Nature , IF:49.962 , 2024 Aug , V632 (8025) : P576-584 doi: 10.1038/s41586-024-07669-6
Maize smart-canopy architecture enhances yield at high densities.
State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, National Maize Improvement Center, Center for Crop Functional Genomics and Molecular Breeding, Key Laboratory of Biology and Genetic Improvement of Maize (MOA), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China.; Maize Research Institute, Beijing Academy of Agriculture and Forestry Sciences (BAAFS), Beijing, China.; Sanya Institute of China Agricultural University, Sanya, China.; State Key Laboratory of Plant Environmental Resilience, Center for Crop Functional Genomics and Molecular Breeding, College of Biological Sciences, China Agricultural University, Beijing, China.; National Maize Improvement Center of China, Key Laboratory of Crop Heterosis and Utilization (MOE), China Agricultural University, Beijing, China.; Hainan Aoyu Biotechnology, Sanya, China.; Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, USA.; State Key Laboratory of Plant Environmental Resilience, Engineering Research Center of Plant Growth Regulator, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, China.; Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agricultural Sciences at Weifang, Weifang, China.; State Key Laboratory of Plant Environmental Resilience, Center for Crop Functional Genomics and Molecular Breeding, College of Biological Sciences, China Agricultural University, Beijing, China. jigangli@cau.edu.cn.; State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, National Maize Improvement Center, Center for Crop Functional Genomics and Molecular Breeding, Key Laboratory of Biology and Genetic Improvement of Maize (MOA), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China. ft55@cau.edu.cn.; Sanya Institute of China Agricultural University, Sanya, China. ft55@cau.edu.cn.
Increasing planting density is a key strategy for enhancing maize yields(1-3). An ideotype for dense planting requires a 'smart canopy' with leaf angles at different canopy layers differentially optimized to maximize light interception and photosynthesis(4-6), among other features. Here we identified leaf angle architecture of smart canopy 1 (lac1), a natural mutant with upright upper leaves, less erect middle leaves and relatively flat lower leaves. lac1 has improved photosynthetic capacity and attenuated responses to shade under dense planting. lac1 encodes a brassinosteroid C-22 hydroxylase that predominantly regulates upper leaf angle. Phytochrome A photoreceptors accumulate in shade and interact with the transcription factor RAVL1 to promote its degradation via the 26S proteasome, thereby inhibiting activation of lac1 by RAVL1 and decreasing brassinosteroid levels. This ultimately decreases upper leaf angle in dense fields. Large-scale field trials demonstrate that lac1 boosts maize yields under high planting densities. To quickly introduce lac1 into breeding germplasm, we transformed a haploid inducer and recovered homozygous lac1 edits from 20 diverse inbred lines. The tested doubled haploids uniformly acquired smart-canopy-like plant architecture. We provide an important target and an accelerated strategy for developing high-density-tolerant cultivars, with lac1 serving as a genetic chassis for further engineering of a smart canopy in maize.
PMID: 38866052
Plant Cell , IF:11.277 , 2024 Jul , V36 (8) : P2893-2907 doi: 10.1093/plcell/koae147
A transthyretin-like protein acts downstream of miR397 and LACCASE to regulate grain yield in rice.
Guangdong Provincial Key Laboratory of Plant Resources, State Key Laboratory for Biocontrol, School of Life Science, Sun Yat-Sen University, Guangzhou 510275, P. R. China.; Guangdong Key Laboratory of Crop Germplasm Resources Preservation and Utilization, Key Laboratory of South China Modern Biological Seed Industry, Ministry of Agriculture and Rural Affairs, Agro-biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, P. R. China.; Guangdong Key Laboratory of New Technology in Rice Breeding, Guangdong Rice Engineering Laboratory, Rice Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, P. R. China.
Increasing grain yield is a major goal of breeders due to the rising global demand for food. We previously reported that the miR397-LACCASE (OsLAC) module regulates brassinosteroid (BR) signaling and grain yield in rice (Oryza sativa). However, the precise roles of laccase enzymes in the BR pathway remain unclear. Here, we report that OsLAC controls grain yield by preventing the turnover of TRANSTHYRETIN-LIKE (OsTTL), a negative regulator of BR signaling. Overexpressing OsTTL decreased BR sensitivity in rice, while loss-of-function of OsTTL led to enhanced BR signaling and increased grain yield. OsLAC directly binds to OsTTL and regulates its phosphorylation-mediated turnover. The phosphorylation site Ser226 of OsTTL is essential for its ubiquitination and degradation. Overexpressing the dephosphorylation-mimic form of OsTTL (OsTTLS226A) resulted in more severe defects than did overexpressing OsTTL. These findings provide insight into the role of an ancient laccase in BR signaling and suggest that the OsLAC-OsTTL module could serve as a target for improving grain yield.
PMID: 38735686
Proc Natl Acad Sci U S A , IF:11.205 , 2024 Sep , V121 (36) : Pe2403040121 doi: 10.1073/pnas.2403040121
SlCPK27 cross-links SlHY5 and SlPIF4 in brassinosteroid-dependent photo- and thermo-morphogenesis in tomato.
Department of Horticulture, Zhejiang University, Hangzhou 310058, China.; Hainan Institute, Zhejiang University, Yazhou Bay Science and Technology City, Sanya 572025, China.; Key Laboratory of Horticultural Plant Growth and Development, Agricultural and Rural Ministry of China, Zhejiang University, Hangzhou 310058, China.; School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston B15 2TT, United Kingdom.
ELONGATED HYPOCOTOYL5 (HY5) and PHYTOCHROME INTERACTING FACTORs (PIFs) are two types of important light-related regulators of plant growth, however, their interplay remains elusive. Here, we report that the activated tomato (Solanum lycopersicum) HY5 (SlHY5) triggers the transcription of a Calcium-dependent Protein Kinase SlCPK27. SlCPK27 interacts with and phosphorylates SlPIF4 at Ser-252 and Ser-308 phosphosites to promote its degradation. SlPIF4 promotes hypocotyl elongation mainly by activating the transcription of SlDWF, a key gene in brassinosteroid (BR) biosynthesis. Such a SlHY5-SlCPK27-SlPIF4-BR cascade not only plays a crucial role in photomorphogenesis but also regulates thermomorphogenesis. Our results uncover a previously unidentified mechanism that integrates Ca(2+) signaling with the light signaling pathways to regulate plant growth by modulating BR biosynthesis in response to changes in ambient light and temperature.
PMID: 39190354
Proc Natl Acad Sci U S A , IF:11.205 , 2024 Aug , V121 (33) : Pe2400862121 doi: 10.1073/pnas.2400862121
Leveraging coevolutionary insights and AI-based structural modeling to unravel receptor-peptide ligand-binding mechanisms.
Department of Plant and Microbial Biology (IPMB), Zurich-Basel Plant Science Center, University of Zurich, Zurich 8008, Switzerland.; The Plant Signaling Mechanisms Laboratory, Department of Plant Molecular Biology, University of Lausanne, Lausanne 1015, Switzerland.; MWSchmid GmbH, Glarus 8750, Switzerland.; The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
Secreted signaling peptides are central regulators of growth, development, and stress responses, but specific steps in the evolution of these peptides and their receptors are not well understood. Also, the molecular mechanisms of peptide-receptor binding are only known for a few examples, primarily owing to the limited availability of protein structural determination capabilities to few laboratories worldwide. Plants have evolved a multitude of secreted signaling peptides and corresponding transmembrane receptors. Stress-responsive SERINE RICH ENDOGENOUS PEPTIDES (SCOOPs) were recently identified. Bioactive SCOOPs are proteolytically processed by subtilases and are perceived by the leucine-rich repeat receptor kinase MALE DISCOVERER 1-INTERACTING RECEPTOR-LIKE KINASE 2 (MIK2) in the model plant Arabidopsis thaliana. How SCOOPs and MIK2 have (co)evolved, and how SCOOPs bind to MIK2 are unknown. Using in silico analysis of 350 plant genomes and subsequent functional testing, we revealed the conservation of MIK2 as SCOOP receptor within the plant order Brassicales. We then leveraged AI-based structural modeling and comparative genomics to identify two conserved putative SCOOP-MIK2 binding pockets across Brassicales MIK2 homologues predicted to interact with the "SxS" motif of otherwise sequence-divergent SCOOPs. Mutagenesis of both predicted binding pockets compromised SCOOP binding to MIK2, SCOOP-induced complex formation between MIK2 and its coreceptor BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED KINASE 1, and SCOOP-induced reactive oxygen species production, thus, confirming our in silico predictions. Collectively, in addition to revealing the elusive SCOOP-MIK2 binding mechanism, our analytic pipeline combining phylogenomics, AI-based structural predictions, and experimental biochemical and physiological validation provides a blueprint for the elucidation of peptide ligand-receptor perception mechanisms.
PMID: 39106311
New Phytol , IF:10.151 , 2024 Aug doi: 10.1111/nph.20055
RACK1 links phyB and BES1 to coordinate brassinosteroid-dependent root meristem development.
Shenzhen Key Laboratory of Plant Genetic Engineering and Molecular Design, Department of Biology, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen, 518055, China.
Light and brassinosteroids (BR) are indispensable for plant growth and control cell division in the apical meristem. However, how external light signals cooperate with internal brassinosteroids to program root meristem development remains elusive. We reveal that the photoreceptor phytochrome B (phyB) guides the scaffold protein RACK1 to coordinate BR signaling for maintaining root meristematic activity. phyB and RACK1 promote early root meristem development. Mechanistically, RACK1 could reinforce the phyB-SPA1 association by interacting with both phyB and SPA1, which indirectly affects COP1-dependent RACK1 degradation, resulting in the accumulation of RACK1 in roots. Subsequently, RACK1 interacts with BES1 to repress its DNA-binding activity toward the target gene CYCD3;1, leading to the release of BES1-mediated inhibition of CYCD3;1 transcription, and hence the promotion of root meristem development. Our study provides mechanistic insights into the regulation of root meristem development by combination of light and phytohormones signals through the photoreceptors and scaffold proteins.
PMID: 39149918
New Phytol , IF:10.151 , 2024 Aug , V243 (3) : P1050-1064 doi: 10.1111/nph.19903
The lncRNA1-miR6288b-3p-PpTCP4-PpD2 module regulates peach branch number by affecting brassinosteroid biosynthesis.
College of Horticulture, Henan Agricultural University, 218 Pingan Road, Zhengzhou, 450046, China.; Henan Engineering and Technology Center for Peach Germplasm Innovation and Utilization, Zhengzhou, 450046, China.; Henan Provincial International Joint Laboratory of Horticultural Crops, Zhengzhou, 450046, China.; College of Forestry, Henan Agricultural University, 218 Pingan Road, Zhengzhou, 450046, China.
Branch number is one of the most important agronomic traits of fruit trees such as peach. Little is known about how LncRNA and/or miRNA modules regulate branching through transcription factors. Here, we used molecular and genetic tools to clarify the molecular mechanisms underlying brassinosteroid (BR) altering plant branching. We found that the number of sylleptic branch and BR content in pillar peach ('Zhaoshouhong') was lower than those of standard type ('Okubo'), and exogenous BR application could significantly promote branching. PpTCP4 expressed great differentially comparing 'Zhaoshouhong' with 'Okubo'. PpTCP4 could directly bind to DWARF2 (PpD2) and inhibited its expression. PpD2 was the only one differentially expressed key gene in the path of BR biosynthesis. At the same time, PpTCP4 was identified as a target of miR6288b-3p. LncRNA1 could act as the endogenous target mimic of miR6288b-3p and repress expression of miR6288b-3p. Three deletions and five SNP sites of lncRNA1 promoter were found in 'Zhaoshouhong', which was an important cause of different mRNA level of PpTCP4 and BR content. Moreover, overexpressed PpTCP4 significantly inhibited branching. A novel mechanism in which the lncRNA1-miR6288b-3p-PpTCP4-PpD2 module regulates peach branching number was proposed.
PMID: 38872462
Plant Physiol , IF:8.34 , 2024 Jul , V195 (4) : P3072-3096 doi: 10.1093/plphys/kiae147
A maize semi-dwarf mutant reveals a GRAS transcription factor involved in brassinosteroid signaling.
Department of Biochemistry, Purdue University, West Lafayette, IN 47907USA.; Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA.; Plant Genetics Research Unit, USDA-ARS, Columbia, MO 65211, USA.; Institute for Molecular Physiology, Heinrich-Heine-Universitat Dusseldorf, 40225 Dusseldorf, Germany.; Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA.; Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, USA.
Brassinosteroids (BR) and gibberellins (GA) regulate plant height and leaf angle in maize (Zea mays). Mutants with defects in BR or GA biosynthesis or signaling identify components of these pathways and enhance our knowledge about plant growth and development. In this study, we characterized three recessive mutant alleles of GRAS transcription factor 42 (gras42) in maize, a GRAS transcription factor gene orthologous to the DWARF AND LOW TILLERING (DLT) gene of rice (Oryza sativa). These maize mutants exhibited semi-dwarf stature, shorter and wider leaves, and more upright leaf angle. Transcriptome analysis revealed a role for GRAS42 as a determinant of BR signaling. Analysis of the expression consequences from loss of GRAS42 in the gras42-mu1021149 mutant indicated a weak loss of BR signaling in the mutant, consistent with its previously demonstrated role in BR signaling in rice. Loss of BR signaling was also evident by the enhancement of weak BR biosynthetic mutant alleles in double mutants of nana plant1-1 and gras42-mu1021149. The gras42-mu1021149 mutant had little effect on GA-regulated gene expression, suggesting that GRAS42 is not a regulator of core GA signaling genes in maize. Single-cell expression data identified gras42 expressed among cells in the G2/M phase of the cell cycle consistent with its previously demonstrated role in cell cycle gene expression in Arabidopsis (Arabidopsis thaliana). Cis-acting natural variation controlling GRAS42 transcript accumulation was identified by expression genome-wide association study (eGWAS) in maize. Our results demonstrate a conserved role for GRAS42/SCARECROW-LIKE 28 (SCL28)/DLT in BR signaling, clarify the role of this gene in GA signaling, and suggest mechanisms of tillering and leaf angle control by BR.
PMID: 38709680
Plant Physiol , IF:8.34 , 2024 Jul , V195 (4) : P2712-2726 doi: 10.1093/plphys/kiae217
Jasmonate mimic modulates cell elongation by regulating antagonistic bHLH transcription factors via brassinosteroid signaling.
State Key Laboratory of Plant Environmental Resilience, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.; College of Plant Science and Technology, Beijing University of Agriculture, Beijing 102206, China.
Lodging restricts growth, development, and yield formation in maize (Zea mays L.). Shorter internode length is beneficial for lodging tolerance. However, although brassinosteroids (BRs) and jasmonic acid (JA) are known to antagonistically regulate internode growth, the underlying molecular mechanism is still unclear. In this study, application of the JA mimic coronatine (COR) inhibited basal internode elongation at the jointing stage and repressed expression of the cell wall-related gene XYLOGLUCAN ENDOTRANSGLUCOSYLASE/HYDROLASE 1 (ZmXTH1), whose overexpression in maize plants promoted internode elongation. We demonstrated that the basic helix-loop-helix (bHLH) transcription factor ZmbHLH154 directly binds to the ZmXTH1 promoter and induces its expression, whereas the bHLH transcription factor ILI1 BINDING BHLH 1 (ZmIBH1) inhibits this transcriptional activation by forming a heterodimer with ZmbHLH154. Overexpressing ZmbHLH154 led to longer internodes, whereas zmbhlh154 mutants had shorter internodes than the wild type. The core JA-dependent transcription factors ZmMYC2-4 and ZmMYC2-6 interacted with BRASSINAZOLE RESISTANT 1 (ZmBZR1), a key factor in BR signaling, and these interactions eliminated the inhibitory effect of ZmBZR1 on its downstream gene ZmIBH1. Collectively, these results reveal a signaling module in which JA regulates a bHLH network by attenuating BR signaling to inhibit ZmXTH1 expression, thereby regulating cell elongation in maize.
PMID: 38636101
BMC Biol , IF:7.431 , 2024 Aug , V22 (1) : P184 doi: 10.1186/s12915-024-01985-z
PmLBD3 links auxin and brassinosteroid signalling pathways on dwarfism in Prunus mume.
Laboratory of Fruit Tree Biotechnology, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, China.; College of Horticulture, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, China.; Laboratory of Fruit Tree Biotechnology, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, China. gaozhihong@njau.edu.cn.
BACKGROUND: Grafting with dwarf rootstock is an efficient method to control plant height in fruit production. However, the molecular mechanism remains unclear. Our previous study showed that plants with Prunus mume (mume) rootstock exhibited a considerable reduction in plant height, internode length, and number of nodes compared with Prunus persica (peach) rootstock. The present study aimed to investigate the mechanism behind the regulation of plant height by mume rootstocks through transcriptomic and metabolomic analyses with two grafting combinations, 'Longyan/Mume' and 'Longyan/Peach'. RESULTS: There was a significant decrease in brassinolide levels in plants that were grafted onto mume rootstocks. Plant hormone signal transduction and brassinolide production metabolism gene expression also changed significantly. Flavonoid levels, amino acid and fatty acid metabolites, and energy metabolism in dwarf plants decreased. There was a notable upregulation of PmLBD3 gene expression in plant specimens that were subjected to grafting onto mume rootstocks. Auxin signalling cues promoted PmARF3 transcription, which directly controlled this upregulation. Through its binding to PmBAS1 and PmSAUR36a gene promoters, PmLBD3 promoted endogenous brassinolide inactivation and inhibited cell proliferation. CONCLUSIONS: Auxin signalling and brassinolide levels are linked by PmLBD3. Our findings showed that PmLBD3 is a key transcription factor that regulates the balance of hormones through the auxin and brassinolide signalling pathways and causes dwarf plants in stone fruits.
PMID: 39183294
Int J Biol Macromol , IF:6.953 , 2024 Aug , V278 (Pt 3) : P134918 doi: 10.1016/j.ijbiomac.2024.134918
Alternaria solani core effector Aex59 is a new member of the Alt a 1 protein family and is recognized as a PAMP.
Department of Plant Pathology, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui 230036, China.; Department of Plant Pathology, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui 230036, China; Anhui Province Key Laboratory of Integrated Pest Management on Crops, Hefei, Anhui 230036, China.; Department of Plant Pathology, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui 230036, China; Anhui Province Key Laboratory of Integrated Pest Management on Crops, Hefei, Anhui 230036, China. Electronic address: zliu@ahau.edu.cn.
Early blight caused by Alternaria solani is a destructive disease in potato production. Here, through systematically screening of an effector protein pool consisting of 115 small cysteine-containing candidate Aex (Alternariaextracellular proteins) in A. solani, we identified a core effector protein named Aex59, a pathogen-associated molecular pattern (PAMP) molecule. Aex59 is uniquely present in the Ascomycota of fungi and can activate defense responses in multiple plants. Targeted gene disruption showed that Aex59 is a virulence factor and participates in spore development. Perception of Aex59 in Nicotiana benthamiana does not depend on the receptor-like kinases Brassinosteroid-associated kinase1 (BAK1) and Suppressor of BIR1-1 (SOBIR1), which are required for multiple pattern recognition receptors (PRR) pathways. Sequence analysis revealed that Aex59 is a new member of the Alt a 1 protein family and is a potential molecular marker capable of aiding in the classification of the fungi Alternaria spp.
PMID: 39179073
J Environ Manage , IF:6.789 , 2024 Aug , V366 : P121825 doi: 10.1016/j.jenvman.2024.121825
Effects of N, N-bis (carboxymethyl)-L-glutamic acid and polyaspartic acid on the phytoremediation of cadmium in contaminated soil at the presence of pyrene: Biochemical properties and transcriptome analysis.
College of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China. Electronic address: xqy010413@163.com.; College of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China; Shanghai Huali Integrated Circuit Manufacturing Co., LTD, Shanghai, 201317, China.; State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200241, China.; College of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China. Electronic address: zxyshu@shu.edu.cn.; College of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China. Electronic address: lxy999@shu.edu.cn.; College of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, Shanghai, 200444, China.; Ecological Environment Monitoring and Scientific Research Center, Taihu Basin & East China Sea Ecological Environment Supervision and Administration Bureau, Ministry of Ecology and Environment, Shanghai, 200125, China.
Chelator-assisted phytoremediation is an efficacious method for promoting the removal efficiency of heavy metals (HMs). The effects of N, N-bis(carboxymethyl)-L-glutamic acid (GLDA) and polyaspartic acid (PASP) on Cd uptake and pyrene removal by Solanum nigrum L. (S. nigrum) were compared in this study. Using GLDA or PASP, the removal efficiency of pyrene was over 98%. And PASP observably raised the accumulation and transport of Cd by S. nigrum compared with GLDA. Meanwhile, both GLDA and PASP markedly increased soil dehydrogenase activities (DHA) and microbial activities. DHA and microbial activities in the PASP treatment group were 1.05 and 1.06 folds of those in the GLDA treatment group, respectively. Transcriptome analysis revealed that 1206 and 1684 differentially expressed genes (DEGs) were recognized in the GLDA treatment group and PASP treatment group, respectively. Most of the DEGs found in the PASP treatment group were involved in the metabolism of carbohydrates, the biosynthesis of brassinosteroid and flavonoid, and they were up-regulated. The DEGs related to Cd transport were screened, and ABCG3, ABCC4, ABCG9 and Nramp5 were found to be relevant with the reduction of Cd stress in S. nigrum by PASP. Furthermore, with PASP treated, transcription factors (TFs) related to HMs such as WRKY, bHLH, AP2/ERF, MYB were down-regulated, while more MYB and bZIP TFs were up-regulated. These TFs associated with plant stress resistance would work together to induce oxidative stress. The above results indicated that PASP was more conducive for phytoremediation of Cd-pyrene co-contaminated soil than GLDA.
PMID: 38996604
Plant J , IF:6.417 , 2024 Aug doi: 10.1111/tpj.16968
BRASSINOSTEROID-SIGNALING KINASE 1 modulates OPEN STOMATA 1 phosphorylation and contributes to stomatal closure and plant immunity.
State Key Laboratory of Ecological Control of Fujian-Taiwan Crop Pests, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.; Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.; College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Stomatal movement plays a critical role in plant immunity by limiting the entry of pathogens. OPEN STOMATA 1 (OST1) is a key component that mediates stomatal closure in plants, however, how OST1 functions in response to pathogens is not well understood. RECEPTOR-LIKE KINASE 902 (RLK902) phosphorylates BRASSINOSTEROID-SIGNALING KINASE 1 (BSK1) and positively modulates plant resistance. In this study, by a genome-wide phosphorylation analysis, we found that the phosphorylation of BSK1 and OST1 was missing in the rlk902 mutant compared with the wild-type plants, indicating a potential connection between the RLK902-BSK1 module and OST1-mediated stomatal closure. We showed that RLK902 and BSK1 contribute to stomatal immunity, as the stomatal closure induced by the bacterial pathogen Pto DC3000 was impaired in rlk902 and bsk1-1 mutants. Stomatal immunity mediated by RLK902 was dependent on BSK1 phosphorylation at Ser230, a key phosphorylation site for BSK1 functions. Several phosphorylation sites of OST1 were important for RLK902- and BSK1-mediated stomatal immunity. Interestingly, the phosphorylation of Ser171 and Ser175 in OST1 contributed to the stomatal immunity mediated by RLK902 but not by BSK1, while phosphorylation of OST1 at Ser29 and Thr176 residues was critical for BSK1-mediated stomatal immunity. Taken together, these results indicate that RLK902 and BSK1 contribute to disease resistance via OST1-mediated stomatal closure. This work revealed a new function of BSK1 in activating stomatal immunity, and the role of RLK902-BSK1 and OST1 module in regulating pathogen-induced stomatal movement.
PMID: 39126292
Plant J , IF:6.417 , 2024 Aug , V119 (3) : P1353-1368 doi: 10.1111/tpj.16855
A multifaceted crosstalk between brassinosteroid and gibberellin regulates the resistance of cucumber to Phytophthora melonis.
College of Horticulture, South China Agricultural University, Guangzhou, P. R. China.
Cucumber plants are highly susceptible to the hemibiotroph oomycete Phytophthora melonis. However, the mechanism of resistance to cucumber blight remains poorly understood. Here, we demonstrated that cucumber plants with impairment in the biosynthesis of brassinosteroids (BRs) or gibberellins (GAs) were more susceptible to P. melonis. By contrast, increasing levels of endogenous BRs or exogenously application of 24-epibrassinolide enhanced the resistance of cucumber plants against P. melonis. Furthermore, we found that both knockout and overexpression of the BR biosynthesis gene CYP85A1 reduced the endogenous GA(3) content compared with that of wild-type plants under the condition of inoculation with P. melonis, and the enhancement of disease resistance conferred by BR was inhibited in plants with silencing of the GA biosynthetic gene GA20ox1 or KAO. Together, these findings suggest that GA homeostasis is an essential factor mediating BRs-induced disease resistance. Moreover, BZR6, a key regulator of BR signaling, was found to physically interact with GA20ox1, thereby suppressing its transcription. Silencing of BZR6 promoted endogenous GA biosynthesis and compromised GA-mediated resistance. These findings reveal multifaceted crosstalk between BR and GA in response to pathogen infection, which can provide a new approach for genetically controlling P. melonis damage in cucumber production.
PMID: 38829920
Int J Mol Sci , IF:5.923 , 2024 Aug , V25 (15) doi: 10.3390/ijms25158499
Genome-Wide Identification of the Brassinosteroid Signal Kinase Gene Family and Its Profiling under Salinity Stress.
College of Agriculture, Tarim University, Alar 843300, China.; CAS Engineering Laboratory for Grass-Based Livestock Husbandry, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.; Biotechnology Research Institute, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi 832000, China.
Alfalfa (Medicago L.) is a high-quality perennial leguminous forage with the advantages of salt tolerance, mowing tolerance, high protein content, and other economically valuable characteristics. As the sixth class of plant hormones, brassinosteroids (BRs) play indispensable roles in modulating a variety of plant growth, maturation, and environmental adaptation processes, thereby influencing vegetal expansion and development. Brassinosteroid signal kinases (BSKs) are key cytoplasmic receptor kinases downstream of the BR signaling transduction pathway, participating in plant growth, development, and stress regulation. However, the phylogenetic and expression pattern analyses of the BSK gene family among the five alfalfa species have rarely been reported; in this study, 52 BSK family members were found in the genomes of the five subspecies, and phylogenetic trees were constructed according to protein sequences, allowing us to categorize all BSKs into seven distinct groups. Domain, conserved motif, and exon-intron structural analyses showed that most BSK members were relatively conserved, except for MtBSK3-2, MtBSK7-1, and MtBSK7-2, which may be truncated members. Intra-species collinearity and Ka/Ks analyses showed that purifying selection influenced BSK genes during evolution; most of the cis-acting elements in the promoter region were associated with responses, such as light, defense, and stress, anaerobic induction, MeJA, and abscisic acid. Expression pattern analysis indicated that the majority of alfalfa genes exhibited downregulation after reaching a peak at 0.5 h after treatment with 250 mM NaCl, especially for MsBSK14, MsBSK15, MsBSK17, MsBSK19, and MsBSK21; meanwhile, MsBSK4, MsBSK7, and MsBSK9 increased and were highly expressed at 12 h, demonstrating significantly altered expression patterns under salt stress; furthermore, MsBSK4, MsBSK7, and MsBSK9 exhibited expression specifically in the leaves. qRT-PCR analysis confirmed the expression trends for MsBSK4, MsBSK7, MsBSK9, MsBSK14, MsBSK15, and MsBSK16 matched the transcriptome data. However, the trends for MsBSK17, MsBSK19, and MsBSK21 diverged from the transcriptome data. Our study may provide a foundation for further functional analyses of BSK genes in growth, development, and salt stress tolerance in alfalfa.
PMID: 39126068
J Agric Food Chem , IF:5.279 , 2024 Aug , V72 (34) : P19219-19231 doi: 10.1021/acs.jafc.4c02650
Global Characterization of DNA Methylation during Rice Leaf Angle Development.
Key Laboratory of Three Gorges Regional Plant Genetics and Germplasm Enhancement (CTGU)/Biotechnology Research Center, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
During plant development and growth, genomic DNA accumulates chemical markers that determine the levels of gene expression. DNA methylation is an important epigenetic marker involved in plant developmental events. However, the characterization of the role of DNA methylation in rice leaf angle development has lagged behind. Herein, we performed bisulfite sequencing to characterize DNA methylation sites and performed transcriptome and small RNA sequencing during leaf angle development. The results revealed a global reduction in CG methylation during leaf angle establishment. A reduction in gene body CG methylation appears to play a vital role in leaf angle development. The hypomethylated and weakly expressed genes were functionally enriched in the brassinosteroid and auxin signaling pathways. Additionally, the main DNA methyltransferases were inactive. The addition of exogenous DNA methylation inhibitor 5-azacytidine increased the leaf angle, which confirmed that DNA methylation is crucial for leaf angle development. This study revealed a gradual decrease in 24-nucleotide siRNA levels during leaf angle development, particularly in relation to the enrichment of 24-nucleotide siRNAs at different hypomethylated regions that induce leaf angle inclination. Our results indicate crucial roles for DNA methylation in the rice leaf angle developmental stages.
PMID: 39146245
Sci Rep , IF:4.379 , 2024 Aug , V14 (1) : P18278 doi: 10.1038/s41598-024-69373-9
The cap-binding complex modulates ABA-responsive transcript splicing during germination in barley (Hordeum vulgare).
Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Jagiellonska 28, 40-032, Katowice, Poland.; Department of Life Science, Aberystwyth University, Aberystwyth, UK.; Information and Computational Sciences, James Hutton Institute, Dundee, DD2 5DA, Scotland, UK.; Cell and Molecular Sciences, James Hutton Institute, Dundee, DD2 5DA, Scotland, UK.; Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Jagiellonska 28, 40-032, Katowice, Poland. agata.daszkowska@us.edu.pl.
To decipher the molecular bases governing seed germination, this study presents the pivotal role of the cap-binding complex (CBC), comprising CBP20 and CBP80, in modulating the inhibitory effects of abscisic acid (ABA) in barley. Using both single and double barley mutants in genes encoding the CBC, we revealed that the double mutant hvcbp20.ab/hvcbp80.b displays ABA insensitivity, in stark contrast to the hypersensitivity observed in single mutants during germination. Our comprehensive transcriptome and metabolome analysis not only identified significant alterations in gene expression and splicing patterns but also underscored the regulatory nexus among CBC, ABA, and brassinosteroid (BR) signaling pathways.
PMID: 39107424
BMC Plant Biol , IF:4.215 , 2024 Aug , V24 (1) : P737 doi: 10.1186/s12870-024-05453-2
Genome-wide identification of Brassinosteroid insensitive 1-associated receptor kinase 1 genes and expression analysis in response to pathogen infection in cucumber (Cucumis sativus L.).
State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.; State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. miaohan@caas.cn.; State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. zhangshengping@caas.cn.
BACKGROUND: BAK1 (Brassinosteroid insensitive 1-associated receptor kinase 1) plays an important role in disease resistance in plants. However, the function of BAK1 family in cucumber and the decisive genes for disease-resistance remain elusive. RESULTS: Here, we identified 27 CsBAK1s in cucumber, and classified them into five subgroups based on phylogenetic analysis and gene structure. CsBAK1s in the same subgroup shared the similar motifs, but different gene structures. Cis-elements analysis revealed that CsBAK1s might respond to various stress and growth regulation. Three segmentally duplicated pairwise genes were identified in cucumber. In addition, Ka/Ks analysis indicated that CsBAK1s were under positive selection during evolution. Tissue expression profile showed that most CsBAK1s in Subgroup II and IV showed constitutive expression, members in other subgroups showed tissue-specific expression. To further explore whether CsBAK1s were involved in the resistance to pathogens, the expression patterns of CsBAK1s to five pathogens (gummy stem blight, powdery mildew, downy mildew, grey mildew, and fusarium wilt) reveled that different CsBAK1s had specific roles in different pathogen infections. The expression of CsBAK1-14 was induced/repressed significantly by five pathogens, CsBAK1-14 might play an important role in disease resistance in cucumber. CONCLUSIONS: 27 BAK1 genes were identified in cucumber from a full perspective, which have important functions in pathogen infection. Our study provided a theoretical basis to further clarify the function of BAK1s to disease resistance in cucumber.
PMID: 39095762
BMC Plant Biol , IF:4.215 , 2024 Aug , V24 (1) : P734 doi: 10.1186/s12870-024-05442-5
Overexpression of MtIPT gene enhanced drought tolerance and delayed leaf senescence of creeping bentgrass (Agrostis stolonifera L.).
School of Grassland Science of Beijing Forestry University, Beijing, China.; Engineering and Technology Research Center for Sports Field and Slope Protection Turf, National Forestry and Grassland Administration, Beijing, China.; UWA School of Agriculture and Environment, The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, Australia.; Shenzhen Tidyfield System Biotechnology Co., Ltd, Shenzhen, China.; College of Agronomy, State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Crop Growth Regulation of Hebei Province, Hebei Agricultural University, Baoding, China.; School of Grassland Science of Beijing Forestry University, Beijing, China. hanliebao@163.com.; Engineering and Technology Research Center for Sports Field and Slope Protection Turf, National Forestry and Grassland Administration, Beijing, China. hanliebao@163.com.; School of Grassland Science of Beijing Forestry University, Beijing, China. chaoyuehui@bjfu.edu.cn.; Engineering and Technology Research Center for Sports Field and Slope Protection Turf, National Forestry and Grassland Administration, Beijing, China. chaoyuehui@bjfu.edu.cn.
BACKGROUND: Isopentenyltransferases (IPT) serve as crucial rate-limiting enzyme in cytokinin synthesis, playing a vital role in plant growth, development, and resistance to abiotic stress. RESULTS: Compared to the wild type, transgenic creeping bentgrass exhibited a slower growth rate, heightened drought tolerance, and improved shade tolerance attributed to delayed leaf senescence. Additionally, transgenic plants showed significant increases in antioxidant enzyme levels, chlorophyll content, and soluble sugars. Importantly, this study uncovered that overexpression of the MtIPT gene not only significantly enhanced cytokinin and auxin content but also influenced brassinosteroid level. RNA-seq analysis revealed that differentially expressed genes (DEGs) between transgenic and wild type plants were closely associated with plant hormone signal transduction, steroid biosynthesis, photosynthesis, flavonoid biosynthesis, carotenoid biosynthesis, anthocyanin biosynthesis, oxidation-reduction process, cytokinin metabolism, and wax biosynthesis. And numerous DEGs related to growth, development, and stress tolerance were identified, including cytokinin signal transduction genes (CRE1, B-ARR), antioxidase-related genes (APX2, PEX11, PER1), Photosynthesis-related genes (ATPF1A, PSBQ, PETF), flavonoid synthesis genes (F3H, C12RT1, DFR), wax synthesis gene (MAH1), senescence-associated gene (SAG20), among others. CONCLUSION: These findings suggest that the MtIPT gene acts as a negative regulator of plant growth and development, while also playing a crucial role in the plant's response to abiotic stress.
PMID: 39085786
Planta , IF:4.116 , 2024 Aug , V260 (3) : P74 doi: 10.1007/s00425-024-04507-x
Phenotypic and transcriptomics characterization uncovers genes underlying tuber yield traits and gene expression marker development in potato under aeroponics.
Indian Council of Agricultural Research-Central Potato Research Institute, Shimla, Himachal Pradesh, India.; School of Bioengineering and Biosciences, Lovely Professional University, Phagwara, Punjab, India.; Indian Council of Agricultural Research-Central Potato Research Institute, Shimla, Himachal Pradesh, India. jagesh.kumar@icar.gov.in.; Indian Council of Agricultural Research- Indian Institute of Vegetable Research, Varanasi, Uttar Pradesh, India. jagesh.kumar@icar.gov.in.; Indian Council of Agricultural Research- Indian Institute of Vegetable Research, Varanasi, Uttar Pradesh, India.
Transcriptome analysis in potato varieties revealed genes associated with tuber yield-related traits and developed gene expression markers. This study aimed to identify genes involved in high tuber yield and its component traits in test potato varieties (Kufri Frysona, Kufri Khyati, and Kufri Mohan) compared to control (Kufri Sutlej). The aeroponic evaluation showed significant differences in yield-related traits in the varieties. Total RNA sequencing was performed using tuber and leaf tissues on the Illumina platform. The high-quality reads (QV > 25) mapping with the reference potato genomes revealed statistically significant (P < 0.05) differentially expressed genes (DEGs) into two categories: up-regulated (> 2 Log(2) fold change) and down-regulated (< -2 Log(2) fold change). DEGs were characterized by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Collectively, we identified genes participating in sugar metabolism, stress response, transcription factors, phytohormones, kinase proteins, and other genes greatly affecting tuber yield and its related traits. A few selected genes were UDP-glucose glucosyltransferase, glutathion S-transferase, GDSL esterase/lipase, transcription factors (MYB, WRKY, bHLH63, and BURP), phytohormones (auxin-induced protein X10A, and GA20 oxidase), kinase proteins (Kunitz-type tuber invertase inhibitor, BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1) and laccase. Based on the selected 17 peptide sequences representing 13 genes, a phylogeny tree and motifs were analyzed. Real time-quantitative polymerase chain reaction (RT-qPCR) analysis was used to validate the RNA-seq results. RT-qPCR based gene expression markers were developed for the genes such as 101 kDa heat shock protein, catechol oxidase B chloroplastic, cysteine protease inhibitor 1, Kunitz-type tuber invertase inhibitor, and laccase to identify high yielding potato genotypes. Thus, our study paved the path for potential genes associated with tuber yield traits in potato under aeroponics.
PMID: 39153022
Plants (Basel) , IF:3.935 , 2024 Aug , V13 (16) doi: 10.3390/plants13162308
Co-Expression Network Analysis and Introgressive Gene Identification for Fiber Length and Strength Reveal Transcriptional Differences in 15 Cotton Chromosome Substitution Segment Lines and Their Upland and Sea Island Parents.
School of Biotechnology and Food Engineering, Anyang Institute of Technology, Anyang 455000, China.; National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, Institute of Cotton Research of Chinese Academy of Agricultural Sciences, Anyang 455000, China.; National Key Laboratory of Cotton Bio-Breeding and Integrated Utilization, Zhengzhou University, Zhengzhou 450001, China.; Xinjiang Production and Construction Corps Seventh Division Agricultural Research Institute, Kuitun 833200, China.; Agricultural Technology Popularization Center of Kashgar, Kashgar 844000, China.
Fiber length (FL) and strength (FS) are the core indicators for evaluating cotton fiber quality. The corresponding stages of fiber elongation and secondary wall thickening are of great significance in determining FL and FS formation, respectively. QTL mapping and high-throughput sequencing technology have been applied to dissect the molecular mechanism of fiber development. In this study, 15 cotton chromosome segment substitution lines (CSSLs) with significant differences in FL and FS, together with their recurrent parental Gossypium hirsutum line CCRI45 and donor parent G. barbadense line Hai1, were chosen to conduct RNA-seq on developing fiber samples at 10 days post anthesis (DPA) and 20 DPA. Differentially expressed genes (DEGs) were obtained via pairwise comparisons among all 24 samples (each one with three biological repeats). A total of 969 DEGs related to FL-high, 1285 DEGs to FS-high, and 997 DEGs to FQ-high were identified. The functional enrichment analyses of them indicated that the GO terms of cell wall structure and ROS, carbohydrate, and phenylpropanoid metabolism were significantly enriched, while the GO terms of glucose and polysaccharide biosynthesis, and brassinosteroid and glycosylphosphatidylinositol metabolism could make great contributions to FL and FS formation, respectively. Weighted gene co-expressed network analyses (WGCNA) were separately conducted for analyzing FL and FS traits, and their corresponding hub DEGs were screened in significantly correlated expression modules, such as EXPA8, XTH, and HMA in the fiber elongation and WRKY, TDT, and RAC-like 2 during secondary wall thickening. An integrated analysis of these hub DEGs with previous QTL identification results successfully identified a total of 33 candidate introgressive DEGs with non-synonymous mutations between the Gh and Gb species. A common DEG encoding receptor-like protein kinase 1 was reported to likely participate in fiber secondary cell thickening regulation by brassionsteroid signaling. Such valuable information was conducive to enlightening the developing mechanism of cotton fiber and also provided an abundant gene pool for further molecular breeding.
PMID: 39204744
Biochem Biophys Res Commun , IF:3.575 , 2024 Sep , V723 : P150222 doi: 10.1016/j.bbrc.2024.150222
Brassinosteroid-signaling kinase ZmBSK7 enhances salt stress tolerance in maize.
College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.; College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China; State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, 210095, China. Electronic address: ayzhang@njau.edu.cn.
Salinity has become a crucial environmental factor that restricts plant growth, development, and productivity. Nevertheless, the mechanisms by which plants react to salt stress remain inadequately comprehended. In this study, we identified maize brassinosteroid-signaling kinase gene ZmBSK7 which is homologous to AtBSK1. Our results showed that ZmBSK7 is induced by salt stress and ZmBSK7 localizes in the plasma membrane. ZmBSK7 overexpression increases salt tolerance, while its knockdown decreases salt tolerance in maize. ZmBSK7 reduces the malondialdehyde (MDA) content and the percentage of electrolyte leakage, and also elevates the activities of antioxidant enzymes. Furthermore, ZmBSK7 promotes K(+) content accumulation and reduces Na(+)/K(+) ratio. Further found that ZmBSK7 physically interacts with K(+) efflux antiporter 2 (ZmKEA2) in vivo and in vitro. Salt stress also increased the expression of ZmKEA2. Thus, ZmBSK7 improves salt tolerance in maize by affecting ZmKEA2 expression to promote K(+) content accumulation and reduce Na(+)/K(+) ratio. This study enhances the comprehension of BSK proteins and establishes a theoretical foundation for investigating salt stress tolerance in plants.
PMID: 38850813
J Plant Physiol , IF:3.549 , 2024 Oct , V301 : P154304 doi: 10.1016/j.jplph.2024.154304
Modulation of plant polyamine and ethylene biosynthesis; and brassinosteroid signaling during Bacillus endophyticus J13-mediated salinity tolerance in Arabidopsis thaliana.
Department of Biological Sciences, Birla Institute of Technology and Science Pilani, Hyderabad Campus, Hyderabad, Telangana, India.; Department of Biological Sciences, Birla Institute of Technology and Science Pilani, Hyderabad Campus, Hyderabad, Telangana, India. Electronic address: sridev.mohapatra@hyderabad.bits-pilani.ac.in.
Salinity stress adversely impacts plant growth and development. Plant growth-promoting rhizobacteria (PGPR) are known to confer salinity stress tolerance in plants through several mechanisms. Here, we report the role of an abiotic stress-tolerant PGPR strain, Bacillus endophyticus J13, in promoting salinity stress tolerance in Arabidopsis thaliana, by elucidating its impact on physiological responses, polyamine (PA) and ethylene biosynthesis, and brassinosteroid signaling. Physiological analysis revealed that J13 can significantly improve the overall plant growth under salt stress by increasing the biomass, relative water content, and chlorophyll content, decreasing membrane damage and lipid peroxidation, and modulating proline homeostasis in plants. Evaluation of shoot polyamine levels upon J13 inoculation revealed an overall decrease in the levels of the three major PAs, putrescine (Put), spermidine (Spd), and spermine (Spm), under non-stressed conditions. Salt stress significantly increased the levels of Put and Spm, while decreasing the Spd levels in the plants. J13 inoculation under salt-stressed conditions, significantly decreased the Put levels, bringing them closer to those of the untreated control plants, whereas Spd and Spm levels did not change relative to the non-inoculated salt-stressed plants. The modulation of PA levels was accompanied by changes in the expressions of key PA biosynthetic genes under all treatments. Among the ethylene biosynthetic genes that we studied, ACS1 was induced by J13 inoculation under salt stress. J13 inoculation under salt stress resulted in the modulation of the expressions of BR-signaling genes, upregulating the expressions of the positive regulators of BR-signaling (BZR1 and BES2) and downregulating that of the negative regulator (BIN2). Our results provide a new avenue for J13-mediated salt stress amelioration in Arabidopsis, via tight control of polyamine and ethylene biosynthesis and enhanced brassinosteroid signaling.
PMID: 38991234
Food Sci Nutr , IF:2.863 , 2024 Aug , V12 (8) : P6022-6033 doi: 10.1002/fsn3.4233
Physiological and biochemical characteristics of milk thistle (Silybum marianum (L.) Gaertn) as affected by some plant growth regulators.
Department of Horticultural Science University Campus 2, University of Guilan Rasht Iran.; Faculty of Agricultural Sciences, Department of Horticultural Science University of Guilan Rasht Iran.; Department of Research Center on Cultivation & Domestication of Medicinal Plants Agricultural Research Education and Extension Organization (AREEO) Karaj Iran.
Milk thistle (Silybum marianum (L.) Gaertn) is a globally and widely used medicinal plant that contains silymarin. This plant has antioxidant, antimicrobial, anticancer, hepatoprotective, cardiovascular-protective, and neuroprotective effects. Plant quality, yield, and phytochemicals, especially silymarin content, change under various conditions like drought stress. Therefore, this research studied plant growth regulators (PGRs) like salicylic acid, spermidine, and brassinosteroid to increase plant tolerance to drought stress. Experimental treatments include different levels of irrigation (25%, 50%, 75%, and 90% field capacity), and foliar spraying including salicylic acid (75 and 150 mg/L), spermine (70 and 140 mg/L), and brassinosteroid (1 and 1.2 muM), separately, and water as a control and a secondary factor. The results revealed that the highest amount of leaf phenolic compounds was observed in the highest drought stress level (25%) and 75 mg/L salicylic acid application. Furthermore, brassinosteroid at different concentrations and salicylic acid (75 mg/L) increased leaf flavonoid content compared to other treatments. In 50% field capacity, foliar application of salicylic acid (150 mg/L) significantly increased seed yield by approximately 75% compared to control under the same stress level. Brassinosteroid application (1 muM) under 75% field capacity significantly increased the seed's taxifolin amount by 159%. Additionally, salicylic acid noticeably increased the silychristin concentration. The concentration of silydianin in the seed has also been increased under drought stress and foliar spraying with PGRs. Compared to the control, using spermidine below 75% field capacity caused an increase in its concentrations by over seven times. The highest silybin A amount was obtained in 50% field capacity and foliar150 mg/L salicylic acid. Taxifolin, silychristin, silydianin, silybinin B, iso-silybinin A, and iso-silybinin B compounds were identified in the seed extract. Generally, foliar spraying using plant growth regulators increased the number of silymarin compounds under drought stress conditions and field cultivation conditions.
PMID: 39139968