cell regeneration in which ERF115 acts as a wound-inducible stem cell organizer that interprets wound-induced auxin maxima.
PMID: 32601177
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Jul , V117 (27) : P16027-16034 doi: 10.1073/pnas.2007400117
Fluctuating auxin response gradients determine pavement cell-shape acquisition.
Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden.; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium.; VIB Center for Plant Systems Biology, Ghent University, 9052 Ghent, Belgium.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden; stephanie.robert@slu.se.
Puzzle-shaped pavement cells provide a powerful model system to investigate the cellular and subcellular processes underlying complex cell-shape determination in plants. To better understand pavement cell-shape acquisition and the role of auxin in this process, we focused on the spirals of young stomatal lineage ground cells of Arabidopsis leaf epidermis. The predictability of lobe formation in these cells allowed us to demonstrate that the auxin response gradient forms within the cells of the spiral and fluctuates based on the particular stage of lobe development. We revealed that specific localization of auxin transporters at the different membranes of these young cells changes during the course of lobe formation, suggesting that these fluctuating auxin response gradients are orchestrated via auxin transport to control lobe formation and determine pavement cell shape.
PMID: 32571946
New Phytol , IF:8.512 , 2020 Jul doi: 10.1111/nph.16828
A basic/helix-loop-helix transcription factor controls leaf shape by regulating auxin signaling in apple.
State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China.; State Key Laboratory of Crop Biology, State Forestry and Grassland Administration Key Laboratory of Silviculture in downstream areas of the Yellow River, College of Forestry, Shandong Agricultural University, Tai'an, Shandong, 271018, China.; State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, 100871, China.; Department of Horticulture, Cornell University, 134A Plant Science, Ithaca, NY, 14853, USA.; College of Agricultural Sciences, Gansu Agricultural University, Lanzhou, 730000, China.
Climate-driven phenological change across local spatial gradients leads to leaf shape variation. At higher elevations, leaves of broad-leaf species tend to become narrower, but the underlying molecular mechanism is largely unknown. Here, a series of morphometric analyses and biochemical assays, combined with functional identification in apple were performed in this study. We show that the decrease in apple leaf width with increasing altitude is controlled by a basic/helix-loop-helix transcription factor (bHLH TF), MdbHLH3. The MdbHLH3-overexpressing lines have a lower transcript level of MdPIN1 encoding an auxin efflux carrier but a higher transcript level of MdGH3-2 encoding a putative auxin amido conjugate synthase, resulting in a lower free auxin level; feeding the transgenic leaves with exogenous auxin partially restores leaf width. MdbHLH3 transcriptionally suppresses and activates MdPIN1 and MdGH3-2, respectively, by specifically binding to their promoters. This alters auxin homeostasis and transport, consequently leading to changes in leaf shape. These findings suggest that the bHLH TF MdbHLH3 directly modulates auxin signaling in controlling leaf shape in response to local spatial gradients in apple.
PMID: 32712992
Plant Biotechnol J , IF:8.154 , 2020 Jul doi: 10.1111/pbi.13448
R2R3 MYB-dependent auxin signalling regulates trichome formation, and increased trichome density confers spider mite tolerance on tomato.
Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing, China.; Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, China.; Department of Plant Sciences, University of California, Davis, CA, USA.; College of Agriculture, Guangxi University, Nanning, China.; Crops Pathology and Genetics Research Unit, United States Department of Agriculture, Agricultural Research Service, Davis, CA, USA.
Unicellular and multicellular tomato trichomes function as mechanical and chemical barriers against herbivores. Auxin treatment increased the formation of II, V and VI type trichomes in tomato leaves. The auxin response factor gene SlARF4, which was highly expressed in II, V and VI type trichomes, positively regulated the auxin-induced formation of II, V and VI type trichomes in the tomato leaves. SlARF4 overexpression plants with high densities of these trichomes exhibited tolerance to spider mites. Two R2R3 MYB genes, SlTHM1 and SlMYB52, were directly targeted and inhibited by SlARF4. SlTHM1 was specifically expressed in II and VI type trichomes and negatively regulated the auxin-induced formation of II and VI type trichomes in the tomato leaves. SlTHM1 down-regulation plants with high densities of II and VI type trichomes also showed tolerance to spider mites. SlMYB52 was specifically expressed in V type trichomes and negatively regulated the auxin-induced formation of V type trichome in the tomato leaves. The regulation of SlARF4 on the formation of II, V and VI type trichomes depended on SlTHM1 and SlMYB52, which directly targeted cyclin gene SlCycB2 and increased its expression. In conclusion, our data indicates that the R2R3 MYB-dependent auxin signalling pathway regulates the formation of II, V and VI type trichomes in tomato leaves. Our study provides an effective method for improving the tolerance of tomato to spider mites.
PMID: 32654333
Plant Biotechnol J , IF:8.154 , 2020 Jul doi: 10.1111/pbi.13440
TAC4 controls tiller angle by regulating the endogenous auxin content and distribution in rice.
State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing, China.; National Center for Evaluation of Agricultural Wild Plants (Rice), Beijing Key Laboratory of Crop Genetic Improvement, Laboratory of Crop Heterosis and Utilization, MOE, Department of Plant Genetics and Breeding, China Agricultural University, Beijing, China.
Tiller angle, an important component of plant architecture, greatly influences the grain yield of rice (Oryza sativa L.). Here, we identified Tiller Angle Control 4 (TAC4) as a novel regulator of rice tiller angle. TAC4 encodes a plant-specific, highly conserved nuclear protein. The loss of TAC4 function leads to a significant increase in the tiller angle. TAC4 can regulate rice shoot gravitropism by increasing the indole acetic acid content and affecting the auxin distribution. A sequence analysis revealed that TAC4 has undergone a bottleneck and become fixed in indica cultivars during domestication and improvement. Our findings facilitate an increased understanding of the regulatory mechanisms of tiller angle and also provide a potential gene resource for the improvement of rice plant architecture.
PMID: 32628357
Plant Physiol , IF:6.902 , 2020 Jul doi: 10.1104/pp.19.01250
SAUR15 promotes lateral and adventitious root development via activating H+-ATPases and auxin biosynthesis1.
State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University CITY: Lanzhou STATE: Gansu China [CN].; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University CITY: Lanzhou STATE: Gansu China [CN].; Carleton University CITY: Ottawa STATE: Ontario POSTAL_CODE: K1S5B6 Canada [CA].; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University CITY: Lanzhou STATE: Gansu POSTAL_CODE: 730000 China [CN].; Lanzhou University CITY: LANZHOU POSTAL_CODE: 730000 China [CN] smwang@lzu.edu.cn.
SMALL AUXIN-UP RNAs (SAURs) comprise the largest family of early auxin response genes. Some SAURs have been reported to play important roles in plant growth and development, but their functional relationships with auxin signaling remain unestablished. Here, we report Arabidopsis (Arabidopsis thaliana) SAUR15 acts downstream of the auxin response factors ARF6, 8 and ARF7, 19 to regulate auxin signaling-mediated lateral root (LR) and adventitious root (AR) formation. The loss of function mutant saur15-1 exhibits fewer LRs and ARs. By contrast, plants overexpressing SAUR15 exhibit more LRs and ARs. We find that the SAUR15 promoter contains four tandem auxin-responsive elements, which are directly bound by ARF6 and ARF7 and are essential for SAUR15 expression. LR and AR impairment in arf6 and arf7 mutants is partially reduced by ectopic expression of SAUR15. Additionally, we demonstrate that the ARF6, 7-upregulated SAUR15 promotes LR and AR development using two mechanisms. On the one hand, SAUR15 interacts with PP2C-D subfamily type 2C protein phosphatases to inhibit their activities, thereby stimulating plasma membrane (PM) H+-ATPases, which drives cell expansion and facilitates LR and AR formation. On the other hand, SAUR15 promotes auxin accumulation, potentially by inducing the expression of auxin biosynthesis genes. A resulting increase in free auxin concentration likely triggers LR and AR formation, forming a feedback loop. Our study provides insights and a better understanding of how SAURs function at the molecular level in regulating auxin-mediated LR and AR development.
PMID: 32651188
Sci Total Environ , IF:6.551 , 2020 Jul , V745 : P141032 doi: 10.1016/j.scitotenv.2020.141032
Enhancing the CO2 capturing ability in leaf via xenobiotic auxin uptake.
Faculty of Science and Technology, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland; Charles University in Prague, Faculty of Pharmacy in Hradec Kralove, Heyrovskeho 1203, Hradec Kralove 500 05, Czech Republic.; Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Jagiellonska 28, 40-032 Katowice, Poland.; Faculty of Science and Technology, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland.; Faculty of Science and Technology, August Chelkowski Institute of Physics, University of Silesia in Katowice, Bankowa 14, 40-007 Katowice, Poland.; Charles University in Prague, Faculty of Pharmacy in Hradec Kralove, Heyrovskeho 1203, Hradec Kralove 500 05, Czech Republic.; Faculty of Science and Technology, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland. Electronic address: polanski@us.edu.pl.
Plants are masterpieces of evolution that is based on carbon chemistry. In particular, plant leaves are biosynthetic factories able to convert CO2 into carbohydrates and oxygen. It is worth noting that mimicking the efficiency of a natural plant and natural leaf is still a challenge for contemporary chemistry. We can even better realize this when we notice that a plant and an industrial factory are equivalent in meaning. On the other hand, green technologies are under development in a quest for the artificial leaf. If we could modify the synthetic pathways in leaves, we could also design green chemistry schemes in natural leaves to produce useful chemicals or to digest wastes or toxins. Specifically, can we intensify the potential for capturing atmospheric CO2 in leaves? Auxins are plant hormones that control the growth and development of plants. Herein, we determined whether we could efficiently transport xenobiotic auxin into leaves and if so, whether this supply could enhance the metabolism and CO2 capturing ability. By exploring a series of dioxolanes as potential enhancers of auxin transport, we discovered for the first time that a small molecular compound, 2,2-dimethyl-1,3-dioxolane (DMD), enhances the xenobiotic auxin transport to leaves, which boosts the metabolism that is measured by H2O2 production as well as CO2 capturing ability in leaves.
PMID: 32726691
Genomics , IF:6.205 , 2020 Jul doi: 10.1016/j.ygeno.2020.07.029
Genome-wide identification and expression analysis of extensin genes in tomato.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.; Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, China.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China; Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: wuhan@njau.edu.cn.
Extensins (EXTs) are major protein components in plant cell walls that play crucial roles in higher plants. The function of EXTs has been reported in several plants but is limited in tomato, especially in fruit ripening. In this study, we identified 83 EXTs in tomato, and divided them into seven groups. The gene intron-exon structure and protein-motif composition of SlEXTs were similar within each group but different among groups. SlEXT genes showed different expression patterns in roots, leaves, flowers and fruits, and some SlEXT gene expressions in flowers could be regulated by treatments of auxin, gibberellic acid and jasmonic acid. In particular, SlSEXT8 had higher and increased expression during tomato fruit ripening, and its expression could be induced by ethylene, suggesting SlSEXT8 may be involved in tomato fruit softening. The result provides insights into the function of EXTs, and will facilitate to further study EXT roles in tomato fruit ripening.
PMID: 32712296
Genomics , IF:6.205 , 2020 Jul doi: 10.1016/j.ygeno.2020.07.022
Comparative transcriptomic analysis reveals that multiple hormone signal transduction and carbohydrate metabolic pathways are affected by Bacillus cereus in Nicotiana tabacum.
State Key Laboratory of Silkworm Genome Biology, Biological Science Research Center, Southwest University, Chongqing 400716, China.; Chongqing Institute of Tobacco Science, Chongqing 400716, China.; Technology Center of China, Tobacco Chongqing Industrial Co.,Ltd, Chongqing 400000, China.; China Tobacco Gene Research Center, Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou 450001, China.; State Key Laboratory of Silkworm Genome Biology, Biological Science Research Center, Southwest University, Chongqing 400716, China. Electronic address: wanggh168@swu.edu.cn.
Bacillus cereus is thought to be a beneficial bacterium for plants in several aspects, such as promoting plant growth and inducing plant disease resistance. However, there is no detailed report on the effect of Bacillus cereus acting on Nicotiana tabacum. In the present study, RNA-based sequencing (RNAseq) was used to identify the molecular mechanisms of the interaction between B. cereus CGMCC 5977 and N. tabacum. A total of 7345 and 5604 differentially expressed genes (DEGs) were identified from leaves inoculated with Bacillus cereus at 6 and 24 hpi, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that the most DEGs could be significantly enriched in hormone signal transduction, the MAPK signaling pathway, photosynthesis, oxidative stress, and amino sugar, and nucleotide sugar metabolism. Furthermore, glycolysis/gluconeogenesis was severely affected by inoculation with Bacillus cereus. In the hormone signal pathway, multiple DEGs were involved in plant defense-related major hormones, including activation of jasmonic acid (JA), salicylic acid (SA), and ethylene (Eth). Further analyses showed that other hormone-related genes involved in abscisic acid (ABA), gibberellin (GA), auxin (AUX), and cytokinin (CK) also showed changes. Notably, a large number of genes associated with glycolysis/gluconeogenesis, catabolism of starch and oxidative stress were induced. In addition, the majority of DEGs related to nucleic acid sugar metabolism were also significantly upregulated. Biochemical assays showed that the starch content of B. cereus-treated leaves was reduced to 2.51mg/g and 2.38mg/g at 6 and 24 hpi, respectively, while that of the control sample was 5.42mg/g. Overall, our results demonstrated that multiple hormone signal transduction and carbohydrate metabolic pathways are involved in the interaction of tobacco and B. cereus.
PMID: 32679071
Genomics , IF:6.205 , 2020 Jul doi: 10.1016/j.ygeno.2020.07.005
Comparative transcriptome and metabolomic profiling reveal the complex mechanisms underlying the developmental dynamics of tobacco leaves.
College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China.; Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China; Upland Flue-Cured Tobacco Quality and Ecology Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China.; College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China; Academy of Agricultural Sciences, Southwest University, Chongqing 400715, China; Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing 400715, China.; Molecular Genetics Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China; Upland Flue-Cured Tobacco Quality and Ecology Key Laboratory of China Tobacco, Guizhou Academy of Tobacco Science, Guiyang 550081, China; College of Life Sciences, Yangtze University, Jingzhou 434025, Hubei, China. Electronic address: leibo_1981@163.com.; College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China; Academy of Agricultural Sciences, Southwest University, Chongqing 400715, China; Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing 400715, China; College of Life Sciences, Yangtze University, Jingzhou 434025, Hubei, China. Electronic address: drlukun@swu.edu.cn.
Although the leaf is the most important photosynthetic organ in most plants, many of the molecular mechanisms underlying leaf developmental dynamics remain to be explored. To better understand the transcriptional regulatory mechanisms involved in leaf development, we conducted comparative transcriptomic and metabolomic analysis of leaves from seven positions on tobacco (Nicotiana tabacum) plants. A total of 35,622 unique differentially expressed genes and 79 metabolites were identified. A time-series expression analysis detected two interesting transcriptional profiles, one comprising 10,197 genes that displayed continual up-regulation during leaf development and another comprising 4696 genes that displayed continual down-regulation. Combining these data with co-expression network results identified four important regulatory networks involved in photorespiration and the tricarboxylic acid cycle; these networks may regulate carbon/nitrogen balance during leaf development. We also found that the transcription factor NtGATA5 acts as a hub associated with C and N metabolism and chloroplast development during leaf development through regulation of phytohormones. Furthermore, we investigated the transcriptional dynamics of genes involved in the auxin, cytokinin, and jasmonic acid biosynthesis and signaling pathways during tobacco leaf development. Overall, our study greatly expands the understanding of the regulatory network controlling developmental dynamics in plant leaves.
PMID: 32650092
Plant J , IF:6.141 , 2020 Jul doi: 10.1111/tpj.14922
ZmDREB2A regulates ZmGH3.2 and ZmRAFS, shifting metabolism towards seed aging tolerance over seedling growth.
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.; The Key Laboratory of Biology and Genetic Improvement of Maize in Arid Areas of the Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China.; The Biology Teaching and Research Core Facility, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China.; Department of Horticulture, Seed Biology Group, College of Agriculture, Food, and Environment, University of Kentucky, Lexington, KY, 40546, USA.; Center of Seed Science and Technology, Beijing Key Laboratory of Crop Genetics and Breeding, Innovation Center for Seed Technology (Ministry of Agriculture), China Agricultural University, Beijing, 100094, China.
Seed aging tolerance and rapid seedling growth are important agronomic traits for crop production; however, how these traits are controlled at the molecular level remains largely unknown. The unaged seeds of two independent maize DEHYDRATION-RESPONSIVE ELEMENT-BINDING2A mutant (zmdreb2a) lines, with decreased expression of GRETCHEN HAGEN3.2 (ZmGH3.2, encoding indole-3-acetic acid [IAA] deactivating enzyme), and increased IAA in their embryo, produced longer seedling shoots and roots, than the null segregant (NS) controls. However, the zmdreb2a seeds, with decreased expression of RAFFINOSE SYNTHASE (ZmRAFS) and less raffinose in their embryo, exhibit decreased seed aging tolerance, than the NS controls. Overexpression of ZmDREB2A in maize protoplasts increased the expression of ZmGH3.2, ZmRAFS genes and that of a Rennila LUCIFERASE reporter (Rluc) gene, which was controlled by either the ZmGH3.2- or ZmRAFS-promoter. Electrophoretic mobility shift assays and chromatin immunoprecipitation assay quantitative polymerase chain reaction showed that ZmDREB2A directly binds to the DRE motif of the promoters of both ZmGH3.2 and ZmRAFS. Exogenous supplementation of IAA to the unaged, germinating NS seeds increased subsequent seedling growth making them similar to the zmdreb2a seedlings from unaged seeds. These findings provide evidence that ZmDREB2A regulates the longevity of maize seed by stimulating the production of raffinose while simultaneously acting to limit auxin-mediated cell expansion.
PMID: 32662115
Anal Chim Acta , IF:5.977 , 2020 Jul , V1120 : P59-66 doi: 10.1016/j.aca.2020.04.051
Digitalized pencil trace modified electrodes for real time evaluation of salicylic acid in detached Arabidopsis thaliana leaves during regeneration.
School of Public Health, Nantong University, Nantong, Jiangsu, 226019, China.; South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou, 510650, China.; School of Life Sciences, Nantong University, Nantong, Jiangsu, 226019, China. Electronic address: slj.1226@163.com.; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China. Electronic address: liuwu@sibs.ac.cn.; School of Public Health, Nantong University, Nantong, Jiangsu, 226019, China. Electronic address: ningbao@ntu.edu.cn.
Plants have excellent abilities to regenerate from detached tissues, in which various phytohormones play critical roles. It has been reported that jasmonate and auxin appeared sequentially during direct de novo root regeneration (DNRR) after leave detachment. However, the role of salicylic acid (SA) is still unknown in this procedure although it is another important plant hormone. We have demonstrated the potential of electrochemical sensors for real time screening of SA but the stability still needed to be improved. Herein a digital plotter was used to modify the carbon tape modified electrodes with pencil traces in order to improve the reproducibility. The modified electrodes in paper-based analytical devices were applied to monitor SA during direct DNRR. The drawing routines and the distances between two close traces were optimized. Our results showed that the carbon tape modified electrodes achieved more reproducible responses of SA. Combined with in vivo sampling, the results using our approach demonstrated that amounts of SA in the wild Arabidopsis thaliana leaves during direct DNRR reached highest at around 72 h after detachment and then decreased, implying that the wave of SA contents might follow that of auxin during direct DNRR. The application of the digital plotter offered a cost-effective and more reproducible method for preparation of disposable working electrodes, which might be extended for other biochemical assays.
PMID: 32475392
J Exp Bot , IF:5.908 , 2020 Jul doi: 10.1093/jxb/eraa321
N-glycosylation is involved in stomatal development partially by modulating the release of active abscisic acid and auxin by beta-glucosidase in Arabidopsis thaliana.
State Key Laboratory of Pharmaceutical Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, Nanjing, China.
Asparagine-linked glycosylation (N-glycosylation) is one of the most important protein modifications in eukaryotes, affecting the folding, transport, and function of a wide range of proteins. However, it is still less known about the roles of N-glycosylation in the development of stomata in plants. In the present study, we provided evidence that the stt3a-2 mutant, defective in oligosaccharyltransferase (OST) catalytic subunit STT3, had a greater transpirational water loss and weaker drought avoidance, accompanied by aberrant stomatal distribution. Through physiological, biochemical, and genetic analyses, we found that the abnormal stomatal density of stt3a-2 was partially attributed to a low endogenous abscisic acid (ABA) and auxin (IAA) content. Exogenous application of ABA or IAA could partially rescue the mutant salt-sensitive and abnormal stomatal phenotype. Further analyses revealed that the decrease of IAA or ABA in stt3a-2 seedlings was associated with the under-glycosylation of beta-glucosidase (AtBG1), catalyzing the conversion of conjugated ABA/IAA to active hormones. Our results provide strong evidence that N-glycosylation is involved in stomatal development and participates in abiotic stress tolerance by affecting the release of active plant hormones.
PMID: 32649744
J Exp Bot , IF:5.908 , 2020 Jul , V71 (15) : P4480-4494 doi: 10.1093/jxb/eraa242
The Arabidopsis NRT1.1 transceptor coordinately controls auxin biosynthesis and transport to regulate root branching in response to nitrate.
BPMP, Univ Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France.; Institute of Science and Technology Austria, Klosterneuburg, Austria.
In agricultural systems, nitrate is the main source of nitrogen available for plants. Besides its role as a nutrient, nitrate has been shown to act as a signal molecule in plant growth, development, and stress responses. In Arabidopsis, the NRT1.1 nitrate transceptor represses lateral root (LR) development at low nitrate availability by promoting auxin basipetal transport out of the LR primordia (LRPs). Here we show that NRT1.1 acts as a negative regulator of the TAR2 auxin biosynthetic gene in the root stele. This is expected to repress local auxin biosynthesis and thus to reduce acropetal auxin supply to the LRPs. Moreover, NRT1.1 also negatively affects expression of the LAX3 auxin influx carrier, thus preventing the cell wall remodeling required for overlying tissue separation during LRP emergence. NRT1.1-mediated repression of both TAR2 and LAX3 is suppressed at high nitrate availability, resulting in nitrate induction of the TAR2 and LAX3 expression that is required for optimal stimulation of LR development by nitrate. Altogether, our results indicate that the NRT1.1 transceptor coordinately controls several crucial auxin-associated processes required for LRP development, and as a consequence that NRT1.1 plays a much more integrated role than previously expected in regulating the nitrate response of root system architecture.
PMID: 32428238
J Exp Bot , IF:5.908 , 2020 Jul , V71 (15) : P4415-4427 doi: 10.1093/jxb/eraa187
How does nitrogen shape plant architecture?
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China.; China MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing, China.
Plant nitrogen (N), acquired mainly in the form of nitrate and ammonium from soil, dominates growth and development, and high-yield crop production relies heavily on N fertilization. The mechanisms of root adaptation to altered supply of N forms and concentrations have been well characterized and reviewed, while reports concerning the effects of N on the architecture of vegetative and reproductive organs are limited and are widely dispersed in the literature. In this review, we summarize the nitrate and amino acid regulation of shoot branching, flowering, and panicle development, as well as the N regulation of cell division and expansion in shaping plant architecture, mainly in cereal crops. The basic regulatory steps involving the control of plant architecture by the N supply are auxin-, cytokinin-, and strigolactone-controlled cell division in shoot apical meristem and gibberellin-controlled inverse regulation of shoot height and tillering. In addition, transport of amino acids has been shown to be involved in the control of shoot branching. The N supply may alter the timing and duration of the transition from the vegetative to the reproductive growth phase, which in turn may affect cereal crop architecture, particularly the structure of panicles for grain yield. Thus, proper manipulation of N-regulated architecture can increase crop yield and N use efficiency.
PMID: 32279073
J Exp Bot , IF:5.908 , 2020 Jul , V71 (14) : P4285-4297 doi: 10.1093/jxb/eraa173
Arabidopsis thaliana trehalose-6-phosphate phosphatase gene TPPI enhances drought tolerance by regulating stomatal apertures.
Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.; College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu, China.; National Engineering Research Center of Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, China.
Transpiration occurs through stomata. The alteration of stomatal apertures in response to drought stress is an important process associated with water use efficiency (WUE). Trehalose-6-phosphate phosphatase (TPP) family genes have been reported to participate in adjustment of stomatal aperture. However, there have been no reports of the trehalose metabolism pathway genes improving WUE, and the upstream signalling pathway modulating these genes is not clear. Here, we demonstrate that a member of the TPP gene family, AtTPPI, confers drought resistance and improves WUE by decreasing stomatal apertures and improving root architecture. The reduced expression of AtTPPI caused a drought-sensitive phenotype, while its overexpression significantly increased drought tolerance. Abscisic acid (ABA)-induced stomatal closure experiments confirmed that AtTPPI mutation increased the stomatal aperture compared with that of wild-type plants; in contrast, overexpression plants had smaller stomatal apertures than those of wild-type plants. Moreover, AtTPPI mutation also caused stunted primary root length and compromised auxin transport, while overexpression plants had longer primary root lengths. Yeast one-hybrid assays showed that ABA-responsive element-binding factor1 (ABF1), ABF2, and ABF4 directly regulated AtTPPI expression. In summary, the way in which AtTPPI responds to drought stress suggests that AtTPPI-mediated stomatal regulation is an important mechanism to cope with drought stress and improve WUE.
PMID: 32242234
J Exp Bot , IF:5.908 , 2020 Jul , V71 (15) : P4512-4530 doi: 10.1093/jxb/eraa130
Seasonal nitrogen remobilization and the role of auxin transport in poplar trees.
Department of Plant Science and Landscape Architecture, University of Maryland, College Park, USA.; OARDC Metabolite Analysis Center, Department of Horticulture and Crop Science, The Ohio State University, Wooster, USA.; Department of Environmental Science and Technology, University of Maryland, College Park, USA.; College of Forestry, Agriculture and Natural Resources, University of Arkansas at Monticello, Monticello, USA.; Department of Radiology, Washington University in St. Louis, St. Louis, USA.
Seasonal nitrogen (N) cycling in Populus, involves bark storage proteins (BSPs) that accumulate in bark phloem parenchyma in the autumn and decline when shoot growth resumes in the spring. Little is known about the contribution of BSPs to growth or the signals regulating N remobilization from BSPs. Knockdown of BSP accumulation via RNAi and N sink manipulations were used to understand how BSP storage influences shoot growth. Reduced accumulation of BSPs delayed bud break and reduced shoot growth following dormancy. Further, 13N tracer studies also showed that BSP accumulation is an important factor in N partitioning from senescing leaves to bark. Thus, BSP accumulation has a role in N remobilization during N partitioning both from senescing leaves to bark and from bark to expanding shoots once growth commences following dormancy. The bark transcriptome during BSP catabolism and N remobilization was enriched in genes associated with auxin transport and signaling, and manipulation of the source of auxin or auxin transport revealed a role for auxin in regulating BSP catabolism and N remobilization. Therefore, N remobilization appears to be regulated by auxin produced in expanding buds and shoots that is transported to bark where it regulates protease gene expression and BSP catabolism.
PMID: 32161967
J Exp Bot , IF:5.908 , 2020 Jul , V71 (15) : P4393-4404 doi: 10.1093/jxb/eraa033
Signaling pathways underlying nitrogen-dependent changes in root system architecture: from model to crop species.
Molecular Plant Nutrition, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Stadt Seeland, OT Gatersleben, Germany.
Among all essential mineral elements, nitrogen (N) is required in the largest amounts and thus is often a limiting factor for plant growth. N is taken up by plant roots in the form of water-soluble nitrate, ammonium, and, depending on abundance, low-molecular weight organic N. In soils, the availability and composition of these N forms can vary over space and time, which exposes roots to various local N signals that regulate root system architecture in combination with systemic signals reflecting the N nutritional status of the shoot. Uncovering the molecular mechanisms underlying N-dependent signaling provides great potential to optimize root system architecture for the sake of higher N uptake efficiency in crop breeding. In this review, we summarize prominent signaling mechanisms and their underlying molecular players that derive from external N forms or the internal N nutritional status and modulate root development including root hair formation and gravitropism. We also compare the current state of knowledge of these pathways between Arabidopsis and graminaceous plant species.
PMID: 31970412
J Exp Bot , IF:5.908 , 2020 Jul , V71 (15) : P4373-4379 doi: 10.1093/jxb/erz554
NRT1.1s in plants: functions beyond nitrate transport.
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.; Guangdong Laboratory of Lingnan Modern Agriculture, Guangzhou, China.
Arabidopsis AtNRT1.1 (CHL1/AtNPF6.3) is the first nitrate transporter identified in plants and was initially found to play a role in nitrate uptake and transport. AtNRT1.1 also displays auxin transport activity and mediates nitrate-modulated root development, suggesting that it has transport capacity for multiple substrates. Subsequent work revealed that AtNRT1.1 can respond to environmental nitrate fluctuations by altering its nitrate transport activity, modulated by phosphorylation, leading to the critical finding that AtNRT1.1 acts as a transceptor for nitrate sensing. Recent studies have revealed how OsNRT1.1B, the functional homologue of AtNRT1.1 in rice, mediates nitrate signal transduction from the plasma membrane to the nucleus, and how OsNRT1.1B integrates the nitrate and phosphate signaling networks. OsNRT1.1B has also been shown to be involved in regulating the root microbiota to facilitate organic nitrogen mineralization in soil, thus mediating plant-microbe interactions. Furthermore, the divergent functions of OsNRT1.1A and OsNRT1.1B in regulating nitrogen use in rice suggest that the function of NRT1.1 is still far from fully understood. In this review, we focus on the most recent progress on the molecular mechanisms of NRT1.1s in plants, with the aim of providing an up-to-date view of the versatile functions of NRT1.1 in nitrogen utilization in plants.
PMID: 31832669
Development , IF:5.611 , 2020 Jul , V147 (13) doi: 10.1242/dev.193672
The people behind the papers - Priyanka Govindaraju and Enrico Scarpella.
The veins are the vascular networks of plant leaves, functioning as channels for transport of signals and nutrients. A new paper in Development investigates how the spatial regulation of auxin transport contributes to vein patterning in Arabidopsis We caught up with first author Priyanka Govindaraju and her supervisor Enrico Scarpella, Associate Professor at the Department of Biological Sciences, University of Alberta in Edmonton, Canada, to find out more about the work.
PMID: 32632037
Development , IF:5.611 , 2020 Jul , V147 (14) doi: 10.1242/dev.187781
An auxin transport network underlies xylem bridge formation between the hemi-parasitic plant Phtheirospermum japonicum and host Arabidopsis.
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.; Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan.; Institute for Research Initiatives, Division for Research Strategy, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan ken.shirasu@riken.jp.
Parasitic plants form vascular connections with host plants for efficient material transport. The haustorium is the responsible organ for host invasion and subsequent vascular connection. After invasion of host tissues, vascular meristem-like cells emerge in the central region of the haustorium, differentiate into tracheary elements and establish a connection, known as a xylem bridge, between parasite and host xylem systems. Despite the importance of this parasitic connection, the regulatory mechanisms of xylem bridge formation are unknown. Here, we show the role of auxin and auxin transporters during the process of xylem bridge formation using an Orobanchaceae hemiparasitic plant, Phtheirospermum japonicum The auxin response marker DR5 has a similar expression pattern to tracheary element differentiation genes in haustoria. Auxin transport inhibitors alter tracheary element differentiation in haustoria, but biosynthesis inhibitors do not, demonstrating the importance of auxin transport during xylem bridge formation. The expression patterns and subcellular localization of PIN family auxin efflux carriers and AUX1/LAX influx carriers correlate with DR5 expression patterns. The cooperative action of auxin transporters is therefore responsible for controlling xylem vessel connections between parasite and host.
PMID: 32586973
Development , IF:5.611 , 2020 Jul , V147 (13) doi: 10.1242/dev.187666
Vein patterning by tissue-specific auxin transport.
Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB T6G 2E9, Canada.; Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton AB T6G 2E9, Canada enrico.scarpella@ualberta.ca.
Unlike in animals, in plants, vein patterning does not rely on direct cell-cell interaction and cell migration; instead, it depends on the transport of the plant hormone auxin, which in turn depends on the activity of the PIN-FORMED1 (PIN1) auxin transporter. The current hypotheses of vein patterning by auxin transport propose that, in the epidermis of the developing leaf, PIN1-mediated auxin transport converges to peaks of auxin level. From those convergence points of epidermal PIN1 polarity, auxin would be transported in the inner tissues where it would give rise to major veins. Here, we have tested predictions of this hypothesis and have found them unsupported: epidermal PIN1 expression is neither required nor sufficient for auxin transport-dependent vein patterning, whereas inner-tissue PIN1 expression turns out to be both required and sufficient for auxin transport-dependent vein patterning. Our results refute all vein patterning hypotheses based on auxin transport from the epidermis and suggest alternatives for future tests.
PMID: 32493758
J Integr Plant Biol , IF:4.885 , 2020 Jul doi: 10.1111/jipb.12992
Integrated metabolo-transcriptomics and functional characterization reveals that the wheat auxin receptor TIR1 negatively regulates defense against Fusarium graminearum.
State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, China.; College of Information Science and Engineering, Shandong Agricultural University, Tai'an, 271018, China.
Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schw.) Perch] results in large yield losses in annual global wheat production. Although studies have identified a number of wheat FHB resistance genes, a deeper understanding of the mechanisms underlying host plant resistance to F. graminearum is required for the control of FHB. Here, an integrated metabolomics and transcriptomics analysis of infected wheat plants (Triticum aestivum L.) enabled identification of 789 differentially accumulated metabolites, including flavonoids, phenolamides, tryptamine derivatives, and phytohormones, and revealed altered expression of more than 100 genes that function in the biosynthesis or regulation of these pathways. Our data regarding the effects of F. graminearum infection on flavonoids and auxin signaling led to follow-up experiments that showed that exogenous kaempferide and apigenin application on spikes increased wheat resistance to FHB, while exogenous auxin treatment increased FHB susceptibility. RNAi-mediated knockdown of the gene encoding the auxin receptor, TaTIR1, increased FHB resistance. Our data supported the use of TaTIR1 knockdown in controlling FHB. Our study provides insights on the wheat response to F. graminearum infection and its FHB resistance mechanisms while illustrating the potential of TaTIR1 knockdown in increasing FHB resistance during crop improvement programs. This article is protected by copyright. All rights reserved.
PMID: 32678930
Int J Mol Sci , IF:4.556 , 2020 Jul , V21 (15) doi: 10.3390/ijms21155284
Shade Effects on Peanut Yield Associate with Physiological and Expressional Regulation on Photosynthesis and Sucrose Metabolism.
Guangdong Key Laboratory of Plant Molecular Breeding, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Agriculture, South China Agricultural University, Guangzhou 510642, China.; Department of Genetics, University of Georgia, Athens, GA, 30602, USA.
Intercropping improves land utilization with more crops grown together; however, shorter crops in intercropping experience stress, being shaded by the taller crops. Systematic changes in phenotype, physiology, yield, and gene regulation under shade stress in peanut are largely unknown, although shade responses have been well analyzed in model plants. We exposed peanut plants to simulated 40% and 80% shade for 15 and 30 days at the seedling stage, flowering stage, and both stages. Shade caused the increased elongation growth of the main stem, internode, and leaf, and elongation was positively associated with auxin levels. Shade stress reduced peanut yield. Further comparative RNA-seq analyses revealed expressional changes in many metabolism pathways and common core sets of expressional regulations in all shade treatments. Expressional downregulation of most genes for light-harvesting and photosynthesis agreed with the observed decreased parameters of photosynthesis processes. Other major regulations included expressional downregulation of most core genes in the sucrose and starch metabolism, and growth-promoting genes in plant hormone signal pathways. Together, the results advance our understanding of physiological and molecular regulation in shade avoidance in peanut, which could guide the breeding designing in the intercropping system.
PMID: 32722456
Int J Mol Sci , IF:4.556 , 2020 Jul , V21 (14) doi: 10.3390/ijms21144876
Effect of Auxin (IAA) on the Fast Vacuolar (FV) Channels in Red Beet (Beta vulgaris L.) Taproot Vacuoles.
Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, 40-032 Katowice, Poland.
In contrast to the well-studied effect of auxin on the plasma membrane K(+) channel activity, little is known about the role of this hormone in regulating the vacuolar K(+) channels. Here, the patch-clamp technique was used to investigate the effect of auxin (IAA) on the fast-activating vacuolar (FV) channels. It was found that the macroscopic currents displayed instantaneous currents, which at the positive potentials were about three-fold greater compared to the one at the negative potentials. When auxin was added to the bath solution at a final concentration of 1 microM, it increased the outward currents by about 60%, but did not change the inward currents. The imposition of a ten-fold vacuole-to-cytosol KCl gradient stimulated the efflux of K(+) from the vacuole into the cytosol and reduced the K(+) current in the opposite direction. The addition of IAA to the bath solution with the 10/100 KCl gradient decreased the outward current and increased the inward current. Luminal auxin reduced both the outward and inward current by approximately 25% compared to the control. The single channel recordings demonstrated that cytosolic auxin changed the open probability of the FV channels at the positive voltages to a moderate extent, while it significantly increased the amplitudes of the single channel outward currents and the number of open channels. At the positive voltages, auxin did not change the unitary conductance of the single channels. We suggest that auxin regulates the activity of the fast-activating vacuolar (FV) channels, thereby causing changes of the K(+) fluxes across the vacuolar membrane. This mechanism might serve to tightly adjust the volume of the vacuole during plant cell expansion.
PMID: 32664260
Int J Mol Sci , IF:4.556 , 2020 Jul , V21 (13) doi: 10.3390/ijms21134751
YUCCA-Mediated Biosynthesis of the Auxin IAA Is Required during the Somatic Embryogenic Induction Process in Coffea canephora.
Unidad de Bioquimica y Biologia Molecular de Plantas, Centro de Investigacion Cientifica de Yucatan, A.C. Calle 43 No. 130 x 32 y 344 Col. Chuburna de Hidalgo, Merida C.P. 97205, Mexico.; Catedratico CONACYT, Unidad de Bioquimica y Biologia Molecular de Plantas, Centro de Investigacion Cientifica de Yucatan, Merida C.P. 97205, Mexico.
Despite the existence of considerable research on somatic embryogenesis (SE), the molecular mechanism that regulates the biosynthesis of auxins during the SE induction process remains unknown. Indole-3-acetic acid (IAA) is an auxin that is synthesized in plants through five pathways. The biosynthetic pathway most frequently used in this synthesis is the conversion of tryptophan to indol-3-pyruvic acid (IPA) by tryptophan aminotransferase of Arabidopsis (TAA) followed by the conversion of IPA to IAA by enzymes encoded by YUCCA (YUC) genes of the flavin monooxygenase family; however, it is unclear whether YUC-mediated IAA biosynthesis is involved in SE induction. In this study, we report that the increase of IAA observed during SE pre-treatment (plants in MS medium supplemented with 1-naphthaleneacetic acid (NAA) 0.54 microM and kinetin (Kin) 2.32 microM for 14 days) was due to its de novo biosynthesis. By qRT-PCR, we demonstrated that YUC gene expression was consistent with the free IAA signal found in the explants during the induction of SE. In addition, the use of yucasin to inhibit the activity of YUC enzymes reduced the signal of free IAA in the leaf explants and dramatically decreased the induction of SE. The exogenous addition of IAA restored the SE process in explants treated with yucasin. Our findings suggest that the biosynthesis and localization of IAA play an essential role during the induction process of SE in Coffea canephora.
PMID: 32635392
J Biol Chem , IF:4.238 , 2020 Jul doi: 10.1074/jbc.RA120.014104
Auxin-transporting ABC transporters are defined by a conserved D/E-P motif regulated by a prolylisomerase.
University of Fribourg, Switzerland.; Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poland.; Microbiology, Institute of Plant and Microbial Biology, Switzerland.; Department of Biology, University of Fribourg, Switzerland.
The plant hormone auxin must be transported throughout plants in a cell-to-cell manner to affect its various physiological functions. ABCB transporters are critical for this polar auxin distribution, but the regulatory mechanisms controlling their function is not fully understood. The auxin transport activity of ABCB1 was suggested to be regulated by a physical interaction with FKBP42/Twisted Dwarf1 (TWD1), a peptidylprolyl cis-transisomerase (PPIase), but all attempts to demonstrate such a PPIase activity by TWD1 have failed so far.By using a structure-based approach, we identified several surface-exposed proline residues in the nucleotide binding domain and linker of Arabidopsis ABCB1, mutations of which do not alter ABCB1 protein stability or location but do affect its transport activity. P1008 is part of a conserved signature D/E-P motif that seems to be specific for Auxin-TransportingABCBs, which we now refer to as ATAs. Mutation of the acidic residue also abolishes auxin transport activity by ABCB1. All higher plant ABCBs for which auxin transport has been conclusively proven carry this conserved motif, underlining its predictive potential. Introduction of this D/E-P motif into malate importer, ABCB14, increases both its malate and its background auxin transport activity, suggesting that this motif has an impact on transport capacity. The D/E-P1008 motif is also important for ABCB1-TWD1 interactions and activation of ABCB1-mediated auxin transport by TWD1.In summary, our data imply a new function for TWD1 acting as a putative activator of ABCB-mediated auxin transport by cis-trans isomerization of peptidyl-prolyl bonds.
PMID: 32699109
Microorganisms , IF:4.152 , 2020 Jul , V8 (7) doi: 10.3390/microorganisms8071005
The Response of Maize to Inoculation with Arthrobacter sp. and Bacillus sp. in Phosphorus-Deficient, Salinity-Affected Soil.
Leibniz Institute of Vegetable and Ornamental Crops Grossbeeren, Theodor- Echtermeyer-Weg 1, 14979 Grossbeeren, Germany.; Department of Plant Biology, Faculty of Sciences, University of Douala, P.O. Box 24157 Douala, Cameroon.; Faculty of Life sciences Humboldt-University of Berlin, Invalidenstrasse 42, 10115 Berlin, Germany.; Institute for National and International Plant Health, Julius Kuehn-Institute-Federal Research Centre for Cultivated Plants, Messeweg 11/12, 38104 Braunschweig, Germany.; Algorithms in Bioinformatics, Center for Bioinformatics, University of Tuebingen, Sand 14, 72076 Tuebingen, Germany.; Laboratory of Growth Regulators, The Czech Academy of Sciences, Institute of Experimental Botany and Palacky University, Slechtitelu 27, CZ-783 71 Olomouc, Czech Republic.
Salinity and phosphorus (P) deficiency are among the most serious soil factors constraining crop productivity. A proposed strategy for alleviating these stresses is supporting plants by inoculation with growth-promoting rhizobacteria (PGPR). Here, a comparison of the ability of two maize composite and two F1 hybrid varieties to tolerate a P deficiency in either a saline or a non-saline environment showed that the uptake of nutrients by all four entries was significantly reduced by the imposition of both soil salinity and P deficiency, and that their growth was compromised to a similar extent. Subsequently, the ameliorative effect of inoculation with three strains of either Arthrobacter sp. or Bacillus sp. in an environment, which suffered simultaneously from salinity and P deficiency, was investigated. Inoculation with each of the strains was found to limit the plants' uptake of sodium cations, to increase their uptake of potassium cations, and to enhance their growth. The extent of the growth stimulation was more pronounced for the composite varieties than for the F1 hybrid ones, although the amount of biomass accumulated by the latter, whether the plants had been inoculated or not, was greater than that of the former varieties. When the bacterial strains were cultured in vitro, each of them was shown as able to produce the phytohormones auxin, abscisic acid, gibberellins, and cytokinins. The implication is that since the presence in the rhizospere of both Arthrobacter sp. and Bacillus sp. strains can support the growth of maize in salinity-affected and P deficient soils in a genotype-dependent fashion, it is important to not only optimize the PGPR strain used for inoculation, but also to select maize varieties which can benefit most strongly from an association with these bacteria.
PMID: 32635586
Plant Cell Physiol , IF:4.062 , 2020 Jul doi: 10.1093/pcp/pcaa098
An evolutionarily primitive and distinct auxin metabolism in the lycophyte Selaginella moellendorffii.
Department of Bioregulation and Biointeraction, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan (S.K. and Y.A.).; Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan (S.D.C.).; JSPS International Research Fellow (S.D.C.).; Department of Applied Biological Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan (A.W.).; Department of Biochemistry, Okayama University of Science, Okayama, Japan (K.H.).; Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, Japan (H.K.).; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan (H.K.).
Auxin is a key regulator of plant growth and development. Indole-3-acetic acid (IAA), a plant auxin, is mainly produced from tryptophan via indole-3-pyruvate (IPA) in both bryophytes and angiosperms. Angiosperms have multiple, well documented IAA inactivation pathways, involving conjugation to IAA-aspartate/glutamate by the GH3 auxin-amido synthetases, and oxidation to 2-oxoindole-3-acetic acid (oxIAA) by the DAO proteins. However, IAA biosynthesis and inactivation processes remain elusive in lycophytes, an early lineage of spore producing vascular plants. In this article, we studied IAA biosynthesis and inactivation in the lycophyte Selaginella moellendorffii. We demonstrate that S. moellendorffii mainly produces IAA from the IPA pathway for the regulation of root growth and response to high temperature, similar to the angiosperm Arabidopsis. However, S. moellendorffii exhibits a unique IAA metabolite profile with high IAA-aspartate and low oxIAA levels, distinct from Arabidopsis and the bryophyte Marchantia polymorpha, suggesting that the GH3 family is integral for IAA homeostasis in the lycophytes. The DAO homologs in S. moellendorffii share only limited similarity to the well characterized rice and Arabidopsis DAO proteins. We therefore suggest that these enzymes may have a limited role in IAA homeostasis in S. moellendorffii compared to angiosperms. We provide new insights into the functional diversification of auxin metabolic genes in the evolution of land plants.
PMID: 32697828
Ann Bot , IF:4.005 , 2020 Jul doi: 10.1093/aob/mcaa121
Associations between phytohormones and cellulose biosynthesis in land plants.
School of Biosciences, University of Melbourne, Parkville, Victoria, Australia.; Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada, USA.; Department of Chemistry, University of Nevada, Reno, Nevada, USA.
BACKGROUND: Phytohormones are small molecules that regulate virtually every aspect of plant growth and development; from basic cellular processes, such as cell expansion and division, to whole plant environmental responses. While the phytohormone levels and distribution thus tell the plant how to adjust itself, the corresponding growth alterations are actuated by cell wall modification/synthesis and internal turgor. Plant cell walls are complex polysaccharide-rich extracellular matrixes that surround all plant cells. Among the cell wall components, cellulose is typically the major polysaccharide, and is the load-bearing structure of the walls. Hence, the cell wall distribution of cellulose, which is synthesized by large Cellulose Synthase protein complexes at the cell surface, directs plant growth. SCOPE: Here, we review the relationships between key phytohormone classes and cellulose deposition in plant systems. We present the core signaling pathways associated with each phytohormone and discuss the current understanding of how these signaling pathways impact cellulose biosynthesis with a particular focus on transcriptional and post-translational regulation. Because cortical microtubules underlying the plasma membrane significantly impact the trajectories of Cellulose Synthase Complexes, we also discuss the current understanding of how phytohormone signaling impacts the cortical microtubule array. CONCLUSION: Given the importance of cellulose deposition and phytohormone signaling in plant growth and development, one would expect that there is substantial cross-talk between these processes; however, mechanisms for many of these relationships remain unclear and should be considered as the target of future studies.
PMID: 32619216
Sci Rep , IF:3.998 , 2020 Jul , V10 (1) : P10866 doi: 10.1038/s41598-020-66483-y
Genome-wide identification and expression profiling of the YUCCA gene family in Malus domestica.
College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China.; College of Horticulture, Henan Agriculture University, Zhengzhou, Henan, 450002, China.; Gaotou Township People's Government of Wuji County, Shijiazhuang, Hebei, 050000, China.; Taiyuan Academy of Agricultural Sciences, Taiyuan, Shannxi, 030000, China.; Weinan Agro-Tech Extension Center, Weinan, Shaanxi, 714000, China.; Silkworm Tea Fruit Technology Extension Center in Nanzheng District, Hanzhong, 723100, Shaanxi, China.; College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China. anna206@nwsuaf.edu.cn.; College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China. anna206@nwsuaf.edu.cn.
The plant hormone auxin is essential for plant growth and development. YUCCA proteins catalyse the rate-limiting step for endogenous auxin biosynthesis. In this study, we isolated 20 MdYUCCA genes from apple genome. MdYUCCA6a, MdYUCCA8a, and MdYUCCA10a were expressed in most organs and could support whole plant basal auxin synthesis. MdYUCCA4a, MdYUCCA10b, and MdYUCCA11a expression indicated roles for these genes in auxin biosynthesis in vegetative organs. MdYUCCA2b, MdYUCCA11b, and MdYUCCA11d were mainly expressed in flower organs. High temperature induced the expression of MdYUCCA4a, MdYUCCA6a, MdYUCCA8a, and MdYUCCA10a, and down-regulated the expression of MdYUCCA2b and MdYUCCA6b. Dual-luciferase assay indicated that MdPIF4 could trans-activate the MdYUCCA8a promoter. Overexpression of MdYUCCA8a increased IAA content, increased stem height, enhanced apical dominance, and led to silique malformation. These results provide a foundation for further investigation of the biological functions of apple MdYUCCAs.
PMID: 32616911
Analyst , IF:3.978 , 2020 Jul doi: 10.1039/d0an00269k
A fish scale-like magnetic nanomaterial as a highly efficient sorbent for monitoring the changes in auxin levels under cadmium stress.
Ministry of Education Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350116, China. 196419@fzu.edu.cn zlan@fzu.edu.cn.; Ministry of Education Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350116, China. 196419@fzu.edu.cn zlan@fzu.edu.cn and Testing Center of Fuzhou University, Fuzhou, Fujian 350116, China.; College of Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350116, China.
Sorbents with high surface utilization and good dispersibility are of great importance for the extraction performance of magnetic solid-phase extraction (MSPE). In this study, a fish scale-like magnetic nanomaterial (Co@Co3O4/OCN) was synthesized, which can be used as a highly efficient MSPE sorbent due to its strong magnetism, special morphology, doping of N element, numerous micro-mesopore cavities and organic functional groups (hydroxyl and carboxyl). Furthermore, a Co@Co3O4/OCN-based MSPE method for monitoring the changes in the levels of three auxins (indole-3-acetic acid, indole-3-propionic acid and 3-indole butyric acid) was successfully established. Wide linear ranges (1.0-1000.0 pg mL-1) with good correlation coefficients (R > 0.9992), low limits of detection (LODs, 0.2-4.0 pg mL-1) and satisfactory repeatability (RSD
PMID: 32692339
Pest Manag Sci , IF:3.75 , 2020 Jul doi: 10.1002/ps.6007
Explore quinclorac resistance mechanisms in Echinochloa crus-pavonis from China.
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China.; Australian Herbicide Resistance Initiative, School of Agriculture and Environment, University of Western Australia, Crawley, Australia.; Agricultural Engineering Research Institute, Jiangsu University, Zhenjiang, China.
BACKGROUND: Barnyardgrass (Echinochloa spp.) is a global weed in rice fields. Quinclorac is commonly used to control barnyardgrass. However, due to persistent use, quinclorac resistance has evolved. We obtained quinclorac -susceptible (QS) and -resistant (QR1, QR2) lines from the progeny of a single resistant E. crus-pavonis for a resistance mechanism study. RESULTS: Line QR1 exhibited resistance to high quinclorac rates (up to 6400 g ha(-1) ), whereas line QR2 exhibited a resistance/susceptibility segregation ratio of 3:1 at the field or lower rates (400, 100 g ha(-1) ). Intriguingly, a lower level of (14) C-quinclorac metabolism and hence a higher level of (14) C-quinclorac translocation was observed in QR1 than QS plants. The basal expression levels of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase 2 (ACO2) genes did not differ significantly between the QR1 and QS lines. However, more expression of ACS and ACO genes was induced by quinclorac treatment in QS than in QR1. Basal levels of beta-cyanoalanine synthase (beta-CAS) gene expression were similar in QS and QR1 plants, but a greater level of down regulation was detected in QS than in QR1 plants after quinclorac treatment. CONCLUSION: These results indicate QR plants are less responsive to quinclorac than QS plants in terms of upregulating quinclorac metabolism and ethylene synthesis. Resistance in this E. crus-pavonis line is likely controlled by a single major gene, involving possibly an alteration in auxin signal perception/transduction to the ethylene biosynthesis pathway. The beta-CAS is unlikely to play a major role in quinclorac resistance in this particular population. This article is protected by copyright. All rights reserved.
PMID: 32652760
Plant Physiol Biochem , IF:3.72 , 2020 Jul , V154 : P581-589 doi: 10.1016/j.plaphy.2020.06.010
Molecular and structural insights into FaEXPA5, an alpha-expansin protein related with cell wall disassembly during ripening of strawberry fruit.
Programa de Doctorado en Ciencias Mencion Ingenieria Genetica, Instituto de Ciencias Biologicas, Universidad de Talca, Chile.; Instituto de Ciencias Biologicas, Universidad de Talca, Chile; Nucleo Cientifico Multidisciplinario-DI, Universidad de Talca, Chile. Electronic address: pramos@utalca.cl.; Multidisciplinary Agroindustry Research Laboratory, Instituto de Ciencias Biomedica, Facultad Ciencias de La Salud, Universidad Autonoma de Chile, Talca, Chile. Electronic address: luis.morales@uautonoma.cl.
Cell wall modification is one of the main factors that produce the tissue softening during ripening of many fruit including strawberry (Fragaria x ananassa). Expansins have been studied for over 20 years as a class of the important cell growth regulators, and in the last years these have been related with the fruit softening. In strawberry, five partial sequences of the expansins genes were described in the past, this analysis showed that FaEXP5 partial gene was present throughout fruit development, but was more strongly expressed during ripening. Now, we reported the full length of this alpha-expansin (FaEXPA5), whose had been related with fruit softening, and the protein structural was described by homology model. Their transcript accumulation during softening was confirmed by qRT-PCR, displaying a high accumulation rate during fruit ripening. In silico analysis of promoter sequence showed four ABA and two auxin cis-regulatory elements, potentially responsible for the expression patterns observed in response to the hormone treatments. Additionally, 3D protein model displayed two domains and one open groove characteristic of expansin structures. The protein-ligand interactions were evaluated by molecular dynamic (MD) simulation using three different long structure ligands (a cellulose fiber, a xyloglucan fiber (XXXG type), and a pectin fiber as control). Favorable interactions were observed with xyloglucan and cellulose, being cellulose the best ligand with lower RMSD value. Additionally, MD simulations showed that FaEXPA5 can interact with the ligands through residues present in the open groove along the two domains.
PMID: 32711363
BMC Genomics , IF:3.594 , 2020 Jul , V21 (1) : P523 doi: 10.1186/s12864-020-06930-2
Proteomic responses to progressive dehydration stress in leaves of chickpea seedlings.
Research Center for Plant Sciences, Ferdowsi University of Mashhad, Mashhad, Iran. vessal@um.ac.ir.; Plant Biotechnology and Breeding Department, College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.; The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6001, Australia.
BACKGROUND: Chickpea is an important food legume crop with high protein levels that is widely grown in rainfed areas prone to drought stress. Using an integrated approach, we describe the relative changes in some physiological parameters and the proteome of a drought-tolerant (MCC537, T) and drought-sensitive (MCC806, S) chickpea genotype. RESULTS: Under progressive dehydration stress, the T genotype relied on a higher relative leaf water content after 3 and 5 d (69.7 and 49.3%) than the S genotype (59.7 and 40.3%) to maintain photosynthetic activities and improve endurance under stress. This may have been facilitated by greater proline accumulation in the T genotype than the S genotype (14.3 and 11.1 mumol g(- 1) FW at 5 d, respectively). Moreover, the T genotype had less electrolyte leakage and lower malondialdehyde contents than the S genotype under dehydration stress, indicating greater membrane stability and thus greater dehydration tolerance. The proteomic analysis further confirmed that, in response to dehydration, the T genotype activated more proteins related to photosynthesis, stress response, protein synthesis and degradation, and gene transcription and signaling than the S genotype. Of the time-point dependent proteins, the largest difference in protein abundance occurred at 5 d, with 29 spots increasing in the T genotype and 30 spots decreasing in the S genotype. Some of the identified proteins-including RuBisCo, ATP synthase, carbonic anhydrase, psbP domain-containing protein, L-ascorbate peroxidase, 6-phosphogluconate dehydrogenase, elongation factor Tu, zinc metalloprotease FTSH 2, ribonucleoproteins and auxin-binding protein-may play a functional role in drought tolerance in chickpea. CONCLUSIONS: This study highlights the significance of genotype- and time-specific proteins associated with dehydration stress and identifies potential resources for molecular drought tolerance improvement in chickpea.
PMID: 32727351
BMC Plant Biol , IF:3.497 , 2020 Jul , V20 (1) : P335 doi: 10.1186/s12870-020-02544-8
Auxin mediates the touch-induced mechanical stimulation of adventitious root formation under windy conditions in Brachypodium distachyon.
Department of Chemistry, Seoul National University, Seoul, 08826, South Korea.; Department of Biology Education, Seoul National University, Seoul, 08826, South Korea.; Department of Chemistry, Seoul National University, Seoul, 08826, South Korea. cmpark@snu.ac.kr.; Plant Genomics and Breeding Institute, Seoul National University, Seoul, 08826, South Korea. cmpark@snu.ac.kr.
BACKGROUND: It is widely perceived that mechanical or thigmomorphogenic stimuli, such as rubbing and bending by passing animals, wind, raindrop, and flooding, broadly influence plant growth and developmental patterning. In particular, wind-driven mechanical stimulation is known to induce the incidence of radial expansion and shorter and stockier statue. Wind stimulation also affects the adaptive propagation of the root system in various plant species. However, it is unknown how plants sense and transmit the wind-derived mechanical signals to launch appropriate responses, leading to the wind-adaptive root growth. RESULTS: Here, we found that Brachypodium distachyon, a model grass widely used for studies on bioenergy crops and cereals, efficiently adapts to wind-mediated lodging stress by forming adventitious roots (ARs) from nonroot tissues. Experimental dissection of wind stimuli revealed that not bending of the mesocotyls but physical contact of the leaf nodes with soil particles triggers the transcriptional induction of a group of potential auxin-responsive genes encoding WUSCHEL RELATED HOMEOBOX and LATERAL ORGAN BOUNDARIES DOMAIN transcription factors, which are likely to be involved in the induction of AR formation. CONCLUSIONS: Our findings would contribute to further understanding molecular mechanisms governing the initiation and development of ARs, which will be applicable to crop agriculture in extreme wind climates.
PMID: 32678030
BMC Plant Biol , IF:3.497 , 2020 Jul , V20 (1) : P311 doi: 10.1186/s12870-020-02504-2
Small Auxin Up RNAs influence the distribution of indole-3-acetic acid and play a potential role in increasing seed size in Euryale ferox Salisb.
School of Pharmacy, Nanjing University of Chinese Medicine, 138 xianlin Road, Nanjing, 210023, Jiangsu, China.; Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing, 210023, China.; School of Pharmacy, Nanjing University of Chinese Medicine, 138 xianlin Road, Nanjing, 210023, Jiangsu, China. qnwyjs@126.com.; Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing, 210023, China. qnwyjs@126.com.
BACKGROUND: Aquatic Euryale ferox Salisb. is an economically important crop in China and India. Unfortunately, low yield limitations seriously hinder market growth. Unveiling the control of seed size is of remarkable importance in improvement of crops. Here, we generated a new hybrid line (HL) with larger seeds by crossing South Gordon Euryale and North Gordon Euryale (WT) which hasn't been reported before. However, the functional genes and molecular mechanisms controlling the seed size in Euryale ferox Salisb. remain unclear. In this study, we focused on the differentially expressed genes in the auxin signal transduction pathway during fruit development between HL and WT to explore candidate regulatory genes participated in regulating seed size. RESULTS: Both concentration and localization of indole-3-acetic acid (IAA) at two growth stages of fruits of WT and HL were detected by LC-MS and immunofluorescence. Although IAA content between the two lines did not differ, IAA distribution was significantly different. To elucidate the mechanism and to seek the key genes underlying this difference, RNA-seq was performed on young fruits at the two selected growth stages, and differentially expressed genes related to the auxin transduction pathway were selected for further analysis. CONCLUSION: Hybrid Euryale ferox Salisb. expressed significant heterosis, resulting in non-prickly, thin-coated, large seeds, which accounted for the significantly larger yield of HL than that of WT. Our study indicated that Small Auxin Up RNAs (SAURs) -mediated localization of IAA regulates seed size in Euryale ferox Salisb. We found that some SAURs may act as a positive mediator of the auxin transduction pathway, thereby contributing to the observed heterosis.
PMID: 32620077
Planta , IF:3.39 , 2020 Jul , V252 (2) : P27 doi: 10.1007/s00425-020-03432-z
Physiological and transcriptomic analyses of brassinosteroid function in moso bamboo (Phyllostachys edulis) seedlings.
Basic Forestry and Proteomics Research Center, Forestry College, Fujian Agriculture and Forestry University, Fuzhou, China.; Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA.; College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, China.; Basic Forestry and Proteomics Research Center, Forestry College, Fujian Agriculture and Forestry University, Fuzhou, China. wenfeiwang@fafu.edu.cn.; College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, China. wenfeiwang@fafu.edu.cn.
MAIN CONCLUSION: This study demonstrates that brassinosteroid is essential for seedling and shoot growth in moso bamboo. The shoot of moso bamboo is known to grow extremely fast. The roles of phytohormones in such fast growth of bamboo shoot remain unclear. Here we reported that endogenous brassinosteroid (BR) is a major factor promoting bamboo shoot internode elongation. Reducing endogenous brassinosteroid level by its biosynthesis inhibitor propiconazole stunted shoot growth in seedling stage, whereas exogenous BR application promoted scale leaf elongation and the inclination of lamina joint of leaves and scale leaves. Genome-wide transcriptome analysis identified hundreds of genes whose expression levels are altered by BR and propiconazole in shoots and roots of bamboo seedling. The data show that BR regulates cell wall-related genes, hydrogen peroxide catabolic genes, and auxin-related genes. Our study demonstrates an essential role of BR in fast growth bamboo shoots and identifies a large number of BR-responsive genes in bamboo seedlings.
PMID: 32712728
J Plant Physiol , IF:3.013 , 2020 Jul , V252 : P153238 doi: 10.1016/j.jplph.2020.153238
The inhibition of SlIAA9 mimics an increase in endogenous auxin and mediates changes in auxin and gibberellin signalling during parthenocarpic fruit development in tomato.
Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1 Tsukuba, Ibaraki 305-8572, Japan; Department of Environmental Horticulture, The University of Seoul, Seoulsiripdaero 163, Dongdaemungu, Seoul 130743, South Korea.; Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1 Tsukuba, Ibaraki 305-8572, Japan.; RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama 230-0045, Japan.; RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama 230-0045, Japan; Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.; Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1 Tsukuba, Ibaraki 305-8572, Japan; Tsukuba Plant Innovation Research Center, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572, Japan.; Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1 Tsukuba, Ibaraki 305-8572, Japan; Tsukuba Plant Innovation Research Center, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572, Japan. Electronic address: ezura.hiroshi.fa@u.tsukuba.ac.jp.
Parthenocarpic fruit formation can be achieved through the inhibition of SlIAA9, a negative regulator of auxin signalling in tomato plant. During early fruit development under SlIAA9 inhibition, cell division and cell expansion were observed. Bioactive gibberellin (GA) accumulated, but indole-3-acetic acid (IAA) and trans-zeatin did not accumulate substantially. Furthermore, under SlIAA9 inhibition, auxin-responsive genes such as SlIAA2, -3, and -14 were upregulated, and SlARF7 was downregulated. These results indicate that SlIAA9 inhibition mimics an increase in auxin. The auxin biosynthesis genes SlTAR1, ToFZY, and ToFZY5 were stimulated by an increase in auxin and by auxin mimicking under SlIAA9 inhibition. However, SlTAR2 and ToFZY2 were upregulated only by pollination followed by high IAA accumulation. These results suggest that SlTAR2 and ToFZY2 play an important role in IAA synthesis in growing ovaries. GA synthesis was also activated by SlIAA9 inhibition through both the early-13-hydroxylation (for GA1 synthesis) and non-13-hydroxylation (GA4) pathways, indicating that fruit set caused by SlIAA9 inhibition was partially mediated by the GA pathway. SlIAA9 inhibition induced the expression of GA inactivation genes as well as GA biosynthesis genes except SlCPS during early parthenocarpic fruit development in tomato. This result suggests that inactivation genes play a role in fine-tuning the regulation of bioactive GA accumulation.
PMID: 32707453
J Plant Physiol , IF:3.013 , 2020 Aug , V251 : P153225 doi: 10.1016/j.jplph.2020.153225
Hormonal interplay in the regulation of fruit ripening and cold acclimation in avocados.
Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Faculty of Biology, Av. Diagonal 643, E-08028, Barcelona, Spain; Research Institute of Nutrition and Food Safety, University of Barcelona, Faculty of Biology, Av. Diagonal 643, E-08028, Barcelona, Spain.; Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Faculty of Biology, Av. Diagonal 643, E-08028, Barcelona, Spain; Research Institute of Nutrition and Food Safety, University of Barcelona, Faculty of Biology, Av. Diagonal 643, E-08028, Barcelona, Spain. Electronic address: smunne@ub.edu.
Avocados (Persea americana Mill.) are climacteric fruits, the ripening of which during postharvest at room temperature is strongly ethylene dependent. However, the role of other phytohormones in the modulation of postharvest ripening of avocados is still poorly understood. The optimal ripening state of avocados is attained a few days after harvest depending on the genotype, growing region and initial maturity stage of the fruit, and cold temperature storage is commonly used to delay this process. Here, we hypothesized that the ripening of avocados at room temperature may be governed not only by ethylene, but also by other phytohormones. With this aim, we analyzed the hormonal profiling of avocados subjected to either 4 degrees C and 25 degrees C during 10 days of postharvest. A biphasic response was observed during postharvest ripening of avocados at room temperature. While ethylene alone appeared to govern fruit ripening during the first transfer from cold to room temperature, a complex hormonal interplay occurred during ripening of avocados leading to a progressive fruit softening at room temperatures. Aside from ethylene, auxin, gibberellins, jasmonates and ABA appeared to be involved in avocado fruit ripening during postharvest at room temperature. Cold storage for a period of 10 days inhibited this hormonal response related to ripening. Furthermore, avocados stored at cold temperatures underwent a quick response in order to tolerate cold stress leading to changes in endogenous ABA and jasmonates. We conclude that a complex hormonal interplay, rather than ethylene alone, modulates postharvest ripening of avocados and that cold storage can effectively be employed as a technique to prevent avocados from a rapid ripening thanks to the cold stress tolerance mechanisms deployed by fruits through multiple hormonal regulation.
PMID: 32653729
Biochem Biophys Res Commun , IF:2.985 , 2020 Jul , V527 (4) : P1033-1038 doi: 10.1016/j.bbrc.2020.05.031
Role of Arabidopsis INDOLE-3-ACETIC ACID CARBOXYL METHYLTRANSFERASE 1 in auxin metabolism.
Department of Bioregulation and Biointeraction, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan.; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.; Department of Biological Production Science, United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan.; Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, 92093-0116, USA.; Department of Biochemistry, Okayama University of Science, Okayama, 700-0005, Japan.; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan; Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, 183-8509, Japan. Electronic address: kasahara@go.tuat.ac.jp.
The phytohormone auxin regulates a wide range of developmental processes in plants. Indole-3-acetic acid (IAA) is the main auxin that moves in a polar manner and forms concentration gradients, whereas phenylacetic acid (PAA), another natural auxin, does not exhibit polar movement. Although these auxins occur widely in plants, the differences between IAA and PAA metabolism remain largely unknown. In this study, we investigated the role of Arabidopsis IAA CARBOXYL METHYLTRANSFERASE 1 (IAMT1) in IAA and PAA metabolism. IAMT1 proteins expressed in Escherichia coli could convert both IAA and PAA to their respective methyl esters. Overexpression of IAMT1 caused severe auxin-deficient phenotypes and reduced the levels of IAA, but not PAA, in the root tips of Arabidopsis, suggesting that IAMT1 exclusively metabolizes IAA in vivo. We generated iamt1 null mutants via CRISPR/Cas9-mediated genome editing and found that the single knockout mutants had normal auxin levels and did not exhibit visibly altered phenotypes. These results suggest that other proteins, namely the IAMT1 homologs in the SABATH family of carboxyl methyltransferases, may also regulate IAA levels in Arabidopsis.
PMID: 32444138
Biochem Biophys Res Commun , IF:2.985 , 2020 Jul , V527 (4) : P935-940 doi: 10.1016/j.bbrc.2020.05.049
CIRCADIAN CLOCK ASSOCIATED 1 gates morning phased auxin response in Arabidopsis thaliana.
College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China.; College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China. Electronic address: zqzhu@njnu.edu.cn.
Circadian clock controls plant behaviors to anticipate day-night switch and keeps plant fitness. Here, we reported that plant response to auxin is also strictly governed by clock. The amplitude of auxin-responsive gene expressions gradually declined from morning to the dusk, and then enhanced from dusk to dawn. Plants with defects in both CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and its closest homologue LATE ELONGATED HYPOCOTYL (LHY) (cca1 lhy) showed comparable responses to auxin at different time points in consecutive days, suggesting that CCA1 and LHY were required for gating auxin responses. Moreover, CCA1/LHY physically interacted with the core transcriptional repressors (Aux/IAA proteins), which might further modulate plant sensitivity to auxin. Taken together, we demonstrate that the central morning phased circadian oscillator CCA1 plays a pivotal role in gating auxin response.
PMID: 32430181
Gene , IF:2.984 , 2020 Jul , V758 : P144942 doi: 10.1016/j.gene.2020.144942
Transcription factor LkWOX4 is involved in adventitious root development in Larix kaempferi.
State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China; College of Bioengineering and Biotechnology, Tianshui Normal University, Gansu 741000, China.; State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.; Department of Horticultural Science, North Carolina State University, Raleigh 27695, USA.; State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China. Electronic address: larch_rif@163.com.
WUSCHEL-related homeobox4 (WOX4) plays important roles in vascular formation and adventitious root (AR) development. Here, we cloned the WOX4 from the AR of Larix kaempferi, whose cDNA is 1452 bp in length and encodes 483 amino acids. LkWOX4 is mainly expressed in the layer formation area of the stem at 10 days after cutting and its expression levels in the middles and ends of the ARs were higher than that in the AR tips. The fused protein LkWOX4-GFP localized in the nucleus. The heterologous overexpression of LkWOX4 in 84 K poplar significantly increased AR numbers and decreased AR lengths. In LkWOX4 plants, the endogenous jasmonic acid and abscisic acid contents significantly decreased in stems, while the auxin, jasmonic acid and abscisic acid contents significantly increased in ARs. RNA-Seq of those LkWOX4 overexpression poplar plants showed that the expression of plant hormone signaling genes (ARF2, ARF3, ARF7 and ARF18), rooting-related transcription factors (WOX5, LBD29 and SCR) and root development-related genes (CYCD3, GRF1 and TAA1) were affected. Moreover, we found that LkWOX4 interacts with LkPAT18, LkACBP6, and LkCIP7 using yeast two hybrid screening. Thus, we found LkWOX4 involves in the AR initiation and development, which might be regulated through the IAA, JA and ABA signaling pathways.
PMID: 32640309
Plants (Basel) , IF:2.762 , 2020 Jul , V9 (8) doi: 10.3390/plants9080940
Photoreceptors Regulate Plant Developmental Plasticity through Auxin.
Plant Ecophysiology, Dept. Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Light absorption by plants changes the composition of light inside vegetation. Blue (B) and red (R) light are used for photosynthesis whereas far-red (FR) and green light are reflected. A combination of UV-B, blue and R:FR-responsive photoreceptors collectively measures the light and temperature environment and adjusts plant development accordingly. This developmental plasticity to photoreceptor signals is largely regulated through the phytohormone auxin. The phytochrome, cryptochrome and UV Resistance Locus 8 (UVR8) photoreceptors are inactivated in shade and/or elevated temperature, which releases their repression of Phytochrome Interacting Factor (PIF) transcription factors. Active PIFs stimulate auxin synthesis and reinforce auxin signalling responses through direct interaction with Auxin Response Factors (ARFs). It was recently discovered that shade-induced hypocotyl elongation and petiole hyponasty depend on long-distance auxin transport towards target cells from the cotyledon and leaf tip, respectively. Other responses, such as phototropic bending, are regulated by auxin transport and signalling across only a few cell layers. In addition, photoreceptors can directly interact with components in the auxin signalling pathway, such as Auxin/Indole Acetic Acids (AUX/IAAs) and ARFs. Here we will discuss the complex interactions between photoreceptor and auxin signalling, addressing both mechanisms and consequences of these highly interconnected pathways.
PMID: 32722230
Plants (Basel) , IF:2.762 , 2020 Jul , V9 (8) doi: 10.3390/plants9080931
Transcriptome Profiling Provides Molecular Insights into Auxin-Induced Adventitious Root Formation in Sugarcane (Saccharum spp. Interspecific Hybrids) Microshoots.
Key Laboratory of Sugarcane Biotechnology and Genetic Improvement (Guangxi), Ministry of Agriculture and Rural affairs/Guangxi Key Laboratory of Sugarcane Genetic Improvement/Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China.; Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin (CAGD), College of Resources and Environment, Southwest University, Chongqing 400715, China.; Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia 4072, QLD, Australia.
Adventitious root (AR) formation was enhanced following the treatment of sugarcane microshoots with indole-3-butyric acid (IBA) and 1-naphthalene acetic acid (NAA) combined, suggesting that auxin is a positive regulator of sugarcane microshoot AR formation. The transcriptome profile identified 1737 and 1268 differentially expressed genes (DEGs) in the basal tissues (5 mm) of sugarcane microshoots treated with IBA+NAA compared to nontreated control on the 3rd and 7th days post-auxin or water treatment (days post-treatment-dpt), respectively. To understand the molecular changes, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. This analysis showed that DEGs associated with the pathways were associated with plant hormone signaling, flavonoid and phenylpropanoid biosyntheses, cell cycle, and cell wall modification, and transcription factors could be involved in sugarcane microshoot AR formation. Furthermore, qRT-PCR analysis was used to validate the expression patterns of nine genes associated with root formation and growth, and the results were consistent with the RNA-seq results. Finally, a hypothetical hormonal regulatory working model of sugarcane microshoot AR formation is proposed. Our results provide valuable insights into the molecular processes associated with auxin-induced AR formation in sugarcane.
PMID: 32717893
Plants (Basel) , IF:2.762 , 2020 Jul , V9 (8) doi: 10.3390/plants9080929
Phloroglucinol Mediated Plant Regeneration of Ornithogalum dubium as the Sole "Hormone-Like Supplement" in Plant Tissue Culture Long-Term Experiments.
Institute of Technology Carlow, EnviroCORE, DSH, Kilkenny Road, R93 V960 Carlow, Ireland.
Tissue culture is an essential requirement in plant science to preserve genetic resources and to expand naturally occurring germplasm. A variety of naturally occurring and synthetic hormones are available to induce the processes of dedifferentiation and redifferentiation. Not all plant material is susceptible to tissue culture, and often complex media and hormone requirements are needed to achieve successful plant propagations. The availability of new hormones or chemicals acting as hormones are critical to the expansion of tissue culture potentials. Phloroglucinol has been shown to have certain hormone-like properties in a variety of studies. Ornithogalum dubium, an important geophyte species, was used to characterise the potential of phloroglucinol as the sole plant-like hormone in a tissue culture experiment. Tissue culture, plant regeneration, total phenolic and genetic variability were established by applying a variety of methods throughout long-term experiments. Phloroglucinol did induce callus formation and plant regeneration when used as the sole supplement in the media at a rate of 37%, thus demonstrating auxin/cytokines-like properties. Callus formation was of 3 types, friable and cellular, hard and compact, and a mixture of the two. The important finding was that direct somatogenesis did occur albeit more frequently on younger tissue, whereby rates of induction were up to 52%. It is concluded that phloroglucinol acts as a "hormone-like" molecule and can trigger direct embryogenesis without callus formation.
PMID: 32717803
Plants (Basel) , IF:2.762 , 2020 Jul , V9 (7) doi: 10.3390/plants9070868
In vivo Reporters for Visualizing Alternative Splicing of Hormonal Genes.
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic.; Functional Genomics and Proteomics of Plants, Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, 625 00 Brno, Czech Republic.
Rapid progress in plant molecular biology in recent years has uncovered the main players in hormonal pathways and characterized transcriptomic networks associated with hormonal response. However, the role of RNA processing, in particular alternative splicing (AS), remains largely unexplored. Here, using example genes involved in cytokinin signaling, brassinosteroid synthesis and auxin transport, we present a set of reporters devised to visualize their AS events in vivo. These reporters show a differential tissue-specific expression of certain transcripts and reveal that expression of some of the them can be changed by the application of the exogenous hormone. Finally, based on the characterized AS event of the PIN7 auxin efflux carrier, we designed a system that allows a rapid genetic screening for the factors upstream of this AS event. Our innovative toolset can be therefore highly useful for exploring novel regulatory nodes of hormonal pathways and potentially helpful for plant researchers focusing on developmental aspects of AS.
PMID: 32650629
Plants (Basel) , IF:2.762 , 2020 Jul , V9 (7) doi: 10.3390/plants9070849
tasiR-ARFs Production and Target Regulation during In Vitro Maize Plant Regeneration.
Departamento de Bioquimica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, 04510 Ciudad de Mexico, Mexico.; Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (CINVESTAV-IPN), Unidad de Genomica Avanzada (UGA-LANGEBIO), 36821 Irapuato Gto., Mexico.
During in vitro maize plant regeneration somatic cells change their normal fate and undergo restructuring to generate pluripotent cells able to originate new plants. Auxins are essential to achieve such plasticity. Their physiological effects are mediated by auxin response factors (ARFs) that bind auxin responsive elements within gene promoters. Small trans-acting (ta)-siRNAs, originated from miR390-guided TAS3 primary transcript cleavage, target ARF3/4 class (tasiR-ARFs). Here we found that TAS3b precursor as well as derived tasiR-ARFbD5 and tasiR-ARFbD6 display significantly lower levels in non-embryogenic callus (NEC), while TAS3g, miR390 and tasiR-ARFg are more abundant in the same tissue. However, Argonaute (AGO7) and leafbladeless 1 (LBLl) required for tasiR-ARF biogenesis showed significantly higher transcript levels in EC suggesting limited tasiR-ARF biogenesis in NEC. The five maize ARFs targeted by tasiR-ARFs were also significantly enriched in EC and accompanied by higher auxin accumulation with punctuate patterns in this tissue. At hormone half-reduction and photoperiod implementation, plant regeneration initiated from EC with transient TAS3g, miR390 and tasiR-ARFg increase. Upon complete hormone depletion, TAS3b became abundant and derived tasiR-ARFs gradually increased at further regeneration stages. ZmARF transcripts targeted by tasiR-ARFs, as well as AGO7 and LBL1 showed significantly lower levels during regeneration than in EC. These results indicate a dynamic tasiR-ARF mediated regulation throughout maize in vitro plant regeneration.
PMID: 32640631
Plants (Basel) , IF:2.762 , 2020 Jul , V9 (7) doi: 10.3390/plants9070837
Exogenous Carbon Compounds Modulate Tomato Root Development.
Grupo de Bioquimica y Biotecnologia, Area de Fisiologia Vegetal, Departamento de Ciencias Agrarias y del Medio Natural, ESTCE, Universitat Jaume I, 12071 Castellon, Spain.
NO3(-) is not only a nutrient, but also a signaling compound that plays an important role in several plant processes, like root development. The present study aimed to investigate the effect of three different exogenous C compounds (sucrose, glucose, 2-oxoglutarate) added to NO3(-) nutrition on C/N, auxin and antioxidant metabolisms in 10-day-old tomato seedlings. Sucrose and glucose supplementation enhanced primary root (PR) length, lateral root number and root density, while 2-oxoglutarate negatively affected them. This phenomenon was accompanied by a slight increase in NRT2.1 and GS1 gene expression, together with an increase in LAX2 and LAX3 and a decrease in LAX4 in the roots growing under sucrose and glucose sources. The addition of 2-oxoglutarate enhanced the expression of NiR, GDH, PEPC1, LAX1, LAX3 and the antioxidant gene SOD Cl. Taken together, these findings contribute to a better understanding of how these C sources can modulate N uptake and C/N, auxin and antioxidant gene expression, which could be useful for improving nitrogen use efficiency.
PMID: 32635257
Funct Plant Biol , IF:2.617 , 2020 Jul doi: 10.1071/FP20133
Altered localisation of ZmPIN1a proteins in plasma membranes responsible for enhanced-polar auxin transport in etiolated maize seedlings under microgravity conditions in space.
In the International Space Station experiment 'Auxin Transport', polar auxin transport (PAT) in shoots of etiolated maize (Zea mays L. cv. Golden Cross Bantam) grown under microgravity in space was substantially enhanced compared with those grown on Earth. To clarify the mechanism, the effects of microgravity on expression of ZmPIN1a encoding essential auxin efflux carrier and cellular localisation of its products were investigated. The amounts of ZmPIN1a mRNA in the coleoptiles and the mesocotyls in space-grown seedlings were almost the same as those in 1 g-grown seedlings, but its products were not. Immunohistochemical analysis with anti-ZmPIN1a antibody revealed a majority of ZmPIN1a localised in the basal side of plasma membranes of endodermal cells in the coleoptiles and the mesocotyls, and in the basal and lateral sides of plasma membranes in coleoptile parenchymatous cells, in which it directed towards the radial direction, but not towards the vascular bundle direction. Microgravity dramatically altered ZmPIN1a localisation in plasma membranes in coleoptile parenchymatous cells, shifting mainly towards the vascular bundle direction. These results suggest that mechanism of microgravity-enhanced PAT in maize shoots is more likely to be due to the enhanced ZmPIN1a accumulation and the altered ZmPIN1a localisation in parenchymatous cells of the coleoptiles.
PMID: 32635987
Plant Signal Behav , IF:1.671 , 2020 Jul : P1794394 doi: 10.1080/15592324.2020.1794394
Nitrate deficiency induces differential endocytosis in roots through NRT1.1.
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University , Tai'an, China.; College of Horticulture, Qingdao Agricultural University , Qingdao, China.
Roots grow asymmetrically, sometimes helically, around their growth direction likely to facilitate environmental sensing. We recently demonstrated that nitrate deficiency induces root coiling on horizontal surface through nitrate transporter/sensor NRT1.1 and PIN2- and AUX-mediated polar auxin transport. Here, we show that nitrate deficiency or NRT1.1 loss-of-function induces differential distribution of PIN2 between the future concave and concave sides in root epidermal cells. Treatment with pharmacological drugs suggests that enhanced endocytosis at the future convex side leads to reduced plasma membrane (PM) association of PIN2. A reduction of PIN2 at the PM would maintain a low auxin response to further enhance endocytosis at the convex side, leading to root coiling.
PMID: 32686596
Plant Signal Behav , IF:1.671 , 2020 Jul : P1794147 doi: 10.1080/15592324.2020.1794147
ABI3 plays a role in de-novo root regeneration from Arabidopsis thaliana callus cells.
Department of Biotechnology, St. Xavier's College , Kolkata, India.
Developmental plasticity and the ability to regenerate organs during the life cycle are a signature feature of plant system. De novo organogenesis is a common mode of plant regeneration and may occur directly from the explant or indirectly via callus formation. It is now evident that callus formation occurs through the root development pathway. In fact, callus cells behave like a group of root primordium cells that are under the control of exogenous auxin. Presence or absence of auxin decides the subsequent fate of these cells. While in presence of external supplementation of auxin they are maintained as root primordia cells, absence of exogenous auxin induces the callus cells into patterning, differentiation and finally root emergence. Here we show that in absence of functional ABI3, a prominent member of the B3 superfamily of transcription factors, root regeneration is compromised in Arabidopsis callus cells. In culture medium free of any exogenous hormone supplementation, while adventitious root emergence and growth was prominently observed in wild type cells, no such features were observed in abi3-6 cells. Expression of auxin-responsive AUX1 and GH3 genes was significantly reduced in abi3-6 cells, indicating that auxin levels or distribution may be altered in absence of ABI3.
PMID: 32662721
Plant Signal Behav , IF:1.671 , 2020 Jul , V15 (7) : P1771937 doi: 10.1080/15592324.2020.1771937
Immediate targets of ETTIN suggest a key role for pectin methylesterase inhibitors in the control of Arabidopsis gynecium development.
Laboratoire de Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCBL, INRAE, CNRS , Lyon, France.; Institute of Plant Sciences Paris-Saclay (IPS2), Universite Paris-Saclay, CNRS, INRAE, University of Evry , Orsay, France.; Institute of Plant Sciences Paris-Saclay (IPS2), Universite de Paris, CNRS, INRAE , Orsay, France.; UMR MIA-Paris, AgroParisTech, INRAE, Universite Paris-Saclay , Paris, France.
The control of gynecium development in Arabidopsis thaliana by the auxin response factor ETTIN (ETT) correlates with a reduction in the methylesterification of cell-wall pectins and a decrease in cell-wall stiffness in the valve tissues of the ovary. Here, we determine the list of genes rapidly regulated following the in-vivo activation of an ETT fusion protein, and show these to be significantly enriched in genes encoding cell-wall proteins, including several pectin methylesterases (PMEs) and pectin methylesterase inhibitors (PMEIs). We also perform a genome-wide scan for potential ETT-binding sites, and incorporate the results of this procedure into a comparison of datasets, derived using four distinct methods, to identify genes regulated directly or indirectly by ETT. We conclude from our combined analyses that PMEIs are likely to be key actors that mediate the regulation of gynecium development by ETT, while ETT may simultaneously regulate PMEs to prevent exaggerated developmental effects from the regulation of PMEIs. We also postulate the existence of one or more rapidly-acting intermediate factors in the transcriptional regulation of PMEs and PMEIs by ETT.
PMID: 32498600
J Genet Eng Biotechnol , 2020 Jul , V18 (1) : P31 doi: 10.1186/s43141-020-00047-5
Genes, proteins and other networks regulating somatic embryogenesis in plants.
Department of Botany, Jamia Hamdard (Hamdard University), New Delhi, 110062, India.; Department of Botany, Jamia Hamdard (Hamdard University), New Delhi, 110062, India. amujib3@yahoo.co.in.
BACKGROUND: Somatic embryogenesis (SE) is an intricate molecular and biochemical process principally based on cellular totipotency and a model in studying plant development. In this unique embryo-forming process, the vegetative cells acquire embryogenic competence under cellular stress conditions. The stress caused by plant growth regulators (PGRs), nutrient, oxygenic, or other signaling elements makes cellular reprogramming and transforms vegetative cells into embryos through activation/deactivation of a myriad of genes and transcriptional networks. Hundreds of genes have been directly linked to zygotic and somatic embryogeneses; some of them like SOMATIC EMBRYOGENESIS LIKE RECEPTOR KINASE (SERK), LEAFY COTYLEDON (LEC), BABYBOOM (BBM), and AGAMOUS-LIKE 15 (AGL15) are very important and are part of molecular network. MAIN TEXT (OBSERVATION): This article reviews various genes/orthologs isolated from different plants; encoded proteins and their possible role in regulating somatic embryogenesis of plants have been discussed. The role of SERK in regulating embryogenesis is also summarized. Different SE-related proteins identified through LC-MS at various stages of embryogenesis are also described; a few proteins like 14-3-3, chitinase, and LEA are used as potential SE markers. These networks are interconnected in a complicated manner, posing challenges for their complete elucidation. CONCLUSIONS: The various gene networks and factors controlling somatic embryogenesis have been discussed and presented. The roles of stress, PGRs, and other signaling elements have been discussed. In the last two-to-three decades' progress, the challenges ahead and its future applications in various fields of research have been highlighted. The review also presents the need of high throughput, innovative techniques, and sensitive instruments in unraveling the mystery of SE.
PMID: 32661633