Nat Commun , IF:14.919 , 2021 Sep , V12 (1) : P5437 doi: 10.1038/s41467-021-25250-x
Local auxin biosynthesis acts downstream of brassinosteroids to trigger root foraging for nitrogen.
Molecular Plant Nutrition, Dept. Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Stadt Seeland, OT Gatersleben, Germany.; Molecular Plant Nutrition, Dept. Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Stadt Seeland, OT Gatersleben, Germany. vonwiren@ipk-gatersleben.de.
Lateral roots (LRs) dominate the overall root surface of adult plants and are crucial for soil exploration and nutrient acquisition. When grown under mild nitrogen (N) deficiency, flowering plants develop longer LRs to enhance nutrient acquisition. This response is partly mediated by brassinosteroids (BR) and yet unknown mechanisms. Here, we show that local auxin biosynthesis modulates LR elongation while allelic coding variants of YUCCA8 determine the extent of elongation under N deficiency. By up-regulating the expression of YUCCA8/3/5/7 and of Tryptophan Aminotransferase of Arabidopsis 1 (TAA1) under mild N deficiency auxin accumulation increases in LR tips. We further demonstrate that N-dependent auxin biosynthesis in LRs acts epistatic to and downstream of a canonical BR signaling cascade. The uncovered BR-auxin hormonal module and its allelic variants emphasize the importance of fine-tuning hormonal crosstalk to boost adaptive root responses to N availability and offer a path to improve soil exploration by expanded root systems in plants.
PMID: 34521826
Plant Cell , IF:11.277 , 2021 Sep , V33 (9) : P3120-3133 doi: 10.1093/plcell/koab175
AUXIN RESPONSE FACTORS 6 and 17 control the flag leaf angle in rice by regulating secondary cell wall biosynthesis of lamina joints.
Joint International Research Laboratory of Metabolic & Developmental Sciences, State Key Laboratory of Hybrid Rice, SJTU-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.; School of Biosciences, University of Melbourne, Parkville VIC 3010, Melbourne, Australia.; Department of Plant & Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark.; School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia.; Future Food Beacon and School of Biosciences, University of Nottingham, LE12 5RD, UK.; Copenhagen Plant Science Center, University of Copenhagen, 1871, Frederiksberg C, Denmark.
Flag leaf angle impacts the photosynthetic capacity of densely grown plants and is thus an important agronomic breeding trait for crop architecture and yield. The hormone auxin plays a key role in regulating this trait, yet the underlying molecular and cellular mechanisms remain unclear. Here, we report that two rice (Oryza sativa) auxin response factors (ARFs), OsARF6 and OsARF17, which are highly expressed in lamina joint tissues, control flag leaf angle in response to auxin. Loss-of-function double osarf6 osarf17 mutants displayed reduced secondary cell wall levels of lamina joint sclerenchymatous cells (Scs), resulting in an exaggerated flag leaf angle and decreased grain yield under dense planting conditions. Mechanical measurements indicated that the mutant lamina joint tissues were too weak to support the weight of the flag leaf blade, resembling the phenotype of the rice increased leaf angle1 (ila1) mutant. We demonstrate that OsARF6 and OsARF17 directly bind to the ILA1 promoter independently and synergistically to activate its expression. In addition, auxin-induced ILA1 expression was dependent on OsARF6 and OsARF17. Collectively, our study reveals a mechanism that integrates auxin signaling with the secondary cell wall composition to determine flag leaf angle, providing breeding targets in rice, and potentially other cereals, for this key trait.
PMID: 34245297
Plant Cell , IF:11.277 , 2021 Sep , V33 (9) : P2981-3003 doi: 10.1093/plcell/koab183
GmPIN-dependent polar auxin transport is involved in soybean nodule development.
College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.; Haixia Institute of Science and Technology, Horticultural Plant Biology and Metabolomics Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.; College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.; Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.; State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.; State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.; Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria.; Department of Experimental Plant Biology, Faculty of Science, Charles University, Vinicna 5, 128 43 Prague 2, Czech Republic.; The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojova 263, 165 02 Prague 6, Czech Republic.
To overcome nitrogen deficiency, legume roots establish symbiotic interactions with nitrogen-fixing rhizobia that are fostered in specialized organs (nodules). Similar to other organs, nodule formation is determined by a local maximum of the phytohormone auxin at the primordium site. However, how auxin regulates nodule development remains poorly understood. Here, we found that in soybean, (Glycine max), dynamic auxin transport driven by PIN-FORMED (PIN) transporter GmPIN1 is involved in nodule primordium formation. GmPIN1 was specifically expressed in nodule primordium cells and GmPIN1 was polarly localized in these cells. Two nodulation regulators, (iso)flavonoids trigger expanded distribution of GmPIN1b to root cortical cells, and cytokinin rearranges GmPIN1b polarity. Gmpin1abc triple mutants generated with CRISPR-Cas9 showed the impaired establishment of auxin maxima in nodule meristems and aberrant divisions in the nodule primordium cells. Moreover, overexpression of GmPIN1 suppressed nodule primordium initiation. GmPIN9d, an ortholog of Arabidopsis thaliana PIN2, acts together with GmPIN1 later in nodule development to acropetally transport auxin in vascular bundles, fine-tuning the auxin supply for nodule enlargement. Our findings reveal how PIN-dependent auxin transport modulates different aspects of soybean nodule development and suggest that the establishment of auxin gradient is a prerequisite for the proper interaction between legumes and rhizobia.
PMID: 34240197
Proc Natl Acad Sci U S A , IF:11.205 , 2021 Sep , V118 (37) doi: 10.1073/pnas.2106961118
Perturbations in plant energy homeostasis prime lateral root initiation via SnRK1-bZIP63-ARF19 signaling.
Department of Pharmaceutical Biology, Julius-von-Sachs-Institute, Biocenter, Julius-Maximilians Universitat Wurzburg, Wurzburg 97082, Germany.; Department of Pharmaceutical Biology, Julius-von-Sachs-Institute, Biocenter, Julius-Maximilians Universitat Wurzburg, Wurzburg 97082, Germany; christoph.weiste@uni-wuerzburg.de wolfgang.droege-laser@uni-wuerzburg.de.; Umea Plant Science Center, Department of Plant Physiology, Umea University, SE-901 87 Umea, Sweden.; Department of Metabolic networks, Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.; Department of Biology, Stanford University, Stanford, CA 94305.; Department of Biochemistry and Cell Biology, University of Vienna, 1030 Vienna, Austria.; Department of Molecular Systems Biology, University of Vienna, 1030 Vienna, Austria.; Institute for Molecular Plant Physiology and Biophysics, University of Wurzburg, D-97082 Wurzburg, Germany.; Laboratory of Molecular Plant Biology, Department of Biology, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium.; KU Leuven Plant Institute (LPI), 3001 Heverlee-Leuven, Belgium.
Plants adjust their energy metabolism to continuous environmental fluctuations, resulting in a tremendous plasticity in their architecture. The regulatory circuits involved, however, remain largely unresolved. In Arabidopsis, moderate perturbations in photosynthetic activity, administered by short-term low light exposure or unexpected darkness, lead to increased lateral root (LR) initiation. Consistent with expression of low-energy markers, these treatments alter energy homeostasis and reduce sugar availability in roots. Here, we demonstrate that the LR response requires the metabolic stress sensor kinase Snf1-RELATED-KINASE1 (SnRK1), which phosphorylates the transcription factor BASIC LEUCINE ZIPPER63 (bZIP63) that directly binds and activates the promoter of AUXIN RESPONSE FACTOR19 (ARF19), a key regulator of LR initiation. Consistently, starvation-induced ARF19 transcription is impaired in bzip63 mutants. This study highlights a positive developmental function of SnRK1. During energy limitation, LRs are initiated and primed for outgrowth upon recovery. Hence, this study provides mechanistic insights into how energy shapes the agronomically important root system.
PMID: 34504003
Curr Biol , IF:10.834 , 2021 Sep , V31 (17) : P3834-3847.e5 doi: 10.1016/j.cub.2021.06.055
Periodic root branching is influenced by light through an HY1-HY5-auxin pathway.
College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China; Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, B-9052 Ghent, Belgium; VIB-UGent Center for Plant Systems Biology, Technologiepark 71, B-9052 Ghent, Belgium.; Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, China.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, B-9052 Ghent, Belgium; VIB-UGent Center for Plant Systems Biology, Technologiepark 71, B-9052 Ghent, Belgium; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River and State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River and State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, B-9052 Ghent, Belgium; VIB-UGent Center for Plant Systems Biology, Technologiepark 71, B-9052 Ghent, Belgium.; Laboratory of Medicinal Plant, Institute of Basic Medical Sciences, School of Basic Medicine, Biomedical Research Institute, Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, China.; School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China.; College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: wbshenh@njau.edu.cn.; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River and State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: wexua@njau.edu.cn.
The spacing of lateral roots (LRs) along the main root in plants is driven by an oscillatory signal, often referred to as the "root clock" that represents a pre-patterning mechanism that can be influenced by environmental signals. Light is an important environmental factor that has been previously reported to be capable of modulating the root clock, although the effect of light signaling on the LR pre-patterning has not yet been fully investigated. In this study, we reveal that light can activate the transcription of a photomorphogenic gene HY1 to maintain high frequency and amplitude of the oscillation signal, leading to the repetitive formation of pre-branch sites. By grafting and tissue-specific complementation experiments, we demonstrated that HY1 generated in the shoot or locally in xylem pole pericycle cells was sufficient to regulate LR branching. We further found that HY1 can induce the expression of HY5 and its homolog HYH, and act as a signalosome to modulate the intracellular localization and expression of auxin transporters, in turn promoting auxin accumulation in the oscillation zone to stimulate LR branching. These fundamental mechanistic insights improve our understanding of the molecular basis of light-controlled LR formation and provide a genetic interconnection between shoot- and root-derived signals in regulating periodic LR branching.
PMID: 34283998
New Phytol , IF:10.151 , 2021 Sep doi: 10.1111/nph.17719
HOMEOBOX PROTEIN 24 mediates the conversion of indole-3-butyric acid to indole-3-acetic acid to promote root hair elongation.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
Indole-3-acetic acid (IAA) is a predominant form of active auxin in plants. In addition to de novo biosynthesis and release from its conjugate forms, IAA can be converted from its precursor indole-3-butyric acid (IBA). The IBA-derived IAA may help drive root hair elongation in Arabidopsis thaliana seedlings, but how the IBA-to-IAA conversion is regulated and affects IAA function requires further investigation. In this study, HOMEOBOX PROTEIN 24 (HB24), a transcription factor in the zinc finger-homeodomain family (ZF-HD family) of proteins, was identified. With loss of HB24 function, defective growth occurred in root hairs. INDOLE-3-BUTYRIC ACID RESPONSE 1 (IBR1), which encodes an enzyme involved in the IBA-to-IAA conversion, was identified as a direct target of HB24 for the control of root hair elongation. The exogenous IAA or auxin analogue 1-naphthalene acetic acid (NAA) both rescued the root hair growth phenotype of hb24 mutants, but IBA did not, suggesting a role for HB24 in the IBA-to-IAA conversion. Therefore, HB24 participates in root hair elongation by upregulating the expression of IBR1 and subsequently promoting the IBA-to-IAA conversion. Moreover, IAA also elevated the expression of HB24, suggesting a feedback loop is involved in IBA-to-IAA conversion-mediated root hair elongation.
PMID: 34480752
New Phytol , IF:10.151 , 2021 Oct , V232 (2) : P642-654 doi: 10.1111/nph.17633
Broadening the roles of UDP-glycosyltransferases in auxin homeostasis and plant development.
Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea, SE-901 83, Sweden.
The levels of the important plant growth regulator indole-3-acetic acid (IAA) are tightly controlled within plant tissues to spatiotemporally orchestrate concentration gradients that drive plant growth and development. Metabolic inactivation of bioactive IAA is known to participate in the modulation of IAA maxima and minima. IAA can be irreversibly inactivated by oxidation and conjugation to aspartate and glutamate. Usually overlooked because of its reversible nature, the most abundant inactive IAA form is the IAA-glucose (IAA-glc) conjugate. Glycosylation of IAA in Arabidopsis thaliana is reported to be carried out by UDP-glycosyltransferase 84B1 (UGT84B1), while UGT74D1 has been implicated in the glycosylation of the irreversibly formed IAA catabolite oxIAA. Here we demonstrated that both UGT84B1 and UGT74D1 modulate IAA levels throughout plant development by dual IAA and oxIAA glycosylation. Moreover, we identified a novel UGT subfamily whose members redundantly mediate the glycosylation of oxIAA and modulate skotomorphogenic growth.
PMID: 34289137
New Phytol , IF:10.151 , 2021 Oct , V232 (2) : P510-522 doi: 10.1111/nph.17617
PIN-mediated polar auxin transport regulations in plant tropic responses.
Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria.; Research Center for Plant Functional Genes and Tissue Culture Technology, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China.; Department of Biotechnology, Taif University, PO Box 11099, Taif, 21944, Kingdom of Saudi Arabia.
Tropisms, growth responses to environmental stimuli such as light or gravity, are spectacular examples of adaptive plant development. The plant hormone auxin serves as a major coordinative signal. The PIN auxin exporters, through their dynamic polar subcellular localizations, redirect auxin fluxes in response to environmental stimuli and the resulting auxin gradients across organs underlie differential cell elongation and bending. In this review, we discuss recent advances concerning regulations of PIN polarity during tropisms, focusing on PIN phosphorylation and trafficking. We also cover how environmental cues regulate PIN actions during tropisms, as well as the crucial role of auxin feedback on PIN polarity during bending termination. Finally, the interactions between different tropisms are reviewed to understand plant adaptive growth in the natural environment.
PMID: 34254313
New Phytol , IF:10.151 , 2021 Oct , V232 (1) : P318-331 doi: 10.1111/nph.17559
Plant parasitic cyst nematodes redirect host indole metabolism via NADPH oxidase-mediated ROS to promote infection.
Rheinische Friedrich-Wilhelms-University of Bonn, INRES - Molecular Phytomedicine, Karlrobert-Kreiten-Strasse 13, Bonn, D-53115, Germany.; Department of Plant Pathology, Faculty of Agriculture, Hajee Mohammad Danesh Science and Technology University, Dinajpur, 5200, Bangladesh.; Department of Plant Breeding, Institute of Crop Science and Resource Conservation, University of Bonn, Bonn, D-53115, Germany.; Department of Entomology and Nematology, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA.; Department of Botany, Institute of Biology, Warsaw University of Life Sciences (SGGW), Warsaw, PL-02-787, Poland.; Research Group Plant Defense Physiology, Max Plank Institute for Chemical Ecology, Hans-Knoll-Strasse 8, Jena, D-07745, Germany.; Department Biotechnology, Research Group Epigenetics & Defence, Coupure links 653, Gent, B-9000, Belgium.
Reactive oxygen species (ROS) generated in response to infections often activate immune responses in eukaryotes including plants. In plants, ROS are primarily produced by plasma membrane-bound NADPH oxidases called respiratory burst oxidase homologue (Rboh). Surprisingly, Rbohs can also promote the infection of plants by certain pathogens, including plant parasitic cyst nematodes. The Arabidopsis genome contains 10 Rboh genes (RbohA-RbohJ). Previously, we showed that cyst nematode infection causes a localised ROS burst in roots, mediated primarily by RbohD and RbohF. We also found that plants deficient in RbohD and RbohF (rbohD/F) exhibit strongly decreased susceptibility to cyst nematodes, suggesting that Rboh-mediated ROS plays a role in promoting infection. However, little information is known of the mechanism by which Rbohs promote cyst nematode infection. Here, using detailed genetic and biochemical analyses, we identified WALLS ARE THIN1 (WAT1), an auxin transporter, as a downstream target of Rboh-mediated ROS during parasitic infections. We found that WAT1 is required to modulate the host's indole metabolism, including indole-3-acetic acid levels, in infected cells and that this reprogramming is necessary for successful establishment of the parasite. In conclusion, this work clarifies a unique mechanism that enables cyst nematodes to use the host's ROS for their own benefit.
PMID: 34133755
Plant Biotechnol J , IF:9.803 , 2021 Sep doi: 10.1111/pbi.13704
Modified expression of TaCYP78A5 enhances grain weight with yield potential by accumulating auxin in wheat (Triticum aestivum L.).
College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China.; State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A & F University, Yangling, Shaanxi, China.; National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China.; National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research, Huazhong Agricultural University, Wuhan, China.
Increasing grain yield has always been the primary goal of crop breeding. KLUH/CYP78A5 has been shown to affect seed size in several plant species, but the relevant molecular mechanism is still unclear and there are no reports of this gene contributing to yield. Here, we demonstrate that modified expression of TaCYP78A5 can enhance wheat grain weight and grain yield per plant by accumulating auxin. TaCYP78A5 is highly expressed in maternal tissues, including ovary and seed coat during wheat development. The constitutive overexpression of TaCYP78A5 leads to significantly increased seed size and weight but not grain yield per plant due to the strengthening of apical dominance. However, localized overexpression of TaCYP78A5 in maternal integument enhances grain weight and grain yield per plant by 4.3%-18.8% and 9.6%-14.7%, respectively, in field trials. Transcriptome and hormone metabolome analyses reveal that TaCYP78A5 participates in auxin synthesis pathway and promotes auxin accumulation and cell wall remodelling in ovary. Phenotype investigation and cytological observation show that localized overexpression of TaCYP78A5 in ovary results in delayed flowering and prolonged proliferation of maternal integument cells, which promote grain enlargement. Moreover, naturally occurring variations in the promoter of TaCYP78A5-2A contribute to thousand-grain weight (TGW) and grain yield per plant of wheat;TaCYP78A5-2A haplotype Ap-HapII with higher activity is favourable for improving grain weight and grain yield per plant and has been positively selected in wheat breeding. Then, a functional marker of TaCYP78A5 haplotype Ap-HapII is developed for marker-assisted selection in wheat grain and yield improvement.
PMID: 34510688
EMBO Rep , IF:8.807 , 2021 Sep , V22 (9) : Pe51813 doi: 10.15252/embr.202051813
Nitrate triggered phosphoproteome changes and a PIN2 phosphosite modulating root system architecture.
Departamento de Genetica Molecular y Microbiologia, Pontificia Universidad Catolica de Chile, Santiago, Chile.; FONDAP Center for Genome Regulation, ANID - Millennium Science Initiative Program - Millennium Institute for Integrative Biology (iBio), Santiago, Chile.; Departamento de Fruticultura y Enologia, Pontificia Universidad Catolica de Chile, Santiago, Chile.; Cell and Developmental Biology, University of California San Diego. San Diego, CA, USA.; Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria.; Bioresources Unit, Center for Health & Bioresources, AIT Austrian Institute of Technology GmbH, Tulln, Austria.
Nitrate commands genome-wide gene expression changes that impact metabolism, physiology, plant growth, and development. In an effort to identify new components involved in nitrate responses in plants, we analyze the Arabidopsis thaliana root phosphoproteome in response to nitrate treatments via liquid chromatography coupled to tandem mass spectrometry. 176 phosphoproteins show significant changes at 5 or 20 min after nitrate treatments. Proteins identified by 5 min include signaling components such as kinases or transcription factors. In contrast, by 20 min, proteins identified were associated with transporter activity or hormone metabolism functions, among others. The phosphorylation profile of NITRATE TRANSPORTER 1.1 (NRT1.1) mutant plants was significantly altered as compared to wild-type plants, confirming its key role in nitrate signaling pathways that involves phosphorylation changes. Integrative bioinformatics analysis highlights auxin transport as an important mechanism modulated by nitrate signaling at the post-translational level. We validated a new phosphorylation site in PIN2 and provide evidence that it functions in primary and lateral root growth responses to nitrate.
PMID: 34357701
Sci Total Environ , IF:7.963 , 2021 Sep , V788 : P147866 doi: 10.1016/j.scitotenv.2021.147866
Phytotoxicity of the chiral herbicide dichlorprop: Cross-talk between nitric oxide, reactive oxygen species and phytohormones.
College of Science and Technology, Ningbo University, Cixi 315302, China.; MOE Key Laboratory of Environmental Remediation & Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: wenyuezhong@zju.edu.cn.
Nitric oxide (NO), reactive oxygen species (ROS), and phytohormones in plants often initiate responses to sources of abiotic stress. However, we have a poor understanding of the cross-talk between NO, ROS, and phytohormones during exogenous chiral auxin-induced phytotoxicity. In this study, the toxicity of the chiral synthetic auxin herbicide dichlorprop (DCPP) to Arabidopsis thaliana, as well as the mutual regulation of NO, hydrogen peroxide (H2O2), superoxide anion (O2(.-)), and phytohormones at the enantiomeric level was investigated. The ROS production exhibited an enantioselective manner, further, that was positively correlated with the change of the morphological indicators. This confirmed that ROS played an important role in the enantioselective effect of DCPP. The distribution of ROS and NO was partially overlapped, indicating that the production of NO may be affected by ROS, and also related to the degree of plant damage. In terms of phytohormones, the level of salicylic acid (SA), jasmonic acid (JA), and abscisic acid (ABA) in the whole plant increased as the (R)-DCPP concentration applied increased, however, the trend has changed, when the data of leaves and roots was discussed separately. The results revealed that the redistribution of phytohormones may exist between leaves and roots, caused by the joint action of ROS and NO. The differences in the biological activity identified between the two enantiomers in this study enhance our understanding of the toxicity mechanism of exogenous auxin via their effects on phytohormones.
PMID: 34134377
Sci Total Environ , IF:7.963 , 2021 Sep , V788 : P147735 doi: 10.1016/j.scitotenv.2021.147735
Mechanisms of the enantioselective effects of phenoxyalkanoic acid herbicides DCPP and MCPP.
Institute of Nuclear Agricultural Sciences, Key laboratory of Nuclear Agricultural Sciences of Ministry of Agriculture of PRC and Zhejiang Province, Zhejiang University, Hangzhou 310058, China.; Department of Applied Bioscience, College of agriculture and biotechnology, Zhejiang University, Hangzhou 310029, China.; Hangzhou Botanical Garden, No.1, Taoyuan, Xihu District, Hangzhou 310012, China.; Institute of Nuclear Agricultural Sciences, Key laboratory of Nuclear Agricultural Sciences of Ministry of Agriculture of PRC and Zhejiang Province, Zhejiang University, Hangzhou 310058, China. Electronic address: qfye@zju.edu.cn.; Department of Environmental Sciences, University of California, Riverside, CA 92521, USA.
Phenoxyalkanoic acids (PAAs), synthetic indole-3-acetic acid (IAA) auxin mimics, are widely used as herbicides. Many PAAs are chiral molecules and show strong enantioselectivity in their herbicidal activity; however, there is a lack of understanding of mechanisms driving enantioselectivity. This study aimed to obtain a mechanistic understanding of PAA enantioselectivity using dichlorprop and mecoprop as model PAA compounds. Molecular docking, in vitro (3)H-IAA binding assay, and surface plasmon resonance analysis showed that the R enantiomer was preferentially combined with TIR1-IAA7 (Transport Inhibitor Response1- Auxin-Responsive Protein IAA7) than the S enantiomer. In vivo tracking using (14)C-PAAs showed a greater absorption of the R enantiomer by Arabidopsis thaliana, and further comparatively enhanced translocation of the R enantiomer to the nucleus where the auxin co-receptor is located. These observations imply that TIR1-IAA7 is a prior target for DCPP and MCPP, and that PAA enantioselectivity occurs because the R enantiomer has a stronger binding affinity for TIR1-IAA7 as well as a greater plant absorption and translocation capability than the S enantiomer. The improved understanding of PAA enantioselectivity is of great significance, as the knowledge may be used to design "green" molecules, such as R enantiomer enriched products, leading to improved plant management and environmental sustainability.
PMID: 34029804
Sci Total Environ , IF:7.963 , 2021 Sep , V787 : P147510 doi: 10.1016/j.scitotenv.2021.147510
Insights into the mechanism of multi-walled carbon nanotubes phytotoxicity in Arabidopsis through transcriptome and m6A methylome analysis.
Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China.; Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China.; College of Agronomy, Hunan Agricultural University, Changsha, Hunan 410128, China; Crop Gene Engineering Key Laboratory of Hunan Province, Changsha, Hunan, 410128, China.; College of Agronomy, Hunan Agricultural University, Changsha, Hunan 410128, China; Crop Gene Engineering Key Laboratory of Hunan Province, Changsha, Hunan, 410128, China. Electronic address: xiongene@hunau.edu.cn.; Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China. Electronic address: sujianguang@caas.cn.; National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543, Singapore. Electronic address: anyansci@gmail.com.
With the increasing production and wide application of carbon nanotubes (CNTs), they are inevitably released into the natural environment and ecosystems, where plants are the main primary producers. Hence, it is imperative to understand the toxic effects of CNTs on plants. The molecular mechanisms underlying the toxic effects of CNTs on plants are still unclear. Therefore, in the present study, we investigated the effects of high concentrations of multi-walled CNTs (MWCNTs) on Arabidopsis. Root elongation and leaf development were severely inhibited after MWCNT exposure. Excess production of H2O2, O2(-), and malondialdehyde was observed, indicating that MWCNTs induced oxidative stress. The antioxidant system was activated to counter MWCNTs-induced oxidative stress. Combinatorial transcriptome and m6A methylome analysis revealed that MWCNTs suppressed auxin signaling and photosynthesis. Reactive oxygen species metabolism, toxin metabolism, and plant responses to pathogens were enhanced to cope with the phytotoxicity of MWCNTs. Our results provide new insights into the molecular mechanisms of CNT phytotoxicity and plant defense responses to CNTs.
PMID: 33991908
Curr Opin Plant Biol , IF:7.834 , 2021 Sep , V65 : P102111 doi: 10.1016/j.pbi.2021.102111
Hormonal control of cell identity and growth in the shoot apical meristem.
College of Agriculture, South China Agricultural University, 510642, Guangzhou, China; Guangdong Laboratory for Lingnan Modern Agriculture, 510642, Guangzhou, China; Laboratoire Reproduction et Developpement des Plantes, Univ Lyon, ENS de Lyon, CNRS, INRAE, F-69342, Lyon, France.; Laboratoire Reproduction et Developpement des Plantes, Univ Lyon, ENS de Lyon, CNRS, INRAE, F-69342, Lyon, France. Electronic address: teva.vernoux@ens-lyon.fr.
How cells acquire their identities and grow coordinately within a tissue is a fundamental question to understand plant development. In angiosperms, the shoot apical meristem (SAM) is a multicellular tissue containing a stem cell niche, which activity allows for a dynamic equilibrium between maintenance of stem cells and production of differentiated cells that are incorporated in new aerial tissues and lateral organs produced in the SAM. Plant hormones are small-molecule signals controlling many aspects of plant development and physiology. Several hormones are essential regulators of SAM activities. This review highlights current advances that are starting to decipher the complex mechanisms underlying the hormonal control of cell identity and growth in the SAM.
PMID: 34543915
BMC Biol , IF:7.431 , 2021 Sep , V19 (1) : P213 doi: 10.1186/s12915-021-01143-9
Control of vein-forming, striped gene expression by auxin signaling.
Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada.; Present Address - Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA, 90095, USA.; Present Address - Department of Biology, University of British Columbia, Kelowna, BC, V1V 1V7, Canada.; Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada. enrico.scarpella@ualberta.ca.
BACKGROUND: Activation of gene expression in striped domains is a key building block of biological patterning, from the recursive formation of veins in plant leaves to that of ribs and vertebrae in our bodies. In animals, gene expression is activated in striped domains by the differential affinity of broadly expressed transcription factors for their target genes and the combinatorial interaction between such target genes. In plants, how gene expression is activated in striped domains is instead unknown. We address this question for the broadly expressed MONOPTEROS (MP) transcription factor and its target gene ARABIDOPSIS THALIANA HOMEOBOX FACTOR8 (ATHB8). RESULTS: We find that ATHB8 promotes vein formation and that such vein-forming function depends on both levels of ATHB8 expression and width of ATHB8 expression domains. We further find that ATHB8 expression is activated in striped domains by a combination of (1) activation of ATHB8 expression through binding of peak levels of MP to a low-affinity MP-binding site in the ATHB8 promoter and (2) repression of ATHB8 expression by MP target genes of the AUXIN/INDOLE-3-ACETIC-ACID-INDUCIBLE family. CONCLUSIONS: Our findings suggest that a common regulatory logic controls activation of gene expression in striped domains in both plants and animals despite the independent evolution of their multicellularity.
PMID: 34556094
Plant Cell Environ , IF:7.228 , 2021 Oct , V44 (10) : P3257-3272 doi: 10.1111/pce.14141
Jujube witches' broom phytoplasma effectors SJP1 and SJP2 induce lateral bud outgrowth by repressing the ZjBRC1-controlled auxin efflux channel.
College of Horticulture, Anhui Agricultural University, Hefei City, China.; Horticulture Research Institute, Anhui Academy of Agricultural Sciences, Hefei City, China.; State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei City, China.
Comprehensively controlling phytoplasma-associated jujube witches' broom (JWB) disease is extremely challenging for the jujube industry. Although the pathogenesis of phytoplasma disease has been highlighted in many plant species, the release of lateral buds from dormancy under JWB phytoplasma infection has not been characterized in woody perennial jujube. Here, two 16SrV-B group phytoplasma effectors, SJP1 and SJP2, were experimentally determined to induce witches' broom with increased lateral branches. In vivo interaction and subcellular localization analyses showed that both SJP1 and SJP2 were translocated from the cytoplasm to the nucleus to target the CYC/TB1-TCP transcription factor ZjBRC1. The N- and C-terminal coiled-coil domains of SJP1 and SJP2 were required for the TCP-binding ability. ZjBRC1 bound directly to the auxin efflux carrier ZjPIN1c/3 promoters and down-regulated their expression to promote the accumulation of endogenous auxin indole-3-acetic acid in jujube calli. Furthermore, JWB phytoplasma infection suppressed ZjBRC1 accumulation and induced ZjPIN1c/3 expression to stimulate lateral bud outgrowth. Therefore, SJP1 and SJP2 stimulate lateral bud outgrowth, at least partly, by repressing the ZjBRC1-controlled auxin efflux channel in jujube, representing a potential strategy for comprehensive phytoplasma-associated disease control and a resource for gene editing breeding to create new cultivars with varying degrees of shoot branching.
PMID: 34189742
Plant Cell Environ , IF:7.228 , 2021 Oct , V44 (10) : P3302-3321 doi: 10.1111/pce.14133
Long noncoding RNA lncRNA354 functions as a competing endogenous RNA of miR160b to regulate ARF genes in response to salt stress in upland cotton.
State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, China.
Long non-coding RNAs (lncRNAs) play important roles in response to biotic and abiotic stress through acting as competing endogenous RNAs (ceRNAs) to decoy mature miRNAs. However, whether this mechanism is involved in cotton salt stress response remains unknown. We report the characterization of an endogenous lncRNA, lncRNA354, whose expression was reduced in salt-treated cotton and was localized at the nucleus and cytoplasm. Using endogenous target mimic (eTM) analysis, we predicted that lncRNA354 had a potential binding site for miR160b. Transient expression in tobacco demonstrated that lncRNA354 was a miR160b eTM and attenuated miR160b suppression of its target genes, including auxin response factors (ARFs). Silencing or overexpressing lncRNA354 affected the expression of miR160b and target ARFs. Silencing lncRNA354 and targets GhARF17/18 resulted in taller cotton plants and enhanced the resistant to salt stress. Overexpression of lncRNA354 and targets GhARF17/18 in Arabidopsis led to dwarf plants, decreased root dry weight and reduced salt tolerance. Our results show that the lncRNA354-miR160b effect on GhARF17/18 expression may modulate auxin signalling and thus affect growth. These results also shed new light on a mechanism of lncRNA-associated responses to salt stress.
PMID: 34164822
J Integr Plant Biol , IF:7.061 , 2021 Sep doi: 10.1111/jipb.13171
Clathrin light chains regulate hypocotyl elongation by affecting the polarization of the auxin transporter PIN3 in Arabidopsis.
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.; College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China.; College of Life Sciences, Shaoxing University, Shaoxing, 312000, China.
PIN-FORMED (PIN)-dependent directional auxin transport is crucial for plant development. Although the redistribution of auxin mediated by the polarization of PIN3 plays key roles in modulating hypocotyl cell expansion, how PIN3 becomes repolarized to the proper sites within hypocotyl cells is poorly understood. We previously generated the clathrin light chain clc2-1 clc3-1 double mutant in Arabidopsis thaliana and found that it has an elongated hypocotyl phenotype compared to the wild type. Here, we performed genetic, cell biology, and pharmacological analyses combined with live-cell imaging to elucidate the molecular mechanism underlying the role of clathrin light chains in hypocotyl elongation. Our analyses indicated that the defects of the double mutant enhanced auxin maxima in epidermal cells, thus, promoting hypocotyl elongation. PIN3 relocated to the lateral sides of hypocotyl endodermal cells in clc2-1 clc3-1 mutants to redirect auxin toward the epidermal cell layers. Moreover, the loss of function of PIN3 largely suppressed the long hypocotyl phenotype of the clc2-1 clc3-1 double mutant, as did treatment with auxin transport inhibitors. Based on these data, we propose that clathrin modulates PIN3 abundance and polarity to direct auxin flux and inhibit cell elongation in the hypocotyl, providing novel insights into the regulation of hypocotyl elongation. This article is protected by copyright. All rights reserved.
PMID: 34478221
Front Nutr , IF:6.576 , 2021 , V8 : P703293 doi: 10.3389/fnut.2021.703293
Wheat-Fusarium graminearum Interactions Under Sitobion avenae Influence: From Nutrients and Hormone Signals.
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, China.; Shaanxi Key Laboratory of Chinese Jujube, College of Life Science, Yan'an University, Yan'an, China.; Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON, Canada.
The English grain aphid Sitobion avenae and phytopathogen Fusarium graminearum are wheat spike colonizers. "Synergistic" effects of the coexistence of S. avenae and F. graminearum on the wheat spikes have been shown in agroecosystems. To develop genetic resistance in diverse wheat cultivars, an important question is how to discover wheat-F. graminearum interactions under S. avenae influence. In recent decades, extensive studies have typically focused on the unraveling of more details on the relationship between wheat-aphids and wheat-pathogens that has greatly contributed to the understanding of these tripartite interactions at the ecological level. Based on the scientific production available, the working hypotheses were synthesized from the aspects of environmental nutrients, auxin production, hormone signals, and their potential roles related to the tripartite interaction S. avenae-wheat-F. graminearum. In addition, this review highlights the relevance of preexposure to the herbivore S. avenae to trigger the accumulation of mycotoxins, which stimulates the infection process of F. graminearum and epidemic of Fusarium head blight (FHB) in the agroecosystems.
PMID: 34568403
Plant J , IF:6.417 , 2021 Sep doi: 10.1111/tpj.15508
Spatiotemporal regulation of JAZ4 expression and splicing contribute to ethylene- and auxin-mediated responses in Arabidopsis roots.
Department of Plant Sciences, University of California, Davis, CA, USA.; Plant Pathology Graduate Group, University of California, Davis, CA, USA.
Jasmonic acid (JA) signaling controls several processes related to plant growth, development, and defense, which are modulated by the transcription regulator and receptor JASMONATE-ZIM DOMAIN (JAZ) proteins. We recently discovered that a member of the JAZ family, JAZ4 has a prominent function in canonical JA signaling as well as other mechanisms. Here, we discovered the existence of two naturally occurring splice variants (SVs) of JAZ4 in planta, JAZ4.1 and JAZ4.2, and employed biochemical and pharmacological approaches to determine protein stability and repression capability of these SVs within JA signaling. We then utilized quantitative and qualitative transcriptional studies to determine spatiotemporal expression and splicing patterns in vivo, which revealed developmental-, tissue-, and organ-specific regulation. Detailed phenotypic and expression analyses suggest a role of JAZ4 in ethylene (ET) and auxin signaling pathways differentially within the zones of root development in seedlings. These results support a model in which JAZ4 functions as a negative regulator of ET signaling and auxin signaling in root tissues above the apex. However, in the root apex JAZ4 functions as a positive regulator of auxin signaling possibly independently of ET. Collectively, our data provides insight into the complexity of spatiotemporal regulation of JAZ4 and how this impacts hormone signaling specificity and diversity in Arabidopsis roots.
PMID: 34562337
Plant J , IF:6.417 , 2021 Sep doi: 10.1111/tpj.15489
Molecular mechanisms and hormonal regulation underpinning morphological dormancy: a case study using Apium graveolens (Apiaceae).
Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK.; Tozer Seeds, Tozer Seeds Ltd, Cobham, KT11 3EH, UK.; Laboratory of Growth Regulators, Institute of Experimental Botany, Czech Academy of Sciences and Faculty of Science, Palacky University Olomouc, Olomouc, CZ-78371, Czech Republic.; Swiss Light Source, Paul Scherrer Institute, Villigen, CH-5232, Switzerland.
Underdeveloped (small) embryos embedded in abundant endosperm tissue, and thus having morphological dormancy (MD) or morphophysiological dormancy (MPD), are considered to be the ancestral state in seed dormancy evolution. This trait is retained in the Apiaceae family, which provides excellent model systems for investigating the underpinning mechanisms. We investigated Apium graveolens (celery) MD by combined innovative imaging and embryo growth assays with the quantification of hormone metabolism, as well as the analysis of hormone and cell-wall related gene expression. The integrated experimental results demonstrated that embryo growth occurred inside imbibed celery fruits in association with endosperm degradation, and that a critical embryo size was required for radicle emergence. The regulation of these processes depends on gene expression leading to gibberellin and indole-3-acetic acid (IAA) production by the embryo and on crosstalk between the fruit compartments. ABA degradation associated with distinct spatiotemporal patterns in ABA sensitivity control embryo growth, endosperm breakdown and radicle emergence. This complex interaction between gibberellins, IAA and ABA metabolism, and changes in the tissue-specific sensitivities to these hormones is distinct from non-MD seeds. We conclude that the embryo growth to reach the critical size and the associated endosperm breakdown inside MD fruits constitute a unique germination programme.
PMID: 34510583
Antioxidants (Basel) , IF:6.312 , 2021 Sep , V10 (9) doi: 10.3390/antiox10091494
Peroxisomal PEX7 Receptor Affects Cadmium-Induced ROS and Auxin Homeostasis in Arabidopsis Root System.
Department of Environmental Biology, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.; Department of European and Mediterranean Cultures: Architecture, Environment, and Cultural Heritage (DICEM), University of Basilicata, Via San Rocco 3, 75100 Matera, Italy.
Peroxisomes are important in plant physiological functions and stress responses. Through the production of reactive oxygen and nitrogen species (ROS and RNS), and antioxidant defense enzymes, peroxisomes control cellular redox homeostasis. Peroxin (PEX) proteins, such as PEX7 and PEX5, recognize peroxisome targeting signals (PTS1/PTS2) important for transporting proteins from cytosol to peroxisomal matrix. pex7-1 mutant displays reduced PTS2 protein import and altered peroxisomal metabolism. In this research we analyzed the role of PEX7 in the Arabidopsis thaliana root system exposed to 30 or 60 muM CdSO4. Cd uptake and translocation, indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) levels, and reactive oxygen species (ROS) and reactive nitrogen species (RNS) levels and catalase activity were analyzed in pex7-1 mutant primary and lateral roots in comparison with the wild type (wt). The peroxisomal defect due to PEX7 mutation did not reduce Cd-uptake but reduced its translocation to the shoot and the root cell peroxisomal signal detected by 8-(4-Nitrophenyl) Bodipy (N-BODIPY) probe. The trend of nitric oxide (NO) and peroxynitrite in pex7-1 roots, exposed/not exposed to Cd, was as in wt, with the higher Cd-concentration inducing higher levels of these RNS. By contrast, PEX7 mutation caused changes in Cd-induced hydrogen peroxide (H2O2) and superoxide anion (O2(-)) levels in the roots, delaying ROS-scavenging. Results show that PEX7 is involved in counteracting Cd toxicity in Arabidopsis root system by controlling ROS metabolism and affecting auxin levels. These results add further information to the important role of peroxisomes in plant responses to Cd.
PMID: 34573126
Ecotoxicol Environ Saf , IF:6.291 , 2021 Sep , V225 : P112734 doi: 10.1016/j.ecoenv.2021.112734
Overexpression of auxin response gene MdIAA24 enhanced cadmium tolerance in apple (Malus domestica).
State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A & F University, Yangling 712100, Shaanxi, China.; State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A & F University, Yangling 712100, Shaanxi, China. Electronic address: fwm64@nwsuaf.edu.cn.; State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A & F University, Yangling 712100, Shaanxi, China. Electronic address: chliu@nwafu.edu.cn.
Cadmium (Cd), a phytotoxic heavy metal accumulated in plants and fruits, has significant adverse effects on plant growth and development as well as human health. In particular, Cd pollution has become a serious agricultural issue in recent years. Apple is one of the most popular fruits consumed at the global scale. Improving apple Cd resistance via reductions in Cd absorption can benefit apple tree growth and ensure fruit safety. In this study, we determined that, under the 200 muM Cd treatment, 35S::MdIAA24 apple plants exhibited more biomass and less Cd accumulation in the tested tissues compared to wild type (WT). Furthermore, the 35S::MdIAA24 apple plants demonstrated more favorable photosynthesis characteristics, less reactive oxygen species (ROS) and a greater amount of active antioxidant enzymes under the Cd condition than WT. The expression levels of the Cd uptake genes were observed to be lower in the 35S::MdIAA24 apple plants compared with those of the WT under the Cd treatment. The results highlight the ability of the overexpression of MdIAA24 to enhance apple Cd resistance by improving antioxidant capacity and reducing Cd absorption.
PMID: 34482065
Int J Mol Sci , IF:5.923 , 2021 Sep , V22 (18) doi: 10.3390/ijms22189826
Drought and High Temperature Stress in Sorghum: Physiological, Genetic, and Molecular Insights and Breeding Approaches.
Department of Crop Physiology, Tamil Nadu Agricultural University, Madras 641 003, India.; International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502 324, India.; Institute of Field and Vegetable Crops, National Institute of the Republic of Serbia, Maxim Gorki 30, 21000 Novi Sad, Serbia.; Stress Physiology and Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110 067, India.; Plant Stress Biology, International Centre for Genetic Engineering and Biotechnology, New Delhi 110 067, India.; National Agri-Food Biotechnology Institute, Mohali 140 306, India.; Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA.
Sorghum is one of the staple crops for millions of people in Sub-Saharan Africa (SSA) and South Asia (SA). The future climate in these sorghum production regions is likely to have unexpected short or long episodes of drought and/or high temperature (HT), which can cause significant yield losses. Therefore, to achieve food and nutritional security, drought and HT stress tolerance ability in sorghum must be genetically improved. Drought tolerance mechanism, stay green, and grain yield under stress has been widely studied. However, novel traits associated with drought (restricted transpiration and root architecture) need to be explored and utilized in breeding. In sorghum, knowledge on the traits associated with HT tolerance is limited. Heat shock transcription factors, dehydrins, and genes associated with hormones such as auxin, ethylene, and abscisic acid and compatible solutes are involved in drought stress modulation. In contrast, our understanding of HT tolerance at the omic level is limited and needs attention. Breeding programs have exploited limited traits with narrow genetic and genomic resources to develop drought or heat tolerant lines. Reproductive stages of sorghum are relatively more sensitive to stress compared to vegetative stages. Therefore, breeding should incorporate appropriate pre-flowering and post-flowering tolerance in a broad genetic base population and in heterotic hybrid breeding pipelines. Currently, more than 240 QTLs are reported for drought tolerance-associated traits in sorghum prospecting discovery of trait markers. Identifying traits and better understanding of physiological and genetic mechanisms and quantification of genetic variability for these traits may enhance HT tolerance. Drought and HT tolerance can be improved by better understanding mechanisms associated with tolerance and screening large germplasm collections to identify tolerant lines and incorporation of those traits into elite breeding lines. Systems approaches help in identifying the best donors of tolerance to be incorporated in the SSA and SA sorghum breeding programs. Integrated breeding with use of high-throughput precision phenomics and genomics can deliver a range of drought and HT tolerant genotypes that can improve yield and resilience of sorghum under drought and HT stresses.
PMID: 34575989
Int J Mol Sci , IF:5.923 , 2021 Sep , V22 (18) doi: 10.3390/ijms22189768
Jasmonic Acid-Dependent MYC Transcription Factors Bind to a Tandem G-Box Motif in the YUCCA8 and YUCCA9 Promoters to Regulate Biotic Stress Responses.
Centro de Biotecnologia y Genomica de Plantas, Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentacion (INIA), Universidad Politecnica de Madrid (UPM), 28223 Pozuelo de Alarcon, Spain.; Department of Forest Genetics and Plant Physiology, Umea Plant Sciences Centre (UPSC), Swedish University of Agricultural Science, 90183 Umea, Sweden.; Institut fur Biologie, Bereich Pflanzenwissenschaften, Karl-Franzens Universitat Graz, 8010 Graz, Austria.; Departamento de Biotecnologia-Biologia Vegetal, Escuela Tecnica Superior de Ingenieria Agronomica, Alimentaria y de Biosistemas, Universidad Politecnica de Madrid (UPM), 28040 Madrid, Spain.
The indole-3-pyruvic acid pathway is the main route for auxin biosynthesis in higher plants. Tryptophan aminotransferases (TAA1/TAR) and members of the YUCCA family of flavin-containing monooxygenases catalyze the conversion of l-tryptophan via indole-3-pyruvic acid to indole-3-acetic acid (IAA). It has been described that jasmonic acid (JA) locally produced in response to mechanical wounding triggers the de novo formation of IAA through the induction of two YUCCA genes, YUC8 and YUC9. Here, we report the direct involvement of a small number of basic helix-loop-helix transcription factors of the MYC family in this process. We show that the JA-mediated regulation of the expression of the YUC8 and YUC9 genes depends on the abundance of MYC2, MYC3, and MYC4. In support of this observation, seedlings of myc knockout mutants displayed a strongly reduced response to JA-mediated IAA formation. Furthermore, transactivation assays provided experimental evidence for the binding of MYC transcription factors to a particular tandem G-box motif abundant in the promoter regions of YUC8 and YUC9, but not in the promoters of the other YUCCA isogenes. Moreover, we demonstrate that plants that constitutively overexpress YUC8 and YUC9 show less damage after spider mite infestation, thereby underlining the role of auxin in plant responses to biotic stress signals.
PMID: 34575927
Front Plant Sci , IF:5.753 , 2021 , V12 : P629776 doi: 10.3389/fpls.2021.629776
Laccase Directed Lignification Is One of the Major Processes Associated With the Defense Response Against Pythium ultimum Infection in Apple Roots.
Tree Fruit Research Laboratory, USDA-ARS, Wenatchee, WA, United States.; College of Horticulture, South China Agricultural University, Guangzhou, China.; Plant Pathology and Plant-Microbe Biology Section, Cornell University, Geneva, NY, United States.; Plant Genetic Resources Unit, USDA-ARS, Geneva, NY, United States.
Apple replant disease (ARD), incited by a pathogen complex including Pythium ultimum, causes stunted growth or death of newly planted trees at replant sites. Development and deployment of resistant or tolerant rootstocks offers a cost-effective, ecologically friendly, and durable approach for ARD management. Maximized exploitation of natural resistance requires integrated efforts to identify key regulatory mechanisms underlying resistance traits in apple. In this study, miRNA profiling and degradome sequencing identified major miRNA pathways and candidate genes using six apple rootstock genotypes with contrasting phenotypes to P. ultimum infection. The comprehensive RNA-seq dataset offered an expansive view of post-transcriptional regulation of apple root defense activation in response to infection from P. ultimum. Several pairs of miRNA families and their corresponding targets were identified for their roles in defense response in apple roots, including miR397-laccase, miR398-superoxide dismutase, miR10986-polyphenol oxidase, miR482-resistance genes, and miR160-auxin response factor. Of these families, the genotype-specific expression patterns of miR397 indicated its fundamental role in developing defense response patterns to P. ultimum infection. Combined with other identified copper proteins, the importance of cellular fortification, such as lignification of root tissues by the action of laccase, may critically contribute to genotype-specific resistance traits. Our findings suggest that quick and enhanced lignification of apple roots may significantly impede pathogen penetration and minimize the disruption of effective defense activation in roots of resistant genotypes. The identified target miRNA species and target genes consist of a valuable resource for subsequent functional analysis of their roles during interaction between apple roots and P. ultimum.
PMID: 34557205
FEBS J , IF:5.542 , 2021 Sep doi: 10.1111/febs.16210
Plant programmed cell death meets auxin signalling.
University College Dublin, School of Biology and Environmental Science, Science Centre, Belfield, Ireland.
Both auxin signalling and programmed cell death (PCD) are essential components of a normally functioning plant. Auxin underpins plant growth and development, as well as regulating plant defences against environmental stresses. PCD, a genetically controlled pathway for selective elimination of redundant, damaged, or infected cells, is also a key element of many developmental processes and stress response mechanisms in plants. An increasing body of evidence suggests that auxin signalling and PCD regulation are often connected. While generally auxin appears to suppress cell death, it has also been shown to promote PCD events, most likely via stimulation of ethylene biosynthesis. Intriguingly, certain cells undergoing PCD have also been suggested to control the distribution of auxin in plant tissues, by either releasing a burst of auxin or creating an anatomical barrier to auxin transport and distribution. These recent findings indicate novel roles of localized PCD events in the context of plant development such as control of root architecture, or tissue regeneration following injury, and suggest exciting possibilities for incorporation of this knowledge into crop improvement strategies.
PMID: 34543510
Front Mol Biosci , IF:5.246 , 2021 , V8 : P708530 doi: 10.3389/fmolb.2021.708530
A Plant Stress-Responsive Bioreporter Coupled With Transcriptomic Analysis Allows Rapid Screening for Biocontrols of Necrotrophic Fungal Pathogens.
Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Floreat, WA, Australia.; Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, St Lucia, QLD, Australia.; Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Acton, ACT, Australia.
Streptomyces are soil-borne Actinobacteria known to produce a wide range of enzymes, phytohormones, and metabolites including antifungal compounds, making these microbes fitting for use as biocontrol agents in agriculture. In this study, a plant reporter gene construct comprising the biotic stress-responsive glutathione S-transferase promoter GSTF7 linked to a luciferase output (GSTF7:luc) was used to screen a collection of Actinobacteria candidates for manipulation of plant biotic stress responses and their potential as biocontrol agents. We identified a Streptomyces isolate (KB001) as a strong candidate and demonstrated successful protection against two necrotrophic fungal pathogens, Sclerotinia sclerotiorum and Rhizoctonia solani, but not against a bacterial pathogen (Pseudomonas syringe). Treatment of Arabidopsis plants with either KB001 microbial culture or its secreted compounds induced a range of stress and defense response-related genes like pathogenesis-related (PR) and hormone signaling pathways. Global transcriptomic analysis showed that both treatments shared highly induced expression of reactive oxygen species and auxin signaling pathways at 6 and 24 h posttreatment, while some other responses were treatment specific. This study demonstrates that GSTF7 is a suitable marker for the rapid and preliminary screening of beneficial bacteria and selection of candidates with potential for application as biocontrols in agriculture, including the Streptomyces KB001 that was characterized here, and could provide protection against necrotrophic fungal pathogens.
PMID: 34540894
Biology (Basel) , IF:5.079 , 2021 Sep , V10 (9) doi: 10.3390/biology10090879
Phenotype Switching in Metal-Tolerant Bacteria Isolated from a Hyperaccumulator Plant.
Department of Biology and Biotechnology of Microorganisms, The John Paul II Catholic University of Lublin, Konstantynow St. 1 I, 20-708 Lublin, Poland.; Department of Agricultural Microbiology, Institute of Soil Science and Plant Cultivation-State Research Institute, Czartoryskich 8 St., 24-100 Pulawy, Poland.
As an adaptation to unfavorable conditions, microorganisms may represent different phenotypes. Azolla filiculoides L. is a hyperaccumulator of pollutants, but the functions of its microbiome have not been well recognized to date. We aimed to reveal the potential of the microbiome for degradation of organic compounds, as well as its potential to promote plant growth in the presence of heavy metals. We applied the Biolog(TM) Phenotypic Microarrays platform to study the potential of the microbiome for the degradation of 96 carbon compounds and stress factors and assayed the hydrolytic potential and auxin production by the microorganisms in the presence of Pb, Cd, Cr (VI), Ni, Ag, and Au. We found various phenotype changes depending on the stress factor, suggesting a possible dual function of the studied microorganisms, i.e., in bioremediation and as a biofertilizer for plant growth promotion. Delftia sp., Staphylococcus sp. and Microbacterium sp. exhibited high efficacy in metabolizing organic compounds. Delftia sp., Achromobacter sp. and Agrobacterium sp. were efficient in enzymatic responses and were characterized by metal tolerant. Since each strain exhibited individual phenotype changes due to the studied stresses, they may all be beneficial as both biofertilizers and bioremediation agents, especially when combined in one biopreparation.
PMID: 34571755
Plant Cell Physiol , IF:4.927 , 2021 Sep doi: 10.1093/pcp/pcab142
Diketopiperazine Modulates Arabidopsis Thaliana Root System Architecture by Promoting Interactions of Auxin Receptor TIR1 and IAA7/17 Proteins.
School of Life and Pharmaceutical Sciences, Key Laboratory of Tropical Biological Resources of Ministry Education, Hainan University, Haikou, 571157 China.; Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200000 China.; School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210000 China.; State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200000 China.
Plants can detect the quorum sensing (QS) signaling molecules of microorganisms, such as amino acids, fat derivatives, and diketopiperazines (DKPs), thus allowing the exchange information to promote plant growth and development. Here, we evaluated the effects of 12 synthesized DKPs on Arabidopsis thaliana roots and studied their underlying mechanisms of action. Results showed that, as QS signal molecules, the DKPs promoted lateral root development and root hair formation in Arabidopsis thaliana to differing degrees. The DKPs enhanced the polar transport of the plant hormone auxin from the shoot to root and triggered the auxin-responsive protein IAA7/17 to decrease the auxin response factor (ARF), leading to the accumulation of auxin at the root tip and accelerated root growth. In addition, the DKPs induced the development of lateral roots and root hair in the Arabidopsis thaliana root system architecture via interference with auxin receptor transporter inhibitor response protein 1 (TIR1). A series of TIR1 sites that potentially interact with DKPs were also predicted using molecular docking analysis. Mutations of these sites inhibited the phosphorylation of TIR1 after DKP treatment, thereby inhibiting lateral root formation, especially TIR1-1 site. This study identified several DKP signal molecules in the QS system that can promote the expression of auxin response factors ARF7/19 via interactions of TIR1 and IAA7/17 proteins, thus promoting plant growth and development.
PMID: 34534338
Plant Cell Physiol , IF:4.927 , 2021 Sep , V62 (4) : P708-720 doi: 10.1093/pcp/pcab028
EIN3-Mediated Ethylene Signaling Attenuates Auxin Response during Hypocotyl Thermomorphogenesis.
Department of Chemistry, Seoul National University, Seoul 08826, Korea.; Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826, Korea.
The gaseous phytohormone ethylene plays vital roles in diverse developmental and environmental adaptation processes, such as fruit ripening, seedling establishment, mechanical stress tolerance and submergence escape. It is also known that in the light, ethylene promotes hypocotyl growth by stimulating the expression of PHYTOCHROME INTERACTING FACTOR3 (PIF3) transcription factor, which triggers microtubule reorganization during hypocotyl cell elongation. In particular, ethylene has been implicated in plant responses to warm temperatures in recent years. However, it is currently unclear how ethylene signals are functionally associated with hypocotyl thermomorphogenesis at the molecular level. Here, we show that ETHYLENE-INSENSITIVE3 (EIN3)-mediated ethylene signals attenuate hypocotyl thermomorphogenesis by suppressing auxin response. At warm temperatures, when the activity of the PIF4 thermomorphogenesis promoter is prominently high, the ethylene-activated EIN3 transcription factor directly induces the transcription of ARABIDOPSIS PP2C CLADE D7 (APD7) gene encoding a protein phosphatase that inactivates the plasma membrane (PM) H+-ATPase proton pumps. In conjunction with the promotive role of the PM H+-ATPases in hypocotyl cell elongation, our observations strongly support that the EIN3-directed induction of APD7 gene is linked with the suppression of auxin-induced cell expansion, leading to the reduction in thermomorphogenic hypocotyl growth. Our data demonstrate that APD7 acts as a molecular hub that integrates ethylene and auxin signals into hypocotyl thermomorphogenesis. We propose that the ethylene-auxin signaling crosstalks via the EIN3-APD7 module facilitate the fine-tuning of hypocotyl thermomorphogenesis under natural environments, which often fluctuate in a complex manner.
PMID: 33594435
Plant Cell Physiol , IF:4.927 , 2021 Sep , V62 (4) : P610-623 doi: 10.1093/pcp/pcab014
Strigolactones and Auxin Cooperate to Regulate Maize Root Development and Response to Nitrate.
Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Viale dell'Universita 16, Legnaro 35020, Italy.; Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Universite Paris-Saclay, Versailles 78000, France.; Department of Agricultural and Food Sciences (DISTAL), University of Bologna, Viale Fanin 44, Bologna 40127, Italy.
In maize, nitrate regulates root development thanks to the coordinated action of many players. In this study, the involvement of strigolactones (SLs) and auxin as putative components of the nitrate regulation of lateral root (LR) was investigated. To this aim, the endogenous SL content of maize root in response to nitrate was assessed by liquid chromatography with tandem mass Spectrometry (LC-MS/MS) and measurements of LR density in the presence of analogues or inhibitors of auxin and SLs were performed. Furthermore, an untargeted RNA-sequencing (RNA-seq)-based approach was used to better characterize the participation of auxin and SLs to the transcriptional signature of maize root response to nitrate. Our results suggested that N deprivation induces zealactone and carlactonoic acid biosynthesis in root, to a higher extent if compared to P-deprived roots. Moreover, data on LR density led to hypothesize that the induction of LR development early occurring upon nitrate supply involves the inhibition of SL biosynthesis, but that the downstream target of SL shutdown, besides auxin, also includes additional unknown players. Furthermore, RNA-seq results provided a set of putative markers for the auxin- or SL-dependent action of nitrate, meanwhile also allowing to identify novel components of the molecular regulation of maize root response to nitrate. Globally, the existence of at least four different pathways was hypothesized: one dependent on auxin, a second one mediated by SLs, a third deriving from the SL-auxin interplay, and a last one attributable to nitrate itself through further downstream signals. Further work will be necessary to better assess the reliability of the model proposed.
PMID: 33508105
Physiol Plant , IF:4.5 , 2021 Sep doi: 10.1111/ppl.13560
Role of the KNOTTED1-LIKE HOMEOBOX protein (KD1) in regulating abscission of tomato flower pedicels at early and late stages of the process.
Department of Postharvest Science, Agricultural Research Organization (ARO), Volcani Institute, Israel.; Department of Horticulture, Neelakudi Campus, School of Life Sciences, Central University of Tamil Nadu (CUTN), Thiruvarur, India.; State Key Laboratory of Agrobiotechnology, Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, China Agricultural University, Beijing, China.; Crops Pathology and Genetic Research Unit, USDA-ARS, Davis, CA, USA.; Department of Plant Sciences, University of California at Davis, Davis, CA, USA.; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
The KNOTTED1-LIKE HOMEOBOX PROTEIN1 (KD1) gene is highly expressed in flower and leaf abscission zones (AZs), and KD1 was reported to regulate tomato flower pedicel abscission via alteration of the auxin gradient and response in the flower AZ (FAZ). The present work was aimed to further examine how KD1 regulates signaling factors and regulatory genes involved in pedicel abscission, by using silenced KD1 lines and performing a large-scale transcriptome profiling of the FAZ before and after flower removal, using a customized AZ-specific microarray. The results highlighted a differential expression of regulatory genes in the FAZ of KD1-silenced plants compared to the wild type. In the TAPG4::antisense KD1-silenced plants, KD1 gene expression decreased before flower removal, resulting in altered expression of regulatory genes, such as epigenetic modifiers, transcription factors, posttranslational regulators, and antioxidative defense factors occurring at zero time and before affecting auxin levels in the FAZ detected at 4 h after flower removal. The expression of additional regulatory genes was altered in the FAZ of KD1-silenced plants at 4-20 h after flower removal, thereby leading to an inhibited abscission phenotype, and downregulation of genes involved in abscission execution and defense processes. Our data suggest that KD1 is a master regulator of the abscission process, which promotes abscission of tomato flower pedicels. This suggestion is based on the inhibitory effect of KD1 silencing on flower pedicel abscission that operates via alteration of various regulatory pathways, which delay the competence acquisition of the FAZ cells to respond to ethylene signaling.
PMID: 34545591
Physiol Plant , IF:4.5 , 2021 Sep doi: 10.1111/ppl.13546
Role of sugar and auxin crosstalk in plant growth and development.
National Institute of Plant Genome Research, New Delhi, India.; Bhuwaneshwar Sharan Mishra, Ram Gulam Rai P. G. College Banktashiv, Affiliated to Deen Dayal Upadhyaya Gorakhpur University Gorakhpur, Deoria, Uttar Pradesh, India.
Under the natural environment, nutrient signals interact with phytohormones to coordinate and reprogram plant growth and survival. Sugars are important molecules that control almost all morphological and physiological processes in plants, ranging from seed germination to senescence. In addition to their functions as energy resources, osmoregulation, storage molecules, and structural components, sugars function as signaling molecules and interact with various plant signaling pathways, such as hormones, stress, and light to modulate growth and development according to fluctuating environmental conditions. Auxin, being an important phytohormone, is associated with almost all stages of the plant's life cycle and also plays a vital role in response to the dynamic environment for better growth and survival. In the previous years, substantial progress has been made that showed a range of common responses mediated by sugars and auxin signaling. This review discusses how sugar signaling affects auxin at various levels from its biosynthesis to perception and downstream gene activation. On the same note, the review also highlights the role of auxin signaling in fine-tuning sugar metabolism and carbon partitioning. Furthermore, we discussed the crosstalk between the two signaling machineries in the regulation of various biological processes, such as gene expression, cell cycle, development, root system architecture, and shoot growth. In conclusion, the review emphasized the role of sugar and auxin crosstalk in the regulation of several agriculturally important traits. Thus, engineering of sugar and auxin signaling pathways could potentially provide new avenues to manipulate for agricultural purposes.
PMID: 34480799
DNA Res , IF:4.458 , 2021 Sep , V28 (5) doi: 10.1093/dnares/dsab014
Transcriptomes and DNA methylomes in apomictic cells delineate nucellar embryogenesis initiation in citrus.
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China.
Citrus nucellar poly-embryony (NPE) is a mode of sporophytic apomixis that asexual embryos formed in the seed through adventitious embryogenesis from the somatic nucellar cells. NPE allows clonal propagation of rootstocks, but it impedes citrus cross breeding. To understand the cellular processes involved in NPE initiation, we profiled the transcriptomes and DNA methylomes in laser microdissection captured citrus apomictic cells. In apomictic cells, ribosome biogenesis and protein degradation were activated, whereas auxin polar transport was repressed. Reactive oxygen species (ROS) accumulated in the poly-embryonic ovules, and response to oxidative stress was provoked. The global DNA methylation level, especially that of CHH context, was decreased, whereas the methylation level of the NPE-controlling key gene CitRWP was increased. A C2H2 domain-containing transcription factor gene and CitRWP co-expressed specifically in apomictic cells may coordinate to initiate NPE. The activated embryogenic development and callose deposition processes indicated embryogenic fate of nucellar embryo initial (NEI) cells. In our working model for citrus NPE initiation, DNA hyper-methylation may activate transcription of CitRWP, which increases C2H2 expression and ROS accumulation, triggers epigenetic regulation and regulates cell fate transition and NEI cell identity in the apomictic cells.
PMID: 34424285
Foods , IF:4.35 , 2021 Sep , V10 (9) doi: 10.3390/foods10092196
Albedo- and Flavedo-Specific Transcriptome Profiling Related to Penicillium digitatum Infection in Citrus Fruit.
Department of Food Biotechnology, Instituto de Agroquimica y Tecnologia de Alimentos (IATA-CSIC), Av. Agustin Escardino 7, 46980 Paterna, Valencia, Spain.
Penicillium digitatum is the main postharvest pathogen of citrus fruit. Although the inner fruit peel part (albedo) is less resistant than the outer part (flavedo) to P. digitatum, the global mechanisms involved in their different susceptibility remain unknown. Here, we examine transcriptome differences between both tissues at fruit harvest and in their early responses to infection. At harvest, not only was secondary metabolism, involving phenylpropanoids, waxes, and terpenoids, generally induced in flavedo vs. albedo, but also energy metabolism, transcription factors (TFs), and biotic stress-related hormones and proteins too. Flavedo-specific induced responses to infection might be regulated in part by ERF1 TF, and are related to structural plant cell wall reinforcement. Other induced responses may be related to H2O2, the synthesis of phenylpropanoids, and the stress-related proteins required to maintain basal defense responses against virulent pathogens, whereas P. digitatum represses some hydrolase-encoding genes that play different functions and auxin-responsive genes in this peel tissue. In infected albedo, the repression of transport and signal transduction prevail, as does the induction of not only the processes related to the synthesis of flavonoids, indole glucosinolates, cutin, and oxylipins, but also the specific genes that elicit plant immunity against pathogens.
PMID: 34574307
Plant Physiol Biochem , IF:4.27 , 2021 Sep , V167 : P763-770 doi: 10.1016/j.plaphy.2021.09.013
Leaf size modulation by cytokinins in sesame plants.
Department of Biosciences, COMSATS University Islamabad (CUI), Park Road, Tarlai Kalan, 45550, Islamabad, Pakistan; Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, Avinguda Diagonal 643, E-08028, Barcelona, Spain.; Department of Biosciences, COMSATS University Islamabad (CUI), Park Road, Tarlai Kalan, 45550, Islamabad, Pakistan.; Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, Avinguda Diagonal 643, E-08028, Barcelona, Spain.; Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, Avinguda Diagonal 643, E-08028, Barcelona, Spain; Institute of Nutrition and Food Safety (INSA), University of Barcelona, Avinguda Diagonal 643, E-08028, Barcelona, Spain. Electronic address: smunne@ub.edu.
Phytohormones play important roles in controlling leaf size and in the modulation of various stress responses, including drought. In this study, hormone profiling analyses by ultra high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (UHPLC-MS/MS) was performed in leaves collected at three stages of active leaf growth to unravel which phytohormones modulate leaf size in sesame (Sesamum indicum L.) plants, an important oil-rich crop. Furthermore, endogenous contents of phytohormones were measured in parallel to various stress markers in sesame plants exposed to mild water deficit conditions by withholding water in potted plants for one week. Results revealed a major role of cytokinins and auxin in the modulation of leaf growth in sesame plants (which increased by 21.5 and 2.1-fold, respectively, with leaf growth), as well as a putative antagonistic response between jasmonic acid and salicylic acid during leaf development. Furthermore, growth arrest during water deficit stress appeared to be modulated by cytokinins, the endogenous contents of which decreased (by 48%) in parallel with ABA increases (by 59%). Reductions in the contents of the active cytokinin trans-zeatin occurred in parallel with increases in isopentenyladenine contents under drought, which suggests a partial metabolic limitation in cytokinin biosynthesis in leaves upon water deficit stress. These results provide useful information for the hormonal modulation of leaf size and the improvement of leaf growth and production in sesame plants through manipulation of the levels of key regulatory phytohormones.
PMID: 34530321
Environ Sci Pollut Res Int , IF:4.223 , 2021 Sep doi: 10.1007/s11356-021-16246-7
Amelioration of sodium and arsenic toxicity in Salvinia natans L. with 2,4-D priming through physiological responses.
Plant Physiology, Biochemistry and Plant Molecular Biology Research Unit, Department of Botany, University of Kalyani, Kalyani, 74 1235, Nadia, W.B., India.; Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, 1207, Bangladesh. mhzsauag@yahoo.com.; Plant Physiology, Biochemistry and Plant Molecular Biology Research Unit, Department of Botany, University of Kalyani, Kalyani, 74 1235, Nadia, W.B., India. mkadak09@gmail.com.
Sodium (Na) and arsenic (As) toxicity were monitored by hyperaccumulation of metals in Salvinia natans L. with 2,4-dichlorophenoxyacetic acid (2,4-D) induction. Salvinia was recorded with significant bioaccumulation of those metals with de-folding of cellular attributes in sustenance under toxic environment. 2,4-D priming has revised the growth components like net assimilation rate and relative water content to register initial plants' survival against Na and As. Proline biosynthesis supported in the maintenance of osmotic adjustment and plants sustained better activity through subdued electrolytic leakage. Oxidative stress due to both Na and As exposure is responsible for induction under significant moderation of lipid peroxidation and protein carbonization by 2,4-D application was evident to release the stress from metal and metalloids. Reactive oxygen species (ROS) like superoxide and hydrogen peroxide accumulation were monitored with activity of NADP(H)-oxidase. However, it was downregulated by 2,4-D to check the oxidative damages. Superoxide dismutase and peroxidases were significantly moderated to reduce the oxidative degradation for both metals with 2,4-D induction. Glutathione metabolism and recycling of ascorbate with monodehydroascorbate activity were other features to maintain the redox homeostasis for metal toxicity. At the molecular level, polymorphic variations of concern genes in redox cascades demarked significantly for those two metals and established the biomarker for those metals, respectively. As a whole, the biocompatibility of auxin herbicide in Salvinia may raise the possibility for auxin metabolism and thereby, the bioaccumulation to Na and As vis-a-vis tolerance for ecological safety is established.
PMID: 34495473
BMC Plant Biol , IF:4.215 , 2021 Sep , V21 (1) : P414 doi: 10.1186/s12870-021-03172-6
De novo transcriptome analysis provides insights into formation of in vitro adventitious root from leaf explants of Arnebia euchroma.
Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (IHBT), Palampur,, H.P.-176061, India.; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-, 201002, India.; Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (IHBT), Palampur,, H.P.-176061, India. vishal@ihbt.res.in.; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-, 201002, India. vishal@ihbt.res.in.; Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (IHBT), Palampur,, H.P.-176061, India. sbhushan@ihbt.res.in.; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-, 201002, India. sbhushan@ihbt.res.in.; Dietetics & Nutrition Technology Division, CSIR-Institute of Himalayan Bioresource Technology (IHBT), Palampur,, H.P.-176061, India. sbhushan@ihbt.res.in.
BACKGROUND: Adventitious root formation is considered a major developmental step during the propagation of difficult to root plants, especially in horticultural crops. Recently, adventitious roots induced through plant tissue culture methods have also been used for production of phytochemicals such as flavonoids, anthocyanins and anthraquinones. It is rather well understood which horticultural species will easily form adventitious roots, but the factors affecting this process at molecular level or regulating the induction process in in vitro conditions are far less known. The present study was conducted to identify transcripts involved in in vitro induction and formation of adventitious roots using Arnebia euchroma leaves at different time points (intact leaf (control), 3 h, 12 h, 24 h, 3 d, 7 d, 10 d and 15 d). A. euchroma is an endangered medicinal Himalayan herb whose root contains red naphthoquinone pigments. These phytoconstituents are widely used as an herbal ingredient in Asian traditional medicine as well as natural colouring agent in food and cosmetics. RESULTS: A total of 137.93 to 293.76 million raw reads were generated and assembled to 54,587 transcripts with average length of 1512.27 bps and N50 of 2193 bps, respectively. In addition, 50,107 differentially expressed genes were identified and found to be involved in plant hormone signal transduction, cell wall modification and wound induced mitogen activated protein kinase signalling. The data exhibited dominance of auxin responsive (AUXIN RESPONSE FACTOR8, IAA13, GRETCHEN HAGEN3.1) and sucrose translocation (BETA-31 FRUCTOFURANOSIDASE and MONOSACCHARIDE-SENSING protein1) genes during induction phase. In the initiation phase, the expression of LATERAL ORGAN BOUNDARIES DOMAIN16, EXPANSIN-B15, ENDOGLUCANASE25 and LEUCINE-rich repeat EXTENSION-like proteins was increased. During the expression phase, the same transcripts, with exception of LATERAL ORGAN BOUNDARIES DOMAIN16 were identified. Overall, the transcriptomic analysis revealed a similar patterns of genes, however, their expression level varied in subsequent phases of in vitro adventitious root formation in A. euchroma. CONCLUSION: The results presented here will be helpful in understanding key regulators of in vitro adventitious root development in Arnebia species, which may be deployed in the future for phytochemical production at a commercial scale.
PMID: 34503445
BMC Plant Biol , IF:4.215 , 2021 Sep , V21 (1) : P410 doi: 10.1186/s12870-021-03195-z
LncRNA TCONS_00021861 is functionally associated with drought tolerance in rice (Oryza sativa L.) via competing endogenous RNA regulation.
School of Chemistry and Life Science, Suzhou University of Science and Technology, No.1 Kerui Road, 215011, Suzhou, China. njucjj@126.com.; School of Chemistry and Life Science, Suzhou University of Science and Technology, No.1 Kerui Road, 215011, Suzhou, China.
BACKGROUND: Water deficit is an abiotic stress that retards plant growth and destabilizes crop production. Long non coding RNAs (lncRNAs) are a class of non-coding endogenous RNAs that participate in diverse cellular processes and stress responses in plants. lncRNAs could function as competing endogenous RNAs (ceRNA) and represent a novel layer of gene regulation. However, the regulatory mechanism of lncRNAs as ceRNA in drought stress response is yet unclear. RESULTS: In this study, we performed transcriptome-wide identification of drought-responsive lncRNAs in rice. Thereafter, we constructed a lncRNA-mediated ceRNA network by analyzing competing relationships between mRNAs and lncRNAs based on ceRNA hypothesis. A drought responsive ceRNA network with 40 lncRNAs, 23 miRNAs and 103 mRNAs was obtained. Network analysis revealed TCONS_00021861/miR528-3p/YUCCA7 regulatory axis as a hub involved in drought response. The miRNA-target expression and interaction were validated by RT-qPCR and RLM-5'RACE. TCONS_00021861 showed significant positive correlation (r = 0.7102) with YUCCA7 and negative correlation with miR528-3p (r = -0.7483). Overexpression of TCONS_00021861 attenuated the repression of miR528-3p on YUCCA7, leading to increased IAA (Indole-3-acetic acid) content and auxin overproduction phenotypes. CONCLUSIONS: TCONS_00021861 could regulate YUCCA7 by sponging miR528-3p, which in turn activates IAA biosynthetic pathway and confer resistance to drought stress. Our findings provide a new perspective of the regulatory roles of lncRNAs as ceRNAs in drought resistance of rice.
PMID: 34493227
Tree Physiol , IF:4.196 , 2021 Sep doi: 10.1093/treephys/tpab110
Auxin concentration and xylem production of P. massoniana in a subtropical forest in south China.
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou 510650, China.; Center for Plant Ecology, Core Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou 510650, China.; University of Chinese Academy of Sciences, 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China.; Departement des Sciences Fondamentales, Universite du Quebec a Chicoutimi, Chicoutimi (QC) G7H2B1, Canada.; Key Laboratory of Geospatial Technology for Middle and Lower Yellow River Regions, Henan University, Henan 475004, China.
Auxin is involved in various developmental processes of plants, including cell division in cambium and xylem differentiation. However, most studies linking auxin and xylem cell production are performed in environments with a strong seasonality (i.e., temperate and boreal climates). The temporal dynamics of auxin and cambial activity of subtropical trees remain basically unknown. In this study, we sampled four microcores weekly in three individuals of Chinese red pine (P. massoniana Lamb.) from February to December 2015-2016 to compare xylem formation with auxin concentration in subtropical China. During the entire period of sampling, the number of cambial cells varied from 2 to 7, while the number of cells in enlarging zone ranged from 1 to 4 and from 1 to 5 in wall-thickening zone. In 2015, average auxin concentration was 3.46 ng/g, with 33 xylem cells being produced at the end of the year. In 2016, a lower auxin concentration (2.59 ng/g) corresponded to a reduced annual xylem production (13.7 cells). No significant relationship between auxin concentration and number of xylem cells in differentiation was found at weekly scale. Unlike in boreal and temperate forests, the lack of wood formation seasonality in subtropical forests makes it more difficult to reveal the relationship between auxin concentration and number of xylem cells in differentiation at intra-annual scale. The frequent and repeated samplings might have reduced auxin concentration in the developing cambium and xylem, resulting in a lower xylem cell production.
PMID: 34505152
Tree Physiol , IF:4.196 , 2021 Sep , V41 (9) : P1669-1684 doi: 10.1093/treephys/tpab030
Interpretation of the difference in shade tolerance of two subtropical forest tree species of different successional stages at the transcriptome and physiological levels.
Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China.; Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Institute of Plant Protection, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, PR China.
Differences in plant shade tolerance constitute a major mechanism driving the succession of forest communities in subtropical forests. However, the indirect effects of differences in light requirements on the growth of mid- and late-successional tree species are unclear, and this potential growth effect has not been explained at the transcriptome level. Here, a typical mid-successional dominant tree species, Schima superba Gardn. et Champ, and a typical late-successional dominant tree species, Cryptocarya concinna Hance were used as materials and planted under 100% full light (FL) and 30% FL (low light, LL) to explore the responses of tree species in different successional stages of subtropical forests to different light environments. Transcriptome sequencing was used to analyze the expression changes in genes related to growth and photoprotection under different light environments. The young leaves of S. superba accumulated more malondialdehyde (MDA) and superoxide radicals ($\{\mathrm\{O\}\}_2^\{\{\{\}^\{\bullet\}\}^\{-\}\}$) under LL. A lower hormone content (auxin, cytokinin, gibberellin) in the young leaves, a weaker photosynthetic capacity in the mature leaves and significant downregulation of related gene expression were also found under LL, which resulted in the total biomass of S. superba under LL being lower than that under FL. The young leaves of C. concinna had less MDA and $\{\mathrm\{O\}\}_2^\{\{\{\}^\{\bullet\}\}^\{-\}\}$, and a higher hormone contents under LL than those under FL. There was no significant difference in photosynthetic capacity between mature leaves in contrasting light environments. Although the biomass of C. concinna under LL was less than that under FL, the height of C. concinna under LL was higher than that under FL, indicating that C. concinna could grow well under the two light environments. Our results describing the acclimatization of light at the physiological, molecular and transcriptome levels are important for a complete understanding of successional mechanisms.
PMID: 33611548
Mol Plant Microbe Interact , IF:4.171 , 2021 Sep : PMPMI02210036R doi: 10.1094/MPMI-02-21-0036-R
Three Common Symbiotic ABC Subfamily B Transporters in Medicago truncatula Are Regulated by a NIN-Independent Branch of the Symbiosis Signaling Pathway.
John Innes Centre, Norwich, NR4 7UH, U.K.; Noble Research Institute, Ardmore, OK 73401, U.S.A.; CAS-JIC Centre of Excellence for Plant and Microbial Science (CEPAMS), Centre for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, 300 Feng Lin Road, Shanghai 200032, China.; Shanghai Engineering Research Center of Plant Germplasm Resource, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China.
Several ATP-binding cassette (ABC) transporters involved in the arbuscular mycorrhizal symbiosis and nodulation have been identified. We describe three previously unreported ABC subfamily B transporters, named AMN1, AMN2, and AMN3 (ABCB for mycorrhization and nodulation), that are expressed early during infection by rhizobia and arbuscular mycorrhizal fungi. These ABCB transporters are strongly expressed in symbiotically infected tissues, including in root-hair cells with rhizobial infection threads and arbusculated cells. During nodulation, the expression of these genes is highly induced by rhizobia and purified Nod factors and is dependent on DMI3 but is not dependent on other known major regulators of infection, such as NIN, NSP1, or NSP2. During mycorrhization their expression is dependent on DMI3 and RAM1 but not on NSP1 and NSP2. Therefore, they may be commonly regulated through a distinct branch of the common symbiotic pathway. Mutants with exonic Tnt1-transposon insertions were isolated for all three genes. None of the single or double mutants showed any differences in colonization by either rhizobia or mycorrhizal fungi, but the triple amn1 amn2 amn3 mutant showed an increase in nodule number. Further studies are needed to identify potential substrates of these transporters and understand their roles in these beneficial symbioses.[Formula: see text] Copyright (c) 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
PMID: 33779265
Microorganisms , IF:4.128 , 2021 Sep , V9 (9) doi: 10.3390/microorganisms9091924
From Strain Characterization to Field Authorization: Highlights on Bacillus velezensis Strain B25 Beneficial Properties for Plants and Its Activities on Phytopathogenic Fungi.
Greentech, Biopole Clermont-Limagne, 63360 Saint Beauzire, France.; LABGeM, Genomique Metabolique, Genoscope, Institut Francois Jacob, CEA, CNRS, Universite d'Evry, Universite Paris-Saclay, 2 Rue Gaston Cremieux, 91057 Evry, France.; Plants and Pathogens Group, Research Institute Land Nature and Environment, Geneva School of Engineering, Architecture and Landscape (HEPIA), HES-SO University of Applied Sciences and Arts Western Switzerland, 1254 Jussy, Switzerland.
Agriculture is in need of alternative products to conventional phytopharmaceutical treatments from chemical industry. One solution is the use of natural microorganisms with beneficial properties to ensure crop yields and plant health. In the present study, we focused our analyses on a bacterium referred as strain B25 and belonging to the species Bacillus velezensis (synonym B. amyloliquefaciens subsp. plantarum or B. methylotrophicus), a promising plant growth promoting rhizobacterium (PGPR) and an inhibitor of pathogenic fungi inducing crops diseases. B25 strain activities were investigated. Its genes are well preserved, with their majority being common with other Bacillus spp. strains and responsible for the biosynthesis of secondary metabolites known to be involved in biocontrol and plant growth-promoting activities. No antibiotic resistance genes were found in the B25 strain plasmid. In vitro and in planta tests were conducted to confirm these PGPR and biocontrol properties, showing its efficiency against 13 different pathogenic fungi through antibiosis mechanism. B25 strain also showed good capacities to quickly colonize its environment, to solubilize phosphorus and to produce siderophores and little amounts of auxin-type phytohormones (around 13,051 microg/mL after 32 h). All these findings combined to the fact that B25 demonstrated good properties for industrialization of the production and an environmental-friendly profile, led to its commercialization under market authorization since 2018 in several biostimulant preparations and opened its potential use as a biocontrol agent.
PMID: 34576819
Planta , IF:4.116 , 2021 Sep , V254 (4) : P69 doi: 10.1007/s00425-021-03719-9
Functional analysis of indole 3-hexanoic acid as a novel auxin from Arabidopsis thaliana.
College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.; Institute of Industrial Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, People's Republic of China.; Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Nanjing, 210014, People's Republic of China.; College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China. fenglin123@njau.edu.cn.; College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China. zhangqun@njau.edu.cn.
MAIN CONCLUSION: Indole 3-hexanoic acid is a novel auxin and regulates plant growth and development. Auxin is a signaling molecule that influences most aspects of plant development. Although many small bioactive molecules have been developed as auxin analogues, naturally occurring auxin and the detailed mechanisms of its specific actions in plants remain to be fully elucidated. In this study, to screen auxin responses, we used a novel picolinate synthetic auxin, 3-indole hexanoic acid (IHA), which is similar in structure to indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA). IHA showed classical auxin activity in the regulation of root growth, gene expression, and PIN-FORMED abundance. Physiological and genetic analyses indicated that IHA may be perceived by the auxin receptor TIR1 and transported by the G-class ATP-binding cassette protein ABCG36 and its homolog ABCG37. Importantly, IHA was detected in planta and converted into IBA depending on the peroxisomal beta-oxidation. Together, these findings reveal a novel auxin pathway component and suggest possible undiscovered modes of auxin metabolism regulation in plants.
PMID: 34498125
Planta , IF:4.116 , 2021 Sep , V254 (4) : P65 doi: 10.1007/s00425-021-03709-x
Involvement of the auxin-cytokinin homeostasis in adventitious root formation of rose cuttings as affected by their nodal position in the stock plant.
University of Kabianga, P.O. Box 2030-20200, Kericho, Kenya.; Leibniz Institute of Vegetable and Ornamental Crops (IGZ), 99090, Erfurt, Germany.; Maseno University, P.O. Box Private Bag, Maseno, Kenya.; Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62, Nairobi, 000-00200, Kenya.; Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, 06466, Stadt Seeland, Germany.; Leibniz Institute of Vegetable and Ornamental Crops (IGZ), 99090, Erfurt, Germany. uwe.druege@fh-erfurt.de.; Erfurt Research Centre for Horticultural Crops (FGK), University of Applied Sciences Erfurt, 99090, Erfurt, Germany. uwe.druege@fh-erfurt.de.
MAIN CONCLUSION: Enhanced levels of indole-3-acetic and raised auxin to cytokinin ratios in the stem base contribute to the positive acropetal gradient in rooting capacity of leafy single-node stem cuttings of rose. Cuttings excised from different nodal positions in stock plants can differ in subsequent adventitious root formation. We investigated the involvement of the auxin-cytokinin balance in position-affected rooting of Rosa hybrida. Leafy single-node stem cuttings of two rose cultivars were excised from top versus bottom positions. Concentrations of IAA and cytokinins were monitored in the bud region and the stem base during 8 days after planting using chromatography-MS/MS technology. The effects of nodal position and external supply of indole-butyric acid on rooting were analyzed. Most cytokinins increased particularly in the bud region and peaked at day two before the bud break was recorded. IAA increased in both tissues between day one and day eight. Top versus bottom cuttings revealed higher levels of isopentenyladenosine (IPR) in both tissues as well as higher concentrations of IAA and a higher ratio of IAA to cytokinins particularly in the stem base. The dynamic of hormones and correlation analysis indicated that the higher IPR contributed to the enhanced IAA in the bud region which served as auxin source for the auxin homeostasis in the stem base, where IAA determined the auxin-cytokinin balance. Bottom versus top cuttings produced lower numbers and lengths of roots, whereas this deficit was counterbalanced by auxin application. Further considering other studies of rose, it is concluded that cytokinin-, sucrose- and zinc-dependent auxin biosynthesis in the outgrowing buds is an important factor that contributes to the enhanced IAA levels and auxin/cytokinin ratios in the stem base of apical cuttings, promoting root induction.
PMID: 34487248
Am J Bot , IF:3.844 , 2021 Sep doi: 10.1002/ajb2.1733
Plasmodesmata and hormones: pathways for plant development.
Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA.
PMID: 34580857
Am J Bot , IF:3.844 , 2021 Sep doi: 10.1002/ajb2.1728
Light signals counteract alterations caused by simulated microgravity in proliferating plant cells.
Centro de Investigaciones Biologicas Margarita Salas - CSIC, Ramiro de Maeztu 9, Madrid, 28040, Spain.; GSBMS/AMIS, Universite Paul Sabatier Toulouse III, Toulouse, France.; CNRS, Laboratoire Genome et Developpement des Plantes (LGDP), UMR 5096, Perpignan, 66860, France.; Universite de Perpignan Via Domitia, LGDP, UMR 5096, Perpignan, 66860, France.
PREMISE: Light and gravity are fundamental cues for plant development. Our understanding of the effects of light stimuli on plants in space, without gravity, is key to providing conditions for plants to acclimate to the environment. Here we tested the hypothesis that the alterations caused by the absence of gravity in root meristematic cells can be counteracted by light. METHODS: Seedlings of wild-type Arabidopsis thaliana and two mutants of the essential nucleolar protein nucleolin (nuc1, nuc2) were grown in simulated microgravity, either under a white light photoperiod or under continuous darkness. Key variables of cell proliferation (cell cycle regulation), cell growth (ribosome biogenesis), and auxin transport were measured in the root meristem using in situ cellular markers and transcriptomic methods and compared with those of a 1 g control. RESULTS: The incorporation of a photoperiod regime was sufficient to attenuate or suppress the effects caused by gravitational stress at the cellular level in the root meristem. In all cases, values for variables recorded from samples receiving light stimuli in simulated microgravity were closer to values from the controls than values from samples grown in darkness. Differential sensitivities were obtained for the two nucleolin mutants. CONCLUSIONS: Light signals may totally or partially replace gravity signals, significantly improving plant growth and development in microgravity. Despite that, molecular alterations are still compatible with the expected acclimation mechanisms, which need to be better understood. The differential sensitivity of nuc1 and nuc2 mutants to gravitational stress points to new strategies to produce more resilient plants to travel with humans in new extraterrestrial endeavors.
PMID: 34524692
Protoplasma , IF:3.356 , 2021 Sep doi: 10.1007/s00709-021-01705-2
Plant growth-promoting and non-promoting rhizobacteria from avocado trees differentially emit volatiles that influence growth of Arabidopsis thaliana.
Red de Biodiversidad y Sistematica, Instituto de Ecologia A.C., Carretera Antigua a Coatepec 351, El Haya, 91073, Xalapa, Veracruz, Mexico.; Department of Biotechnology and Biochemistry, CINVESTAV Unidad Irapuato, Km. 9.6 Libramiento Norte Carretera Irapuato-Leon, 36821, Irapuato, Guanajuato, Mexico.; Red de Estudios Moleculares Avanzados, Cluster BioMimic(R), Instituto de Ecologia A.C., Carretera Antigua a Coatepec 351, El Haya, 91073, Xalapa, Veracruz, Mexico.; Red de Biodiversidad y Sistematica, Instituto de Ecologia A.C., Carretera Antigua a Coatepec 351, El Haya, 91073, Xalapa, Veracruz, Mexico. gloria.carrion@inecol.mx.; Red de Estudios Moleculares Avanzados, Cluster BioMimic(R), Instituto de Ecologia A.C., Carretera Antigua a Coatepec 351, El Haya, 91073, Xalapa, Veracruz, Mexico. randy.ortiz@inecol.mx.
Microbial volatile organic compounds (mVOCs) play important roles in inter- and intra-kingdom interactions, and they are also important as signal molecules in physiological processes acting either as plant growth-promoting or negatively modulating plant development. We investigated the effects of mVOCs emitted by PGPR vs non-PGPR from avocado trees (Persea americana) on growth of Arabidopsis thaliana seedlings. Chemical diversity of mVOCs was determined by SPME-GC-MS; selected compounds were screened in dose-response experiments in A. thaliana transgenic lines. We found that plant growth parameters were affected depending on inoculum concentration. Twenty-six compounds were identified in PGPR and non-PGPR with eight of them not previously reported. The VOCs signatures were differential between those groups. 4-methyl-2-pentanone, 1-nonanol, 2-phenyl-2-propanol and ethyl isovalerate modified primary root architecture influencing the expression of auxin- and JA-responsive genes, and cell division. Lateral root formation was regulated by 4-methyl-2-pentanone, 3-methyl-1-butanol, 1-nonanol and ethyl isovalerate suggesting a participation via JA signalling. Our study revealed the differential emission of volatiles by PGPR vs non-PGPR from avocado trees and provides a general view about the mechanisms by which those volatiles influence plant growth and development. Rhizobacteria strains and mVOCs here reported are promising for improvement the growth and productivity of avocado crop.
PMID: 34529144
Protoplasma , IF:3.356 , 2021 Sep doi: 10.1007/s00709-021-01697-z
Plant root development: is the classical theory for auxin-regulated root growth false?
Institut fur Biologiedidaktik, Universitat zu Koln, Cologne, Germany. h.edelmann@uni-koeln.de.
One of the longest standing theories and, therein-based, regulation-model of plant root development, posits the inhibitory action of auxin (IAA, indolylacetic acid) on elongation growth of root cells. This effect, as induced by exogenously supplied IAA, served as the foundation stone for root growth regulation. For decades, auxin ruled the day and only allowed hormonal side players to be somehow involved, or in some way affected. However, this copiously reiterated, apparent cardinal role of auxin only applies in roots immersed in solutions; it vanishes as soon as IAA-supplied roots are not surrounded by liquid. When roots grow in humid air, exogenous IAA has no inhibitory effect on elongation growth of maize roots, regardless of whether it is applied basipetally from the top of the root or to the entire residual seedling immersed in IAA solution. Nevertheless, such treatment leads to pronounced root-borne ethylene emission and lateral rooting, illustrating and confirming thereby induced auxin presence and its effect on the root - yet, not on root cell elongation. Based on these findings, a new root growth regulatory model is proposed. In this model, it is not IAA, but IAA-triggered ethylene which plays the cardinal regulatory role - taking effect, or not - depending on the external circumstances. In this model, in water- or solution-incubated roots, IAA-dependent ethylene acts due to its accumulation within the root proper by inhibited/restrained diffusion into the liquid phase. In roots exposed to moist air or gas, there is no effect on cell elongation, since IAA-triggered ethylene diffuses out of the root without an impact on growth.
PMID: 34515860
PLoS One , IF:3.24 , 2021 , V16 (9) : Pe0248796 doi: 10.1371/journal.pone.0248796
Evidence that synergism between potassium and nitrate enhances the alleviation of ammonium toxicity in rice seedling roots.
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China.
Ammonium toxicity in plants is considered a global phenomenon, but the primary mechanisms remain poorly characterized. Here, we show that although the addition of potassium or nitrate partially alleviated the inhibition of rice seedling root growth caused by ammonium toxicity, the combination of potassium and nitrate clearly improved the alleviation, probably via some synergistic mechanisms. The combined treatment with potassium and nitrate led to significantly improved alleviation effects on root biomass, root length, and embryonic crown root number. The aberrant cell morphology and the rhizosphere acidification level caused by ammonium toxicity, recovered only by the combined treatment. RNA sequencing analysis and weighted gene correlation network analysis (WGCNA) revealed that the transcriptional response generated from the combined treatment involved cellulose synthesis, auxin, and gibberellin metabolism. Our results point out that potassium and nitrate combined treatment effectively promotes cell wall formation in rice, and thus, effectively alleviates ammonium toxicity.
PMID: 34499661
PLoS One , IF:3.24 , 2021 , V16 (9) : Pe0250678 doi: 10.1371/journal.pone.0250678
Interaction of the causal agent of apricot bud gall Acalitus phloeocoptes (Nalepa) with apricot: Implications in infested tissues.
College of Plant Protection, Gansu Agricultural University, Lanzhou, China.; School of Biochemistry and Biotechnology, University of the Punjab, Lahore, Pakistan.; Gansu Agriculture Vocational and Technical College, Horticulture Technology, Lanzhou, Gansu, China.; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, China.; College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu, China.; Department of Horticulture, FoA, University for Development Studies, Tamale, Ghana.; College of Agriculture, Bahauddin Zakariya University, Multan, Bahadur Sub Campus Layyah, Pakistan.; Institute of Agricultural Sciences, University of the Punjab, Lahore, Pakistan.
Apricot bud gall mite, Acalitus phloeocoptes (Nalepa), is a destructive arthropod pest that causes significant economic losses to apricot trees worldwide. The current study explores the ways to understand the mode of dispersal of A. phloeocoptes, the development and ultrastructure of apricot bud gall, and the role of phytohormones in the formation of the apricot bud galls. The results demonstrated that the starch granules in the bud axon were extended at the onset of the attack. During the later stages of the attack, the cytoplasm was found to deteriorate in infected tissues. Furthermore, we have observed that the accumulation of large amounts of cytokinin (zeatin, ZT) and auxin (indoleacetic acid, IAA) led to rapid bud proliferation during rapid growth period, while abscisic acid (ABA) controls the development of gall buds and plays a vital role in gall bud maturity. The reduction of gibberellic acid (GA3) content led to rapid lignification at the later phase of bud development. Overall, our results have revealed that the mechanism underlying the interaction of apricot bud gall with its parasite and have provided reliable information for designing valuable Apricot breeding programs. This study will be quite useful for pest management and will provide a comprehensive evaluation of ecology-based cost-effective control, life history and demographic parameters of A. phloeocoptes.
PMID: 34473720
Funct Plant Biol , IF:3.101 , 2021 Sep doi: 10.1071/FP20360
Abscisic acid stimulates wound suberisation in kiwifruit (Actinidia chinensis) by regulating the production of jasmonic acid, cytokinin and auxin.
Wounding induces a cascade of correlative physiological responses that lead to the repair of damaged tissue. In this study, the effect of wounding on suberin, endogenous hormones and their metabolic genes expression was observed during the wound healing of kiwifruit (Actinidia chinensis Planch.). In addition, the role of abscisic acid (ABA) in wound suberisation was investigated by analysing the coordinated regulation between ABA and other hormones. The wound healing process in kiwifruit could be divided into two stages including: (1) initial accumulation of suberin polyphenolic (SPP) and long carbon chain suberin polyaliphatic monomers (LSPA) before 24h; and (2) massive synthesis of SPP and very long carbon chain suberin polyaliphatic monomers (VLSPA) after 24h. ABA content rapidly increased and induced the jasmonic acid (JA) biosynthesis at the early stage of wound healing. ABA level gradually decreased with the expression of AchCYP707A genes, while the contents of trans-zeatin (t-ZT) and indole-3-acetic acid (IAA) steadily increased at the late stage of wound healing. Exogenous ABA stimulated JA and suberin monomers accumulation, but suppressed both t-ZT and IAA biosynthesis. The role of ABA in wound healing of kiwifruit might be involved in the coordination of both JA-mediated suberin monomers biosynthesis and t-ZT- and IAA-mediated formation of suberised cells via an interaction mechanism.
PMID: 34551855
Appl Biochem Biotechnol , IF:2.926 , 2021 Sep doi: 10.1007/s12010-021-03660-3
Genome Mining of Three Plant Growth-Promoting Bacillus Species from Maize Rhizosphere.
Food Security and Safety Niche Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, 2735, South Africa.; Food Security and Safety Niche Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, 2735, South Africa. olubukola.babalola@nwu.ac.za.
Bacillus species genomes are rich in plant growth-promoting genetic elements. Bacillus subtilis and Bacillus velezensis are important plant growth promoters; hence, to further improve their abilities, the genetic elements responsible for these traits were characterized and reported. Genetic elements reported include those of auxin, nitrogen fixation, siderophore production, iron acquisition, volatile organic compounds, and antibiotics. Furthermore, the presence of phages and antibiotic-resistant genes in the genomes are reported. Pan-genome analysis was conducted using ten Bacillus species. From the analysis, pan-genome of Bacillus subtilis and Bacillus velezensis are still open. Ultimately, this study brings an insight into the genetic components of the plant growth-promoting abilities of these strains and shows their potential biotechnological applications in agriculture and other relevant sectors.
PMID: 34529229
Plant Signal Behav , IF:2.247 , 2021 Sep , V16 (9) : P1925440 doi: 10.1080/15592324.2021.1925440
Functions of long non-coding RNA in Arabidopsis thaliana.
CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.
A major part of the eukaryotic genome is transcribed into non-coding RNAs (ncRNAs) having no protein coding potential. ncRNAs which are longer than 200 nucleotides are categorized as long non coding RNAs (lncRNAs). Most lncRNAs are induced as a consequence of various environmental and developmental cues. Among plants, the functions of lncRNAs are best studied in Arabidopsis thaliana. In this review, we highlight the important functional roles of various lncRNAs during different stages of Arabidopsis life cycle and their response to environmental changes. These lncRNAs primarily govern processes such as flowering, seed germination, stress response, light- and auxin-regulated development, and RNA-dependent DNA methylation (RdDM). Major challenge is to differentiate between functional and cryptic transcripts. Genome editing, large scale RNAi and computational approaches may help to identify and characterize novel functional lncRNAs in Arabidopsis.
PMID: 33980126
Plant Signal Behav , IF:2.247 , 2021 Sep , V16 (9) : P1926131 doi: 10.1080/15592324.2021.1926131
A dual mode of ethylene actions contributes to the optimization of hypocotyl growth under fluctuating temperature environments.
Department of Chemistry, Seoul National University, Seoul, Korea.; Plant Genomics and Breeding Institute, Seoul National University, Seoul, Korea.
The gaseous phytohormone ethylene plays versatile roles in sustaining plant growth and fitness in response to environmental changes, such as light illumination, flooding, and mechanical pressure. Interestingly, it is well known that the effects of ethylene on plant growth vary profoundly, depending on external conditions. For example, light/dark conditions alter the directionality of ethylene action on hypocotyl growth. Similarly, a recent study has shown that the effects of ethylene on hypocotyl growth are reversed during temperature increases: ethylene attenuates hypocotyl elongation in the light at warm temperatures (28 degrees C), while promoting it at normal temperatures (22 degrees C). The ethylene-activated ETHYLENE-INSENSITIVE 3 (EIN3) transcription factor directly promotes the transcription of both PHYTOCHROM INTERACTING FACTOR 3 (PIF3) and ARABIDOPSIS PP2C CLADE D7 (APD7) genes. At 22 degrees C, the auxin activity is tuned down, and thus ethylene promotes hypocotyl growth via the PIF3-mediated microtubule reorganization. On the other hand, when auxin highly accumulates at 28 degrees C, the ethylene-directed growth repression is potentiated through the APD7-mediated repression of auxin responses. APD7 plays a role in integrating ethylene cues into auxin signaling. We propose that the dual mode of EIN3-mediated ethylene actions enables plants to optimize growth under constantly changing environments.
PMID: 33975509
Adv Biol (Weinh) , 2021 Sep : Pe2100953 doi: 10.1002/adbi.202100953
Probing DNA - Transcription Factor Interactions Using Single-Molecule Fluorescence Detection in Nanofluidic Devices.
Laboratory of Biophysics, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.; Laboratory of Biochemistry, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.; Groningen Research Institute of Pharmacy, Pharmaceutical Analysis, University of Groningen, P.O. Box 196, 9700 AD, Groningen, The Netherlands.; Stichting Imec Nederland within OnePlanet Research Center, Bronland 10, Wageningen, 6708 WH, The Netherlands.; Microspectroscopy Research Facility, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.
Single-molecule fluorescence detection offers powerful ways to study biomolecules and their complex interactions. Here, nanofluidic devices and camera-based, single-molecule Forster resonance energy transfer (smFRET) detection are combined to study the interactions between plant transcription factors of the auxin response factor (ARF) family and DNA oligonucleotides that contain target DNA response elements. In particular, it is shown that the binding of the unlabeled ARF DNA binding domain (ARF-DBD) to donor and acceptor labeled DNA oligonucleotides can be detected by changes in the FRET efficiency and changes in the diffusion coefficient of the DNA. In addition, this data on fluorescently labeled ARF-DBDs suggest that, at nanomolar concentrations, ARF-DBDs are exclusively present as monomers. In general, the fluidic framework of freely diffusing molecules minimizes potential surface-induced artifacts, enables high-throughput measurements, and proved to be instrumental in shedding more light on the interactions between ARF-DBDs monomers and between ARF-DBDs and their DNA response element.
PMID: 34472724