The rapid elongation of rice(Oryza sativa)coleoptile is pivotal for the plant plumule to evade hypoxia stress induced by submergence,a condition often arising from overirrigation,ponding,rainstorms,or flooding.While b...The rapid elongation of rice(Oryza sativa)coleoptile is pivotal for the plant plumule to evade hypoxia stress induced by submergence,a condition often arising from overirrigation,ponding,rainstorms,or flooding.While brassinosteroids(BRs)are recognized for their diverse roles in plant growth and development,their influence on coleoptile elongation under hypoxic conditions remains largely unexplored.In this study,we demonstrate the significant requirement of BRs for coleoptile elongation in deep water.During coleoptile development,Glycogen Synthase Kinase3-Like Kinase2(GSK2),the central inhibitor of BR signaling in rice,undergoes substantial suppression in deep water but induction in air.In contrast,the dephosphorylated form of BRASSINAZOLE RESISTANT1(OsBZR1),representing the active form of the key BR signaling transcription factor,is induced in water but suppressed in air.Remarkably,the knockout of GSK3-like kinase genes significantly enhances coleoptile elongation in deep water,strongly indicating a vital contribution of BR response to hypoxia-stimulated coleoptile elongation.Transcriptome analysis uncovers both BR-associated and BR-independent hypoxia responses,implicating substance metabolism,redox reactions,abiotic stress responses,and crosstalk with other hormones in the regulation of BR-induced hypoxia responses.In summary,our findings suggest that rice plumules rapidly elongate coleoptiles through the activation of BR response in deep water,enabling them to escape from submergence-induced hypoxia stress.展开更多
Brassinosteroids(BRs)play critical roles in a wide range of plant developmental processes.However,it is unknown whether and how BRs mediate the effect of high temperature(HT)stress during anthesis on the pistil activi...Brassinosteroids(BRs)play critical roles in a wide range of plant developmental processes.However,it is unknown whether and how BRs mediate the effect of high temperature(HT)stress during anthesis on the pistil activity of photo-thermosensitive genetic male-sterile(PTSGMS)rice(Oryza sativa L.)lines.This study investigated the question.Three pot-grown PTSGMS rice lines were subjected to HT stress during anthesis.The contents of 24-epibrassinolide(24-EBL)and 28-homobrassinolide(28-HBL),the major forms of BR in rice plants,and levels of reactive oxygen species(ROS)or antioxidants(AOS),hydrogen peroxide(H2O2),1-aminocylopropane-1-carboxylic acid(ACC),ascorbic acid(AsA),and catalase activity in pistils,were determined.HT stress significantly reduced the contents of both 24-EBL and 28-EBL relative to those under normal temperatures,but the reduction varied by PTSGMS line.A line with higher BR contents under HT stress showed lower contents of ACC and H2O2,higher catalase activity and AsA content in pistils,and higher fertilization rate,seed-setting rate,and seed yield when the line was crossed with a restorer line,indicating that higher levels of BRs increase HT stress resistance.Applying 24-EBL,28-HBL or an inhibitor of BR biosynthesis confirmed the roles of BRs in response to HT stress.The results suggest that BRs mediate the effect of HT stress on pistil activity during anthesis and alleviate the harm of HT stress by increasing AOS and suppressing ROS generation.展开更多
High temperature (HT) stress has become one of the most detrimental stresses in crop production among constantly changing environmental factors.Exploiting approaches to enhance crop thermotolerance would have great si...High temperature (HT) stress has become one of the most detrimental stresses in crop production among constantly changing environmental factors.Exploiting approaches to enhance crop thermotolerance would have great significance in assuaging adverse effects of HT stress on crop growth and development.As jasmonates (JAs) and brassinosteroids (BRs) are novel phytohormones and play important roles in responses to biotic and abiotic stresses and in a wide range of plant developmental processes,this paper reviewed the roles and mechanisms of JAs and BRs in mitigating HT stress,with focus on rice (Oryza sativa L.) subjected to HT stress during anthesis.It is demonstrated that JAs alleviate spikelet-opening impairment and BRs ameliorate pistil fertilization ability under HT stress during anthesis of rice,although there are controversial observations.Activating the defense system,enhancing osmotic regulation,protecting photosynthesis,and interacting with other phytohormones,especially with ethylene and abscisic acid,are main physiological mechanisms by which JAs or BRs attenuate HT stress to plants.Elevating levels of JAs or BRs in plants could be considered as an important approach to enhance crop thermotolerance through breeding new varieties.Using JAs or BRs as chemical regulators and adopting proper water and nitrogen management practices could reduce the harm of HT stress to rice.Further research is needed to elucidate the roles of JAs and BRs in different plant tissues in responses to HT stress under different genetic backgrounds and environments,reveal the molecular mechanism underlying JAs and BRs mediating HT stress,understand the cross-talk between phytohormones in modulating HT stress,and establish integrated crop management to minimize the hazard of HT stress in rice production.展开更多
Brassinosteroids(BRs)are steroid hormones that function in plant growth and development and response to environmental stresses and nutrient supplies.However,few studies have investigated the effect of BRs in modulatin...Brassinosteroids(BRs)are steroid hormones that function in plant growth and development and response to environmental stresses and nutrient supplies.However,few studies have investigated the effect of BRs in modulating the physiological response to nitrogen(N)supply in maize.In the present study,BR signalingdeficient mutant zmbri1-RNAi lines and exogenous application of 2,4-epibrassinolide(e BL)were used to study the role of BRs in the regulation of physiological response in maize seedlings supplied with N.Exogenous application of e BL increased primary root length and plant biomass,but zmbri1 plants showed shorter primary roots and less plant biomass than wild-type plants under low N(LN)and normal N(NN)conditions.LN induced the expression of the BR signaling-associated genes Zm DWF4,Zm CPD,Zm DET2,and Zm BZR1 and the production of longer primary roots than NN.Knockdown of Zm BRI1 weakened the biological effects of LN-induced primary root elongation.e BL treatment increased N accumulation in shoots and roots of maize seedlings exposed to LN or NN treatment.Correspondingly,zmbri1 plants showed lower N accumulation in shoots and roots than wild-type plants.Along with reduced N accumulation,zmbri1 plants showed lower NO3-fluxes and^(15)NO_(3)^(-)uptake.The expression of nitrate transporter(NRT)genes(Zm NPF6.4,Zm NPF6.6,Zm NRT2.1,Zm NRT2.2)was lower in zmbri1 than in wild-type roots,but e BL treatments up-regulated the transcript expression of NRT genes.Thus,BRs modulated N physiological response and regulated the transcript expression of NRT genes to promote N uptake in maize.展开更多
Soil contamination with heavy metals has become a world-wide problem, leading to the loss in agricultural productivity. Plants have a remarkable ability to take up and accumulate heavy metals from their external envir...Soil contamination with heavy metals has become a world-wide problem, leading to the loss in agricultural productivity. Plants have a remarkable ability to take up and accumulate heavy metals from their external environment and it is well known that high levels of heavy metals affect different physiological and metabolic processes. Brassinosteroids are considered as the sixth class of plant hormones and they are essential for plant growth and development. These compounds are able of inducing abiotic stress tolerance in plants. In this paper, information about brassinosteroids and plant responses to heavy metal stress is reviewed.展开更多
Long developmental stage and late harvest time of winter rapeseed (Brassica napus L.) have great negative effects on rice planting of rice-rapeseed farming system in China. Early maturity improvement of rapeseed is ne...Long developmental stage and late harvest time of winter rapeseed (Brassica napus L.) have great negative effects on rice planting of rice-rapeseed farming system in China. Early maturity improvement of rapeseed is necessary. ‘Zhongshuang 11’, an elite winter rapeseed cultivar, was used in consecutive field experiments during 2010-2012. At initial flowering stage, plants were consecutively sprayed with 0.1 mg/L 2-4-Epibrassinolide(BR) for 3 d. Two hundred sampling pods from different plants were randomly collected to measure seed related indexes with a 4 d interval from 7 to 47 d after peak anthesis (DAPA).Seed color turned light brown at 31 or 35 DAPA after BR treatment, seed dry weight (DWT)was increased while seed moisture content (SMC) was decreased during seed development.DWT almost reached the maximum value when SMC was 33.20% at 31 DAPA in 2010-2011 and 35.29% at 35 DAPA in 2011-2012 growing season after BR treatment. Similarly,the maximum values of standard germination test (SGT), accelerated aging test (AAT)and cold test (CT) were observed at 31 or 35 DAPA after BR treatment respectively. The high yield and seed oil content appeared at 31 or 35 DAPA accompanied with rapid decrease in total non-structural carbohydrate (TNC) in stems and leaves. Our study indicated that BR application advanced maturity of winter rapeseed by 4 to 8 days.展开更多
Rice(Oryza sativa)is a vital staple crop worldwide,providing food supply for billions of people.Therefore,increasing rice productivity is essential to meet the growing demand for food(Sasaki and Burr,2000).The panicle...Rice(Oryza sativa)is a vital staple crop worldwide,providing food supply for billions of people.Therefore,increasing rice productivity is essential to meet the growing demand for food(Sasaki and Burr,2000).The panicle is a branched inflorescence,it bears rice spikelets which develop into grains,playing a crucial role in determining the final grain yield.展开更多
The trade-off between yield and environmental effects caused by nitrogen fertilizer application is an important issue in wheat production.A reduction in fertile florets is one of the main reasons for the lower yields ...The trade-off between yield and environmental effects caused by nitrogen fertilizer application is an important issue in wheat production.A reduction in fertile florets is one of the main reasons for the lower yields under low nitrogen application rates.Brassinosteroids(BRs)have been found to play a role in nitrogen-induced rice spikelet degeneration.However,whether BRs play a role in wheat floret development and the mechanisms involved are not clear.Therefore,a nitrogen gradient experiment and exogenous spraying experiment were conducted to investigate the role and mechanism of BRs in wheat floret development under low nitrogen stress.The results showed that as the nitrogen application decreased,the endogenous BRs content of the spikes decreased,photosynthesis weakened,and total carbon,soluble sugar and starch in the spikes decreased,leading to a reduction in the number of fertile florets.Under low nitrogen stress,exogenous spraying of 24-epibrassinolide promoted photosynthesis,and stimulated stem fructan hydrolysis and the utilization and storage of sucrose in spikes,which directed more carbohydrates to the spikes and increased the number of fertile florets.In conclusion,BRs mediate the effects of nitrogen fertilizer on wheat floret development,and under low nitrogen stress,foliar spraying of 24-epibrassinolide promotes the flow of carbohydrates from the stem to the spikes,alleviating wheat floret degeneration.展开更多
Reducing nitrogen application rates can mitigate issues such as environmental degradation and resource wastage.However,it can also exacerbate problems such as wheat floret degeneration,leading to reduced yields.Theref...Reducing nitrogen application rates can mitigate issues such as environmental degradation and resource wastage.However,it can also exacerbate problems such as wheat floret degeneration,leading to reduced yields.Therefore,investigating wheat floret degeneration mechanisms under low-nitrogen stress and identifying mitigation measures are conducive to achieving high yields and sustainable development.To investigate the physiological mechanism of how low-nitrogen stress affects wheat floret degradation and whether exogenous brassinosteroids(BRs)can alleviate this stress,experiments were designed with treatments of three nitrogen application rates(N0,no nitrogen application;N1,120 kg ha–1 pure nitrogen;N2,240 kg ha–1 pure nitrogen)and exogenous spraying(N0CK,no nitrogen with water spraying;N0BR,no nitrogen with 24-epibrassinolide(an active brassinosteroid)spraying;N1,120 kg ha–1 pure nitrogen with water spraying).The results indicated that low-nitrogen stress generated a large amount of reactive oxygen species.Although wheat spikes synthesized flavonoids to combat oxidative stress,their energy metabolism(glycolysis and tricarboxylic acid cycle)and ascorbate-glutathione cycle were inhibited,which kept the reactive oxygen levels elevated within the spike,induced cell death and exacerbated floret degeneration.Furthermore,brassinosteroids played a role in regulating wheat floret degeneration under low-nitrogen stress.Exogenous foliar spraying of 24-epibrassinolide promoted energy metabolism and the ascorbate-glutathione cycle within the spike,which enhanced the energy charge and effectively mitigated a portion of the reactive oxygen induced by low-nitrogen stress,thereby alleviating the floret degeneration caused by low-nitrogen stress.In summary,low-nitrogen stress disrupts the redox homeostasis of wheat spikes,leading to floret degeneration,while brassinosteroids alleviate floret degeneration by improving the redox state of wheat spikes.This study provides theoretical support for balancing the contradiction between high yields and sustainable development and will be beneficial for the application of low nitrogen in production.展开更多
Sphingolipids are not only a pivotal component of membranes but also act as bioactive molecules.Cotton fiber is one of the longest plant cells and sphingolipids are closely associated with the development of cotton fi...Sphingolipids are not only a pivotal component of membranes but also act as bioactive molecules.Cotton fiber is one of the longest plant cells and sphingolipids are closely associated with the development of cotton fiber cells.However,their function in cotton fiber cell development and its action mechanism is unclear.Through cotton genetic transformation and chemistry biological approach,we identified the function and action mechanism of the glucosylceramide synthase gene GhGCS1 and its product glucosylceramide(GluCer)in cotton fiber growth.GhGCS1 was preferentially expressed at the stage of fiber elongation and localized in the endoplasmic reticulum.Overexpression of GhGCS1 promoted GluCer synthesis and fiber elongation,which was consistent with the exogenous application of GluCer(FA-C22)(containing very long-acyl-chain fatty acid)to cotton fiber in ovule culture system in vitro.Contrarily,suppressing GhGCS1 expression inhibited GluCer synthesis and fiber elongation,which was similar as the exogenous application of GluCer synthesis inhibitor,PDMP.Transcriptome analysis revealed that the fiber elongation regulated by GhGCS1 was associated with brassinosteroid(BR)synthesis and signaling related gene expression.Meanwhile,we detected the BL content of control and transgenic fiber cells.The BL content significantly increased and decreased in up-and down-regulated transgenic fibers when compared with control fibers,respectively.Furthermore,we found that PDMP treatment blocked BR synthesis and signal transduction,while exogenous application of GluCer could enhance BR synthesis and signaling.Overall,our results revealed that GhGCS1 and GluCer regulated cotton fiber elongation by influencing BR synthesis and signaling.Our study shed a novel insight on regulatory mechanism of cotton fiber elongation and provides theoretical support,genetic resources and novel transgenic materials for improvement of crop quality.展开更多
Rice tillering,a key architecture trait determ ining grain yield,is highly regulated by a class of newly identified phytohorm ones,strigolactones(SLs).How ever,the whole SL signaling pathw ay from the receptor to dow ...Rice tillering,a key architecture trait determ ining grain yield,is highly regulated by a class of newly identified phytohorm ones,strigolactones(SLs).How ever,the whole SL signaling pathw ay from the receptor to dow nstream transcription factors to finally inhibit tillering remains unrevealed.In this study,we first found that brassinosteroids(BRs)strongly enhance tillering by prom oting bud outgrow th in rice,which is largely different from the function of BRs in Arabidopsis.Genetic and biochem ical analyses indicated that both the SL and BR signaling pathw ays control rice tillering by regulating the stability of D53 and/or the OsBZR1 RLA1-DLT module,a transcriptional complex in the rice BR signaling pathway.We further found that D53 interacts with OsBZR1 to inhibit the expression of FC1,a local inhibitor of tillering,and that this inhibition depends on direct DNA binding by OsBZR1,which recruits D53 to the FC1 promoter in rice buds.Taken together,these findings uncover a mechanism illustrating how SLs and BRs coordinately regulate rice tillering via the early responsive gene FC1.展开更多
Brassinosteroids （BRs） are natural plant hormones critical for growth and development. BR-deficient or signaling mutants show significantly shortened root phenotypes. But for a long time, it was thought that these p...Brassinosteroids （BRs） are natural plant hormones critical for growth and development. BR-deficient or signaling mutants show significantly shortened root phenotypes. But for a long time, it was thought that these phenotypes were solely caused by reduced root cell elongation in the mutants. Functions of BRs in regulating root development have been largely neglected. Recent detailed analyses, however, revealed that BRs are not only involved in root cell elongation but are also involved in many aspects of root development, such as maintenance of meristem size, root hair formation, lateral root initiation, gravitropic response, mycorrhiza formation, and nodulation in legume species. In this review, current findings on the functions of BRs in mediating root growth, development, and symbiosis are discussed.展开更多
Brassinosteroids （BRs） are an important class of phytohormones which regulates a wide range of physiological processes. Genetic and physiological studies have revealed that BR responses usually depend on an intact a...Brassinosteroids （BRs） are an important class of phytohormones which regulates a wide range of physiological processes. Genetic and physiological studies have revealed that BR responses usually depend on an intact auxin signaling pathway. Here, we demonstrate that high BR concentration or enhanced BR signaling induce the differential growth of etiolated hypocotyls and result in the morphological changes, while auxin-resistant mutants, msg2 （dominant mutant of IAA19） and arf7, are insensitive to the BR effect and can partially suppress the phenotype of bzrl-D （dominant mutant of BZR1 with enhanced BR signaling）. Interestingly, BZR1 protein can directly bind to the promoter regions of both IAA19 and ARFT, indicating that IAA19 and ARF7 mediate the BR-induced differential growth by serving as direct targets of BZR1. Systemic microarray analysis revealed that a number of BR-responsive genes showed reduced BR response in msg2, confirming that BR employs auxin signaling components IAA19 and ARF7 to modulate the specific downstream processes. These results provide informative clues on the crosstalk of BR-auxin signaling and the mechanisms of BR-auxin effects in regulating differential growth.展开更多
For adaptation to ever-changing environments,plants have evolved elaborate metabolic systems coupled to a regulatory network for optimal growth and defense. Regulation of plant secondary metabolic pathways such as glu...For adaptation to ever-changing environments,plants have evolved elaborate metabolic systems coupled to a regulatory network for optimal growth and defense. Regulation of plant secondary metabolic pathways such as glucosinolates(GSLs) by defense phytohormones in response to different stresses and nutrient deficiency has been intensively investigated, while how growth-promoting hormone balances plant secondary and primary metabolism has been largely unexplored. Here, we found that growth-promoting hormone brassinosteroid(BR) inhibits GSLs accumulation while enhancing biosynthesis of primary sulfur metabolites, including cysteine(Cys) and glutathione(GSH) both in Arabidopsis and Brassica crops, fine-tuning secondary and primary sulfur metabolism to promote plant growth. Furthermore, we demonstrate that of BRASSINAZOLE RESISTANT 1(BZR1), the central component of BR signaling, exerts distinct transcriptional inhibition regulation on indolic and aliphatic GSL via direct MYB51 dependent repression of indolic GSL biosynthesis, while exerting partial MYB29 dependent repression of aliphatic GSL biosynthesis. Additionally, BZR1 directly activates the transcription of APR1 and APR2 which encodes rate-limiting enzyme adenosine 5′-phosphosulfate reductases in the primary sulfur metabolic pathway.In summary, our findings indicate that BR inhibits the biosynthesis of GSLs to prioritize sulfur usage for primary metabolites under normal growth conditions.These findings expand our understanding of BR promoting plant growth from a metabolism perspective.展开更多
In Arabidopsis,stomatal development initiates after protodermal cells acquire stomatal lineage cell fate.Stomata or their precursors communicate with their neighbor epidermal cells to ensure the ＂one cell spacing＂ r...In Arabidopsis,stomatal development initiates after protodermal cells acquire stomatal lineage cell fate.Stomata or their precursors communicate with their neighbor epidermal cells to ensure the ＂one cell spacing＂ rule.The signals from EPF/EPFL peptide ligands received by TOO MANY MOUTHS（TMM）and ERECTA-family receptors are supposed to be transduced by YODA MAPK cascade.A basic helix-loop-helix transcription factor SPEECHLESS（SPCH） is another key regulator of stomatal cell fate determination and asymmetric entry divisions,and SPCH activity is regulated by YODA MAPK cascade.Brassinosteroid（BR） signaling,one of the most well characterized signal transduction pathways in plants,contributes to the control of stomatal production.But opposite organ-specific effects of BR on stomatal production were reported.Here we confirm thatstomatal production in hypocotyls is controlled by BR levels.YODA and CYCD4 are not essential for BR stomata-promoting function.Furthermore,we found that BR could confer tmm hypocotyls clustered stomatal phenotype,indicating that the BR organ-specific effects on stomatal production might coordinate with the TMM organ-specific actions.展开更多
Translational repression is a conserved mechanism in microRNA(miRNA)-guided gene silencing.In Arabidopsis,ARGONAUTE1(AGO1),the major miRNA effector,localizes in the cytoplasm for mRNA cleavage and at the endoplasmic r...Translational repression is a conserved mechanism in microRNA(miRNA)-guided gene silencing.In Arabidopsis,ARGONAUTE1(AGO1),the major miRNA effector,localizes in the cytoplasm for mRNA cleavage and at the endoplasmic reticulum(ER)for translational repression of target genes.However,the mechanism underlying miRNA-mediated translational repression is poorly understood.In particular,how the subcellular partitioning of AGO1 is regulated is largely unexplored.Here,we show that the plant hormone brassinosteroids(BRs)inhibit miRNA-mediated translational repression by negatively regulating the distribution of AGO1 at the ER in Arabidopsis thaliana.We show that the protein levels rather than the transcript levels of miRNA target genes were reduced in BR-deficient mutants but increased under BR treatments.The localization of AGO1 at the ER was significantly decreased under BR treatments while it was increased in the BR-deficient mutants.Moreover,ROTUNDIFOLIA3(ROT3),an enzyme involved in BR biosynthesis,co-localizes with AGO1 at the ER and interacts with AGO1 in a GW motif-dependent manner.Complementation analysis showed that the AGO1-ROT3 interaction is necessary for the function of ROT3.Our findings provide new clues to understand how miRNA-mediated gene silencing is regulated by plant endogenous hormones.展开更多
High temperature adversely affects plant growth and development.The steroid phytohormones brassinosteroids(BRs)are recognized to play important roles in plant heat stress responses and thermotolerance,but the underlyi...High temperature adversely affects plant growth and development.The steroid phytohormones brassinosteroids(BRs)are recognized to play important roles in plant heat stress responses and thermotolerance,but the underlying mechanisms remain obscure.Here,we demonstrate that the glycogen synthase kinase 3(GSK3)-like kinase BRASSINOSTEROID INSENSITIVE2(BIN2),a negative component in the BR signaling pathway,interacts with the master heat-responsive transcription factors CLASS A1 HEAT SHOCK TRANSCRIPTION FACTORS(HsfA1s).Furthermore,BIN2 phosphorylates HsfA1d on T263 and S56 to suppress its nuclear localization and inhibit its DNA-binding ability,respectively.BR signaling promotes plant thermotolerance by releasing the BIN2 suppression of HsfA1d to facilitate its nuclear localization and DNA binding.Our study provides insights into the molecular mechanisms by which BRs promote plant thermotolerance by strongly regulating HsfA1d through BIN2 and suggests potential ways to improve crop yield under extreme high temperatures.展开更多
Brassinolide (BR) is a new potent growth promoting steroid substance which was first isolated from rape pollen by Grove et al. in 1979. Since then a number of BR analogues, such as homobrassinolide 2 and epibrassinoli...Brassinolide (BR) is a new potent growth promoting steroid substance which was first isolated from rape pollen by Grove et al. in 1979. Since then a number of BR analogues, such as homobrassinolide 2 and epibrassinolide 3, have been discovered in plant. Unnatural compounds with similar structure to brassinolide have展开更多
The role of brassinosteroids(BRs)in enabling plants to respond effectively to adverse conditions is well known,though the precise mechanism of action that helps plants cope with arsenic(As)toxicity is still difficult ...The role of brassinosteroids(BRs)in enabling plants to respond effectively to adverse conditions is well known,though the precise mechanism of action that helps plants cope with arsenic(As)toxicity is still difficult to interpret.Therefore we tested the effect of brassinolide(BL)spray(0,0.5,and 1 mg·L^(-1))on As(0,and 10 mg·L^(-1))stressed tomato defense responses As stress led to the induction of oxidative stress,impaired chlorophyll and nitrogen metabolism,and Fe uptake,in conjunction with a reduction in plant growth and biomass.BL spray,on the contrary,protected the photo synthetic system and helped plants grow better under As stress.This was achieved by controlling the metabolism of chlorophyll and proline and lowering the amounts of methylglyoxal and H_(2)O_(2) through glyoxalaseⅠandⅡand antioxidant enzyme s.BL decreased arsenic accumulation by directing As sequestration towards vacuoles and increased Fe amount in the leaves and roots by regulating the expression of As(Lsil and Lsi2)and Fe(IRT1,IRT2,NRAMP1,and NRAMP3)transporters in As-stressed tomatoes.Furthermore,BL boosted adaptability against As phytotoxicity,while reducing the damaging impacts on photosynthesis,nitrogen metabolism,sulfur asimilation,and Fe absorption.These results offer a solid framework for the development of exogenous BRs-based breeding strategies for safer agricultural development.展开更多
Brassinosteroids play diverse roles in plant growth and development. Plants deficient in brassinosteroid （BR） biosynthesis or defective in signal transduction show many abnormal developmental phenotypes, indicating ...Brassinosteroids play diverse roles in plant growth and development. Plants deficient in brassinosteroid （BR） biosynthesis or defective in signal transduction show many abnormal developmental phenotypes, indicating the importance of both BR biosynthesis and the signaling pathway in regulating these biological processes. Recently, using genetics, proteomics, genomics, cell biology, and many other approaches, more components involved in the BR signaling pathway were identified. Furthermore, the physiological, cellular, and molecular mechanisms by which BRs regulate various aspects of plant development, are being discovered. These include root development, anther and pollen development and formation, stem elongation, vasculature differentiation, and cellulose biosynthesis, suggesting that the biological functions of BRs are far beyond promoting cell elongation, This review will focus on the up-to-date progresses about regulatory mechanisms of the BR signaling pathway and the physiological and molecular mechanisms whereby BRs regulate plant growth and development.展开更多
基金supported by STI 2030–Major Projects (2023ZD0407101)National Key Research and Development Program of China (2022YFD1201700)+1 种基金National Natural Science Foundation (U21A20208,32201704)Innovation Program of CAAS。
文摘The rapid elongation of rice(Oryza sativa)coleoptile is pivotal for the plant plumule to evade hypoxia stress induced by submergence,a condition often arising from overirrigation,ponding,rainstorms,or flooding.While brassinosteroids(BRs)are recognized for their diverse roles in plant growth and development,their influence on coleoptile elongation under hypoxic conditions remains largely unexplored.In this study,we demonstrate the significant requirement of BRs for coleoptile elongation in deep water.During coleoptile development,Glycogen Synthase Kinase3-Like Kinase2(GSK2),the central inhibitor of BR signaling in rice,undergoes substantial suppression in deep water but induction in air.In contrast,the dephosphorylated form of BRASSINAZOLE RESISTANT1(OsBZR1),representing the active form of the key BR signaling transcription factor,is induced in water but suppressed in air.Remarkably,the knockout of GSK3-like kinase genes significantly enhances coleoptile elongation in deep water,strongly indicating a vital contribution of BR response to hypoxia-stimulated coleoptile elongation.Transcriptome analysis uncovers both BR-associated and BR-independent hypoxia responses,implicating substance metabolism,redox reactions,abiotic stress responses,and crosstalk with other hormones in the regulation of BR-induced hypoxia responses.In summary,our findings suggest that rice plumules rapidly elongate coleoptiles through the activation of BR response in deep water,enabling them to escape from submergence-induced hypoxia stress.
基金supported by the National Natural Science Foundation of China(31771710,31901445)the National Key Research and Development Program of China(2016YFD03002064,2018YFD0300800)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Top Talent Supporting Program of Yangzhou University(2015-01)。
文摘Brassinosteroids(BRs)play critical roles in a wide range of plant developmental processes.However,it is unknown whether and how BRs mediate the effect of high temperature(HT)stress during anthesis on the pistil activity of photo-thermosensitive genetic male-sterile(PTSGMS)rice(Oryza sativa L.)lines.This study investigated the question.Three pot-grown PTSGMS rice lines were subjected to HT stress during anthesis.The contents of 24-epibrassinolide(24-EBL)and 28-homobrassinolide(28-HBL),the major forms of BR in rice plants,and levels of reactive oxygen species(ROS)or antioxidants(AOS),hydrogen peroxide(H2O2),1-aminocylopropane-1-carboxylic acid(ACC),ascorbic acid(AsA),and catalase activity in pistils,were determined.HT stress significantly reduced the contents of both 24-EBL and 28-EBL relative to those under normal temperatures,but the reduction varied by PTSGMS line.A line with higher BR contents under HT stress showed lower contents of ACC and H2O2,higher catalase activity and AsA content in pistils,and higher fertilization rate,seed-setting rate,and seed yield when the line was crossed with a restorer line,indicating that higher levels of BRs increase HT stress resistance.Applying 24-EBL,28-HBL or an inhibitor of BR biosynthesis confirmed the roles of BRs in response to HT stress.The results suggest that BRs mediate the effect of HT stress on pistil activity during anthesis and alleviate the harm of HT stress by increasing AOS and suppressing ROS generation.
基金supported by the National Natural Science Foundation of China(31771710,32071943)the National Key Research and Development Program of China(2018YFD0300800)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD-1)。
文摘High temperature (HT) stress has become one of the most detrimental stresses in crop production among constantly changing environmental factors.Exploiting approaches to enhance crop thermotolerance would have great significance in assuaging adverse effects of HT stress on crop growth and development.As jasmonates (JAs) and brassinosteroids (BRs) are novel phytohormones and play important roles in responses to biotic and abiotic stresses and in a wide range of plant developmental processes,this paper reviewed the roles and mechanisms of JAs and BRs in mitigating HT stress,with focus on rice (Oryza sativa L.) subjected to HT stress during anthesis.It is demonstrated that JAs alleviate spikelet-opening impairment and BRs ameliorate pistil fertilization ability under HT stress during anthesis of rice,although there are controversial observations.Activating the defense system,enhancing osmotic regulation,protecting photosynthesis,and interacting with other phytohormones,especially with ethylene and abscisic acid,are main physiological mechanisms by which JAs or BRs attenuate HT stress to plants.Elevating levels of JAs or BRs in plants could be considered as an important approach to enhance crop thermotolerance through breeding new varieties.Using JAs or BRs as chemical regulators and adopting proper water and nitrogen management practices could reduce the harm of HT stress to rice.Further research is needed to elucidate the roles of JAs and BRs in different plant tissues in responses to HT stress under different genetic backgrounds and environments,reveal the molecular mechanism underlying JAs and BRs mediating HT stress,understand the cross-talk between phytohormones in modulating HT stress,and establish integrated crop management to minimize the hazard of HT stress in rice production.
基金supported by National Key Research and Development Program of China(2017YFD0300410)。
文摘Brassinosteroids(BRs)are steroid hormones that function in plant growth and development and response to environmental stresses and nutrient supplies.However,few studies have investigated the effect of BRs in modulating the physiological response to nitrogen(N)supply in maize.In the present study,BR signalingdeficient mutant zmbri1-RNAi lines and exogenous application of 2,4-epibrassinolide(e BL)were used to study the role of BRs in the regulation of physiological response in maize seedlings supplied with N.Exogenous application of e BL increased primary root length and plant biomass,but zmbri1 plants showed shorter primary roots and less plant biomass than wild-type plants under low N(LN)and normal N(NN)conditions.LN induced the expression of the BR signaling-associated genes Zm DWF4,Zm CPD,Zm DET2,and Zm BZR1 and the production of longer primary roots than NN.Knockdown of Zm BRI1 weakened the biological effects of LN-induced primary root elongation.e BL treatment increased N accumulation in shoots and roots of maize seedlings exposed to LN or NN treatment.Correspondingly,zmbri1 plants showed lower N accumulation in shoots and roots than wild-type plants.Along with reduced N accumulation,zmbri1 plants showed lower NO3-fluxes and^(15)NO_(3)^(-)uptake.The expression of nitrate transporter(NRT)genes(Zm NPF6.4,Zm NPF6.6,Zm NRT2.1,Zm NRT2.2)was lower in zmbri1 than in wild-type roots,but e BL treatments up-regulated the transcript expression of NRT genes.Thus,BRs modulated N physiological response and regulated the transcript expression of NRT genes to promote N uptake in maize.
文摘Soil contamination with heavy metals has become a world-wide problem, leading to the loss in agricultural productivity. Plants have a remarkable ability to take up and accumulate heavy metals from their external environment and it is well known that high levels of heavy metals affect different physiological and metabolic processes. Brassinosteroids are considered as the sixth class of plant hormones and they are essential for plant growth and development. These compounds are able of inducing abiotic stress tolerance in plants. In this paper, information about brassinosteroids and plant responses to heavy metal stress is reviewed.
文摘Long developmental stage and late harvest time of winter rapeseed (Brassica napus L.) have great negative effects on rice planting of rice-rapeseed farming system in China. Early maturity improvement of rapeseed is necessary. ‘Zhongshuang 11’, an elite winter rapeseed cultivar, was used in consecutive field experiments during 2010-2012. At initial flowering stage, plants were consecutively sprayed with 0.1 mg/L 2-4-Epibrassinolide(BR) for 3 d. Two hundred sampling pods from different plants were randomly collected to measure seed related indexes with a 4 d interval from 7 to 47 d after peak anthesis (DAPA).Seed color turned light brown at 31 or 35 DAPA after BR treatment, seed dry weight (DWT)was increased while seed moisture content (SMC) was decreased during seed development.DWT almost reached the maximum value when SMC was 33.20% at 31 DAPA in 2010-2011 and 35.29% at 35 DAPA in 2011-2012 growing season after BR treatment. Similarly,the maximum values of standard germination test (SGT), accelerated aging test (AAT)and cold test (CT) were observed at 31 or 35 DAPA after BR treatment respectively. The high yield and seed oil content appeared at 31 or 35 DAPA accompanied with rapid decrease in total non-structural carbohydrate (TNC) in stems and leaves. Our study indicated that BR application advanced maturity of winter rapeseed by 4 to 8 days.
基金supported by the Taishan Scholars Program(tsqn202306306)the Key Research and Development Program of Shandong Province(2022LZGC005)the National Natural Science Foundation of China(U24A20389)。
文摘Rice(Oryza sativa)is a vital staple crop worldwide,providing food supply for billions of people.Therefore,increasing rice productivity is essential to meet the growing demand for food(Sasaki and Burr,2000).The panicle is a branched inflorescence,it bears rice spikelets which develop into grains,playing a crucial role in determining the final grain yield.
基金supported by the Key Research and Development Program of Shaanxi,China(2021NY-083)the National Natural Science Foundation of China(31871567)。
文摘The trade-off between yield and environmental effects caused by nitrogen fertilizer application is an important issue in wheat production.A reduction in fertile florets is one of the main reasons for the lower yields under low nitrogen application rates.Brassinosteroids(BRs)have been found to play a role in nitrogen-induced rice spikelet degeneration.However,whether BRs play a role in wheat floret development and the mechanisms involved are not clear.Therefore,a nitrogen gradient experiment and exogenous spraying experiment were conducted to investigate the role and mechanism of BRs in wheat floret development under low nitrogen stress.The results showed that as the nitrogen application decreased,the endogenous BRs content of the spikes decreased,photosynthesis weakened,and total carbon,soluble sugar and starch in the spikes decreased,leading to a reduction in the number of fertile florets.Under low nitrogen stress,exogenous spraying of 24-epibrassinolide promoted photosynthesis,and stimulated stem fructan hydrolysis and the utilization and storage of sucrose in spikes,which directed more carbohydrates to the spikes and increased the number of fertile florets.In conclusion,BRs mediate the effects of nitrogen fertilizer on wheat floret development,and under low nitrogen stress,foliar spraying of 24-epibrassinolide promotes the flow of carbohydrates from the stem to the spikes,alleviating wheat floret degeneration.
基金supported by the Key Research and Development Program of Shaanxi,China(2021NY-083)the National Natural Science Foundation of China(31871567)。
文摘Reducing nitrogen application rates can mitigate issues such as environmental degradation and resource wastage.However,it can also exacerbate problems such as wheat floret degeneration,leading to reduced yields.Therefore,investigating wheat floret degeneration mechanisms under low-nitrogen stress and identifying mitigation measures are conducive to achieving high yields and sustainable development.To investigate the physiological mechanism of how low-nitrogen stress affects wheat floret degradation and whether exogenous brassinosteroids(BRs)can alleviate this stress,experiments were designed with treatments of three nitrogen application rates(N0,no nitrogen application;N1,120 kg ha–1 pure nitrogen;N2,240 kg ha–1 pure nitrogen)and exogenous spraying(N0CK,no nitrogen with water spraying;N0BR,no nitrogen with 24-epibrassinolide(an active brassinosteroid)spraying;N1,120 kg ha–1 pure nitrogen with water spraying).The results indicated that low-nitrogen stress generated a large amount of reactive oxygen species.Although wheat spikes synthesized flavonoids to combat oxidative stress,their energy metabolism(glycolysis and tricarboxylic acid cycle)and ascorbate-glutathione cycle were inhibited,which kept the reactive oxygen levels elevated within the spike,induced cell death and exacerbated floret degeneration.Furthermore,brassinosteroids played a role in regulating wheat floret degeneration under low-nitrogen stress.Exogenous foliar spraying of 24-epibrassinolide promoted energy metabolism and the ascorbate-glutathione cycle within the spike,which enhanced the energy charge and effectively mitigated a portion of the reactive oxygen induced by low-nitrogen stress,thereby alleviating the floret degeneration caused by low-nitrogen stress.In summary,low-nitrogen stress disrupts the redox homeostasis of wheat spikes,leading to floret degeneration,while brassinosteroids alleviate floret degeneration by improving the redox state of wheat spikes.This study provides theoretical support for balancing the contradiction between high yields and sustainable development and will be beneficial for the application of low nitrogen in production.
基金funded by the National Natural Science Foundation of China(32372114,31971984)the Special Fund for Youth Team of the Southwest Universities(SWU-XJPY202306)+1 种基金the Chongqing Graduate Scientific Research Innovation Project(CYS23239)the Genetically Modified Organisms Breeding Major Project of China(2018ZX0800921B)。
文摘Sphingolipids are not only a pivotal component of membranes but also act as bioactive molecules.Cotton fiber is one of the longest plant cells and sphingolipids are closely associated with the development of cotton fiber cells.However,their function in cotton fiber cell development and its action mechanism is unclear.Through cotton genetic transformation and chemistry biological approach,we identified the function and action mechanism of the glucosylceramide synthase gene GhGCS1 and its product glucosylceramide(GluCer)in cotton fiber growth.GhGCS1 was preferentially expressed at the stage of fiber elongation and localized in the endoplasmic reticulum.Overexpression of GhGCS1 promoted GluCer synthesis and fiber elongation,which was consistent with the exogenous application of GluCer(FA-C22)(containing very long-acyl-chain fatty acid)to cotton fiber in ovule culture system in vitro.Contrarily,suppressing GhGCS1 expression inhibited GluCer synthesis and fiber elongation,which was similar as the exogenous application of GluCer synthesis inhibitor,PDMP.Transcriptome analysis revealed that the fiber elongation regulated by GhGCS1 was associated with brassinosteroid(BR)synthesis and signaling related gene expression.Meanwhile,we detected the BL content of control and transgenic fiber cells.The BL content significantly increased and decreased in up-and down-regulated transgenic fibers when compared with control fibers,respectively.Furthermore,we found that PDMP treatment blocked BR synthesis and signal transduction,while exogenous application of GluCer could enhance BR synthesis and signaling.Overall,our results revealed that GhGCS1 and GluCer regulated cotton fiber elongation by influencing BR synthesis and signaling.Our study shed a novel insight on regulatory mechanism of cotton fiber elongation and provides theoretical support,genetic resources and novel transgenic materials for improvement of crop quality.
基金This work was supported by grants from NNSFC(31430046 to X.W.),NKRDP(2016YFD0100403 to S.S.,2016YFD0100700 to Z.F.),ICPNNSFC(31661143024 to X.W.),MAITP(0120150092 to X.W.)School Independent Scientific and Technological Innovation Foundation and Research Startup Foundation of Huazhong Agricultural University(2662015PY020,2014RC002 to X.W.).
文摘Rice tillering,a key architecture trait determ ining grain yield,is highly regulated by a class of newly identified phytohorm ones,strigolactones(SLs).How ever,the whole SL signaling pathw ay from the receptor to dow nstream transcription factors to finally inhibit tillering remains unrevealed.In this study,we first found that brassinosteroids(BRs)strongly enhance tillering by prom oting bud outgrow th in rice,which is largely different from the function of BRs in Arabidopsis.Genetic and biochem ical analyses indicated that both the SL and BR signaling pathw ays control rice tillering by regulating the stability of D53 and/or the OsBZR1 RLA1-DLT module,a transcriptional complex in the rice BR signaling pathway.We further found that D53 interacts with OsBZR1 to inhibit the expression of FC1,a local inhibitor of tillering,and that this inhibition depends on direct DNA binding by OsBZR1,which recruits D53 to the FC1 promoter in rice buds.Taken together,these findings uncover a mechanism illustrating how SLs and BRs coordinately regulate rice tillering via the early responsive gene FC1.
文摘Brassinosteroids （BRs） are natural plant hormones critical for growth and development. BR-deficient or signaling mutants show significantly shortened root phenotypes. But for a long time, it was thought that these phenotypes were solely caused by reduced root cell elongation in the mutants. Functions of BRs in regulating root development have been largely neglected. Recent detailed analyses, however, revealed that BRs are not only involved in root cell elongation but are also involved in many aspects of root development, such as maintenance of meristem size, root hair formation, lateral root initiation, gravitropic response, mycorrhiza formation, and nodulation in legume species. In this review, current findings on the functions of BRs in mediating root growth, development, and symbiosis are discussed.
基金This study was supported by the National Science Foundation of China （Grant Nos： 91117009 and 90717001）.Wethank Dr Kotaro T. Yamamoto （Hokkaido University） for the gifts of msg2-1 seeds, Dr Zhi-Yong Wang （Stanford University） for providing bzrl-D seeds and seeds of pBZRI：：mBZR1-CFP transgenic plants, Prof. Hong-Quan Yang （Shanghai Jiao Tong University） for axr2-1 seeds, and Dr Jian-Ming Li （University of Michigan） for det2-1 seeds. No conflict of interest declared.
文摘Brassinosteroids （BRs） are an important class of phytohormones which regulates a wide range of physiological processes. Genetic and physiological studies have revealed that BR responses usually depend on an intact auxin signaling pathway. Here, we demonstrate that high BR concentration or enhanced BR signaling induce the differential growth of etiolated hypocotyls and result in the morphological changes, while auxin-resistant mutants, msg2 （dominant mutant of IAA19） and arf7, are insensitive to the BR effect and can partially suppress the phenotype of bzrl-D （dominant mutant of BZR1 with enhanced BR signaling）. Interestingly, BZR1 protein can directly bind to the promoter regions of both IAA19 and ARFT, indicating that IAA19 and ARF7 mediate the BR-induced differential growth by serving as direct targets of BZR1. Systemic microarray analysis revealed that a number of BR-responsive genes showed reduced BR response in msg2, confirming that BR employs auxin signaling components IAA19 and ARF7 to modulate the specific downstream processes. These results provide informative clues on the crosstalk of BR-auxin signaling and the mechanisms of BR-auxin effects in regulating differential growth.
基金supported by the National Science Foundation of China (31830078, 32172593, and 32202466)Zhejiang Provincial Ten-thousand Program for Leading Talents of Science and Technology Innovation (2018R52026)。
文摘For adaptation to ever-changing environments,plants have evolved elaborate metabolic systems coupled to a regulatory network for optimal growth and defense. Regulation of plant secondary metabolic pathways such as glucosinolates(GSLs) by defense phytohormones in response to different stresses and nutrient deficiency has been intensively investigated, while how growth-promoting hormone balances plant secondary and primary metabolism has been largely unexplored. Here, we found that growth-promoting hormone brassinosteroid(BR) inhibits GSLs accumulation while enhancing biosynthesis of primary sulfur metabolites, including cysteine(Cys) and glutathione(GSH) both in Arabidopsis and Brassica crops, fine-tuning secondary and primary sulfur metabolism to promote plant growth. Furthermore, we demonstrate that of BRASSINAZOLE RESISTANT 1(BZR1), the central component of BR signaling, exerts distinct transcriptional inhibition regulation on indolic and aliphatic GSL via direct MYB51 dependent repression of indolic GSL biosynthesis, while exerting partial MYB29 dependent repression of aliphatic GSL biosynthesis. Additionally, BZR1 directly activates the transcription of APR1 and APR2 which encodes rate-limiting enzyme adenosine 5′-phosphosulfate reductases in the primary sulfur metabolic pathway.In summary, our findings indicate that BR inhibits the biosynthesis of GSLs to prioritize sulfur usage for primary metabolites under normal growth conditions.These findings expand our understanding of BR promoting plant growth from a metabolism perspective.
基金supported by grants from Hundred Talents Program and KSCX2-YW-N-073 from the Chinese Academy of SciencesNational Natural Science Foundation of China (30971652,31271463,and 30171198)
文摘In Arabidopsis,stomatal development initiates after protodermal cells acquire stomatal lineage cell fate.Stomata or their precursors communicate with their neighbor epidermal cells to ensure the ＂one cell spacing＂ rule.The signals from EPF/EPFL peptide ligands received by TOO MANY MOUTHS（TMM）and ERECTA-family receptors are supposed to be transduced by YODA MAPK cascade.A basic helix-loop-helix transcription factor SPEECHLESS（SPCH） is another key regulator of stomatal cell fate determination and asymmetric entry divisions,and SPCH activity is regulated by YODA MAPK cascade.Brassinosteroid（BR） signaling,one of the most well characterized signal transduction pathways in plants,contributes to the control of stomatal production.But opposite organ-specific effects of BR on stomatal production were reported.Here we confirm thatstomatal production in hypocotyls is controlled by BR levels.YODA and CYCD4 are not essential for BR stomata-promoting function.Furthermore,we found that BR could confer tmm hypocotyls clustered stomatal phenotype,indicating that the BR organ-specific effects on stomatal production might coordinate with the TMM organ-specific actions.
基金We are grateful to Professors Yijun Qi for providing the AGO1p::GFP-AGO1 seeds,Xuelu Wang for providing the 35S::BKI1-YFP seeds,Jianxiang Liu for providing the 35S::ER-mCherry plasmid,Hong Ma for providing theTOE1-Myc and mTOE1-Myc seeds,Xuemei Chen for providing the 35S::YFP-AGO1 plasmid,Shengben Li for providing the CSD2-HA and mCSD2-HA seeds,Fang Chang for providing the bri1-5 seeds,and Jinzhong Lin for providing ultracentrifuge equipment and technical guidance.This work was supported by grants of the National Natural Science Foundation of China(32025005,31830045,M-0398).
文摘Translational repression is a conserved mechanism in microRNA(miRNA)-guided gene silencing.In Arabidopsis,ARGONAUTE1(AGO1),the major miRNA effector,localizes in the cytoplasm for mRNA cleavage and at the endoplasmic reticulum(ER)for translational repression of target genes.However,the mechanism underlying miRNA-mediated translational repression is poorly understood.In particular,how the subcellular partitioning of AGO1 is regulated is largely unexplored.Here,we show that the plant hormone brassinosteroids(BRs)inhibit miRNA-mediated translational repression by negatively regulating the distribution of AGO1 at the ER in Arabidopsis thaliana.We show that the protein levels rather than the transcript levels of miRNA target genes were reduced in BR-deficient mutants but increased under BR treatments.The localization of AGO1 at the ER was significantly decreased under BR treatments while it was increased in the BR-deficient mutants.Moreover,ROTUNDIFOLIA3(ROT3),an enzyme involved in BR biosynthesis,co-localizes with AGO1 at the ER and interacts with AGO1 in a GW motif-dependent manner.Complementation analysis showed that the AGO1-ROT3 interaction is necessary for the function of ROT3.Our findings provide new clues to understand how miRNA-mediated gene silencing is regulated by plant endogenous hormones.
基金supported by grant 31661143024 from the National Natural Science Foundation of China(to X.W.)grant 0120150092 from the Agricultural Research Outstanding Talents and Innovation Team of the Ministry of Agriculture(to X.W.).
文摘High temperature adversely affects plant growth and development.The steroid phytohormones brassinosteroids(BRs)are recognized to play important roles in plant heat stress responses and thermotolerance,but the underlying mechanisms remain obscure.Here,we demonstrate that the glycogen synthase kinase 3(GSK3)-like kinase BRASSINOSTEROID INSENSITIVE2(BIN2),a negative component in the BR signaling pathway,interacts with the master heat-responsive transcription factors CLASS A1 HEAT SHOCK TRANSCRIPTION FACTORS(HsfA1s).Furthermore,BIN2 phosphorylates HsfA1d on T263 and S56 to suppress its nuclear localization and inhibit its DNA-binding ability,respectively.BR signaling promotes plant thermotolerance by releasing the BIN2 suppression of HsfA1d to facilitate its nuclear localization and DNA binding.Our study provides insights into the molecular mechanisms by which BRs promote plant thermotolerance by strongly regulating HsfA1d through BIN2 and suggests potential ways to improve crop yield under extreme high temperatures.
文摘Brassinolide (BR) is a new potent growth promoting steroid substance which was first isolated from rape pollen by Grove et al. in 1979. Since then a number of BR analogues, such as homobrassinolide 2 and epibrassinolide 3, have been discovered in plant. Unnatural compounds with similar structure to brassinolide have
基金financial support from the National Key Research and Development Program of China(Grant No.2023YFD220120302)supported by RUDN University Strategic Academic Leadership Program。
文摘The role of brassinosteroids(BRs)in enabling plants to respond effectively to adverse conditions is well known,though the precise mechanism of action that helps plants cope with arsenic(As)toxicity is still difficult to interpret.Therefore we tested the effect of brassinolide(BL)spray(0,0.5,and 1 mg·L^(-1))on As(0,and 10 mg·L^(-1))stressed tomato defense responses As stress led to the induction of oxidative stress,impaired chlorophyll and nitrogen metabolism,and Fe uptake,in conjunction with a reduction in plant growth and biomass.BL spray,on the contrary,protected the photo synthetic system and helped plants grow better under As stress.This was achieved by controlling the metabolism of chlorophyll and proline and lowering the amounts of methylglyoxal and H_(2)O_(2) through glyoxalaseⅠandⅡand antioxidant enzyme s.BL decreased arsenic accumulation by directing As sequestration towards vacuoles and increased Fe amount in the leaves and roots by regulating the expression of As(Lsil and Lsi2)and Fe(IRT1,IRT2,NRAMP1,and NRAMP3)transporters in As-stressed tomatoes.Furthermore,BL boosted adaptability against As phytotoxicity,while reducing the damaging impacts on photosynthesis,nitrogen metabolism,sulfur asimilation,and Fe absorption.These results offer a solid framework for the development of exogenous BRs-based breeding strategies for safer agricultural development.
文摘Brassinosteroids play diverse roles in plant growth and development. Plants deficient in brassinosteroid （BR） biosynthesis or defective in signal transduction show many abnormal developmental phenotypes, indicating the importance of both BR biosynthesis and the signaling pathway in regulating these biological processes. Recently, using genetics, proteomics, genomics, cell biology, and many other approaches, more components involved in the BR signaling pathway were identified. Furthermore, the physiological, cellular, and molecular mechanisms by which BRs regulate various aspects of plant development, are being discovered. These include root development, anther and pollen development and formation, stem elongation, vasculature differentiation, and cellulose biosynthesis, suggesting that the biological functions of BRs are far beyond promoting cell elongation, This review will focus on the up-to-date progresses about regulatory mechanisms of the BR signaling pathway and the physiological and molecular mechanisms whereby BRs regulate plant growth and development.
