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
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
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
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
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
Lysine content is a criterion of the nutritional quality of rice.Understanding the process of lysine biosynthesis in early-flowering superior grain(SG)and late-flowering inferior grain(IG)of rice would advance breedin...Lysine content is a criterion of the nutritional quality of rice.Understanding the process of lysine biosynthesis in early-flowering superior grain(SG)and late-flowering inferior grain(IG)of rice would advance breeding and cultivation to improve nutritional quality.However,little information is available on differences in lysine anabolism between SG and IG and the underlying mechanism,and whether and how irrigation regimes affect lysine anabolism in these grains.A japonica rice cultivar was grown in the field and two irrigation regimes,continuous flooding(CF)and wetting alternating with partial drying(WAPD),were imposed from heading to the mature stage.Lysine content and activities of key enzymes of lysine biosynthesis,and levels of brassinosteroids(BRs)were lower in the IG than in the SG at the early grainfilling stage but higher at middle and late grain-filling stages.WAPD increased activities of these key enzymes,BR levels,and contents of lysine and total amino acids in IG,but not SG relative to CF.Application of 2,4-epibrassinolide to rice panicles in CF during early grain filling reproduced the effects of WAPD,but neither treatment altered the activities of enzymes responsible for lysine catabolism in either SG or IG.WAPD and elevated BR levels during grain filling increased lysine biosynthesis in IG.Improvement in lysine biosynthesis in rice should focus on IG.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
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
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
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
Salicylic acid (SA) plays an important role in plant immune response, including resistance to pathogens and systemic acquired resistance. Two major components, NONEXPRESSOR OF PATHOGENESIS-RELATED GENES (NPRs) and TGA...Salicylic acid (SA) plays an important role in plant immune response, including resistance to pathogens and systemic acquired resistance. Two major components, NONEXPRESSOR OF PATHOGENESIS-RELATED GENES (NPRs) and TGACG motif-binding transcription factors (TGAs), are known to mediate SA signaling, which might also be orchestrated by other hormonal and environmental changes. Nevertheless, the molecular and functional interactions between SA signaling components and other cellular signaling pathways remain poorly understood. Here we showed that the steroid plant hormone brassinosteroid (BR) promotes SA responses by inactivating BR-INSENSITIVE 2 (BIN2), which inhibits the redox-sensitive clade I TGAs in Arabidopsis. We found that both BR and the BIN2 inhibitor bikinin synergistically increase SA-mediated physiological responses, such as resistance to Pst DC3000. Our genetic and biochemical analyses indicated that BIN2 functionally interacts with TGA1 and TGA4, but not with other TGAs. We further demonstrated that BIN2 phosphorylates Ser-202 of TGA4, resulting in the suppression of the redox-dependent interaction between TGA4 and NPR1 as well as destabilization of TGA4. Consistently, transgenic Arabidopsis overexpressing TGA4-YFP with a S202A mutation displayed enhanced SA responses compared to the wild-type TGA4-YFP plants. Taken together, these results suggest a novel crosstalk mechanism by which BR signaling coordinates the SA responses mediated by redox-sensitive clade I TGAs.展开更多
IQ67-domain(IQD)proteins function in plant defense and in organ development.The mechanisms by which they influence cotton fiber development are unknown.In the present study,GhIQD10 was expressed mainly in the transiti...IQ67-domain(IQD)proteins function in plant defense and in organ development.The mechanisms by which they influence cotton fiber development are unknown.In the present study,GhIQD10 was expressed mainly in the transition period of cotton fiber development,and GhIQD10-overexpression lines showed shorter fibers.GhIQD10 interacted with GhCaM7 and the interaction was inhibited by Ca^(2+).In in vitro ovule culture,Ca^(2+)rescued the shorter-fiber phenotype of GhIQD10-overexpression lines,which were insensitive to the Ca^(2+)channel inhibitor verapamil and the Ca^(2+)pool release channel blocker 2-aminoethoxydiphenyl borate.We conclude that GhIQD10 affects cotton fiber elongation via Ca^(2+)signaling by interacting with GhCaM7.Brassinosteroid(BR)biosynthesis and signaling genes were up-regulated in GhIQD10-overexpression lines.Fiber development in these lines was not affected by epibrassinolide or the BR biosynthesis inhibitor brassinozole,indicating that the influence of GhIQD10 on fiber elongation was not associated with BR.展开更多
Brassinosteroids (BRs) and polyamines (PAs) are widely used to overcome abiotic stresses including salinity stress (NaCl) in plants. In the present investigation, we evaluated the co-application efficacy of 24-epibras...Brassinosteroids (BRs) and polyamines (PAs) are widely used to overcome abiotic stresses including salinity stress (NaCl) in plants. In the present investigation, we evaluated the co-application efficacy of 24-epibrassinolide (EBR, a highly active BR) and putrescine (Put, a PA) on the NaCl stress (75 mM and 150 mM) tolerance of Lycopersicon esculentum L. cv. kuber geeta plants. A small rise in protein content was recorded under salinity stress in comparison with untreated control. The NaCl stress was found to significantly enhance the activities of guaiacol peroxidase (GPOX) and superoxide dismutase (SOD);while decline in catalase (CAT) activity was recorded when compared with the untreated control. Salinity stress both at 75 mM and 150 mM was able to cause significant membrane damage as evidenced by an increase in the level of malondialdehyde (MDA) content over untreated control. The EBR and Put co-applications were able to improve protein content in NaCl stressed plants over only NaCl stressed plants. The co-applications of EBR and Put were able to significantly enhance the activities of CAT, SOD and GPOX in L. esculentum under salinity stress (75 mM and 150 mM) when compared with NaCl stressed plants alone. Major decline in the MDA level recorded for EBR and Put co-applications under NaCl stress revealed reduced membrane damages when compared with NaCl stressed plants alone. Our findings provide evidence that EBR and Put co-applications are effective in amelioration of NaCl stress in L. esculentum. Thus co-application potential of EBR and Put may acts an eco-friendly approach towards NaCl stress mitigation in economically important crops.展开更多
Brassinosteroids (BRs) are a large group of polyhydroxy steroids, which regulate numerous aspects of plant growth and development, including stem elongation, leaf bending, tracheary element differentiation, stress pro...Brassinosteroids (BRs) are a large group of polyhydroxy steroids, which regulate numerous aspects of plant growth and development, including stem elongation, leaf bending, tracheary element differentiation, stress protection and photomorphogenesis. Recent studies indicate antigenotoxic and anticancerous activities of these compounds. The role of natural BRs in H2O2 (hydrogen peroxide) -induced DNA damage in human lymphocytes is still unknown. The present study reports the presence of Castasterone from leaves of Centella asiatica, an important medicinal herb commonly used as a memory enhancer and immunomodulator. CA50 fraction isolated from Centella asiatica was characterized as Castasterone by electrospray ionization mass spectral data with standard Castasterone. An attempt has been made to study antigenotoxic activity of the isolated Castasterone against H2O2 -induced DNA damage in human blood lymphocytes using Single cell gel electrophoresis assay (Comet Assay). Castasterone at 10–9 M concentration proved to be effective in diminishing the DNA damage by 89.42 %.展开更多
ebisu dwarf (d2) is a mutant caused by mutation in a rice brassinosteroid biosynthetic enzyme gene, CYP90D2/D2, thereby conferring a brassinosteroid-deficient dwarf phenotype. Three newly isolated d2 alleles derived f...ebisu dwarf (d2) is a mutant caused by mutation in a rice brassinosteroid biosynthetic enzyme gene, CYP90D2/D2, thereby conferring a brassinosteroid-deficient dwarf phenotype. Three newly isolated d2 alleles derived from a Nippon- bare mutant library (d2-3, d2-4, and d2-6) produced more severe dwarf phenotypes than the previously characterized null allele from a Taichung 65 mutant library, d2-1. Linkage analysis and a complementation test clearly indicated that the mutant phenotypes in d2-6 were caused by defects in CYP90D2/D2, and exogenous treatment with brassinolide, a bioactive brassinosteroid, rescued the dwarf phenotype of three Nipponbare-derived d2 mutants. However, the content of endogenous bioactive brassinosteroid, castasterone, and the expression of brassinosteroid-response genes indicated that partial suppression of the brassinosteroid response in addition to a brassinosteroid deficiency has occurred in the Nipponbare-derived d2 mutants. Based on these results, we discuss the possibility that wild-type Nipponbare has some defects in an unknown factor or factors related to the brassinosteroid response in rice.展开更多
Leaf inclination,a component of crop architecture,influences photosynthetic efficiency and planting density.Various factors,particularly the phytohormones auxin and brassinosteroids(BRs),function in regulating lamina ...Leaf inclination,a component of crop architecture,influences photosynthetic efficiency and planting density.Various factors,particularly the phytohormones auxin and brassinosteroids(BRs),function in regulating lamina joint bending,and understanding of the genetic control of leaf inclination will help to elucidate the relevant regulatory network.Screening a rice T-DNA insertion population revealed a mutant that was insensitive to auxin and displayed an enlarged leaf angle due to increased cell length on the adaxial side of the lamina joint.Genetic analysis revealed that the increased leaf inclination was caused by T-DNA insertion in the promoter region of OsIAA6,resulting in elevated OsIAA6 expression.Further study showed that OsIAA6 interacts with OsARF1 to suppress auxin signaling and regulates leaf inclination.OsIAA6 mediates the BR effects on lamina joint development,and OsBZR1,the key transcription factor in BR signaling,binds directly to the promoter of OsIAA6 to stimulate its transcription.These results indicate the roles of the OsIAA6-OsARF1 module in regulating rice leaf inclination and suggest the synergistic effects of the phytohormones auxin and BR.展开更多
Two potential BRASSINAZOLE RESISTANT 1 (BZR1) homologs were downregulated by brassinosteroids(BRs) in Setaria italica roots.Functional analysis showed that BR regulates the dephosphorylation and nuclear localization o...Two potential BRASSINAZOLE RESISTANT 1 (BZR1) homologs were downregulated by brassinosteroids(BRs) in Setaria italica roots.Functional analysis showed that BR regulates the dephosphorylation and nuclear localization of Si BZR1 and that Si BZR1 binds conserved BZR1-recognizing cis elements.In comparison with the wild type,Si BZR1-overexpressing S.italica seedlings were more sensitive to BR-inhibited primary root growth and drought stress,indicating that Si BZR1 is a positive regulator of BR signaling and a negative regulator of drought tolerance in S.italica.PLETHORA-LIKE 1 (Si PLT-L1) was found to be a direct target gene of Si BZR1 in S.italica roots.The expression of Si PLT-L1 was downregulated by Si BZR1.Si PLT-L1-overexpressing S.italica was less sensitive to BR-inhibited root growth and more tolerant to drought stress,possibly owing to the upregulation of drought-inducible Dehydrin-family genes.展开更多
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 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.
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.
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 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This work was supported by the National Natural Science Foundation of China(32071943,32272198).
文摘Lysine content is a criterion of the nutritional quality of rice.Understanding the process of lysine biosynthesis in early-flowering superior grain(SG)and late-flowering inferior grain(IG)of rice would advance breeding and cultivation to improve nutritional quality.However,little information is available on differences in lysine anabolism between SG and IG and the underlying mechanism,and whether and how irrigation regimes affect lysine anabolism in these grains.A japonica rice cultivar was grown in the field and two irrigation regimes,continuous flooding(CF)and wetting alternating with partial drying(WAPD),were imposed from heading to the mature stage.Lysine content and activities of key enzymes of lysine biosynthesis,and levels of brassinosteroids(BRs)were lower in the IG than in the SG at the early grainfilling stage but higher at middle and late grain-filling stages.WAPD increased activities of these key enzymes,BR levels,and contents of lysine and total amino acids in IG,but not SG relative to CF.Application of 2,4-epibrassinolide to rice panicles in CF during early grain filling reproduced the effects of WAPD,but neither treatment altered the activities of enzymes responsible for lysine catabolism in either SG or IG.WAPD and elevated BR levels during grain filling increased lysine biosynthesis in IG.Improvement in lysine biosynthesis in rice should focus on IG.
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.
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.
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.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT,orMinistryof Education)(2021R1A2C1006617 and 2020R1A6A1A06046728 to T.W.K.2021R1A2C1007516toS-K.K).
文摘Salicylic acid (SA) plays an important role in plant immune response, including resistance to pathogens and systemic acquired resistance. Two major components, NONEXPRESSOR OF PATHOGENESIS-RELATED GENES (NPRs) and TGACG motif-binding transcription factors (TGAs), are known to mediate SA signaling, which might also be orchestrated by other hormonal and environmental changes. Nevertheless, the molecular and functional interactions between SA signaling components and other cellular signaling pathways remain poorly understood. Here we showed that the steroid plant hormone brassinosteroid (BR) promotes SA responses by inactivating BR-INSENSITIVE 2 (BIN2), which inhibits the redox-sensitive clade I TGAs in Arabidopsis. We found that both BR and the BIN2 inhibitor bikinin synergistically increase SA-mediated physiological responses, such as resistance to Pst DC3000. Our genetic and biochemical analyses indicated that BIN2 functionally interacts with TGA1 and TGA4, but not with other TGAs. We further demonstrated that BIN2 phosphorylates Ser-202 of TGA4, resulting in the suppression of the redox-dependent interaction between TGA4 and NPR1 as well as destabilization of TGA4. Consistently, transgenic Arabidopsis overexpressing TGA4-YFP with a S202A mutation displayed enhanced SA responses compared to the wild-type TGA4-YFP plants. Taken together, these results suggest a novel crosstalk mechanism by which BR signaling coordinates the SA responses mediated by redox-sensitive clade I TGAs.
基金funded by the National Natural Science Foundation of China(31571722 and 31971984).
文摘IQ67-domain(IQD)proteins function in plant defense and in organ development.The mechanisms by which they influence cotton fiber development are unknown.In the present study,GhIQD10 was expressed mainly in the transition period of cotton fiber development,and GhIQD10-overexpression lines showed shorter fibers.GhIQD10 interacted with GhCaM7 and the interaction was inhibited by Ca^(2+).In in vitro ovule culture,Ca^(2+)rescued the shorter-fiber phenotype of GhIQD10-overexpression lines,which were insensitive to the Ca^(2+)channel inhibitor verapamil and the Ca^(2+)pool release channel blocker 2-aminoethoxydiphenyl borate.We conclude that GhIQD10 affects cotton fiber elongation via Ca^(2+)signaling by interacting with GhCaM7.Brassinosteroid(BR)biosynthesis and signaling genes were up-regulated in GhIQD10-overexpression lines.Fiber development in these lines was not affected by epibrassinolide or the BR biosynthesis inhibitor brassinozole,indicating that the influence of GhIQD10 on fiber elongation was not associated with BR.
文摘Brassinosteroids (BRs) and polyamines (PAs) are widely used to overcome abiotic stresses including salinity stress (NaCl) in plants. In the present investigation, we evaluated the co-application efficacy of 24-epibrassinolide (EBR, a highly active BR) and putrescine (Put, a PA) on the NaCl stress (75 mM and 150 mM) tolerance of Lycopersicon esculentum L. cv. kuber geeta plants. A small rise in protein content was recorded under salinity stress in comparison with untreated control. The NaCl stress was found to significantly enhance the activities of guaiacol peroxidase (GPOX) and superoxide dismutase (SOD);while decline in catalase (CAT) activity was recorded when compared with the untreated control. Salinity stress both at 75 mM and 150 mM was able to cause significant membrane damage as evidenced by an increase in the level of malondialdehyde (MDA) content over untreated control. The EBR and Put co-applications were able to improve protein content in NaCl stressed plants over only NaCl stressed plants. The co-applications of EBR and Put were able to significantly enhance the activities of CAT, SOD and GPOX in L. esculentum under salinity stress (75 mM and 150 mM) when compared with NaCl stressed plants alone. Major decline in the MDA level recorded for EBR and Put co-applications under NaCl stress revealed reduced membrane damages when compared with NaCl stressed plants alone. Our findings provide evidence that EBR and Put co-applications are effective in amelioration of NaCl stress in L. esculentum. Thus co-application potential of EBR and Put may acts an eco-friendly approach towards NaCl stress mitigation in economically important crops.
文摘Brassinosteroids (BRs) are a large group of polyhydroxy steroids, which regulate numerous aspects of plant growth and development, including stem elongation, leaf bending, tracheary element differentiation, stress protection and photomorphogenesis. Recent studies indicate antigenotoxic and anticancerous activities of these compounds. The role of natural BRs in H2O2 (hydrogen peroxide) -induced DNA damage in human lymphocytes is still unknown. The present study reports the presence of Castasterone from leaves of Centella asiatica, an important medicinal herb commonly used as a memory enhancer and immunomodulator. CA50 fraction isolated from Centella asiatica was characterized as Castasterone by electrospray ionization mass spectral data with standard Castasterone. An attempt has been made to study antigenotoxic activity of the isolated Castasterone against H2O2 -induced DNA damage in human blood lymphocytes using Single cell gel electrophoresis assay (Comet Assay). Castasterone at 10–9 M concentration proved to be effective in diminishing the DNA damage by 89.42 %.
文摘ebisu dwarf (d2) is a mutant caused by mutation in a rice brassinosteroid biosynthetic enzyme gene, CYP90D2/D2, thereby conferring a brassinosteroid-deficient dwarf phenotype. Three newly isolated d2 alleles derived from a Nippon- bare mutant library (d2-3, d2-4, and d2-6) produced more severe dwarf phenotypes than the previously characterized null allele from a Taichung 65 mutant library, d2-1. Linkage analysis and a complementation test clearly indicated that the mutant phenotypes in d2-6 were caused by defects in CYP90D2/D2, and exogenous treatment with brassinolide, a bioactive brassinosteroid, rescued the dwarf phenotype of three Nipponbare-derived d2 mutants. However, the content of endogenous bioactive brassinosteroid, castasterone, and the expression of brassinosteroid-response genes indicated that partial suppression of the brassinosteroid response in addition to a brassinosteroid deficiency has occurred in the Nipponbare-derived d2 mutants. Based on these results, we discuss the possibility that wild-type Nipponbare has some defects in an unknown factor or factors related to the brassinosteroid response in rice.
文摘Leaf inclination,a component of crop architecture,influences photosynthetic efficiency and planting density.Various factors,particularly the phytohormones auxin and brassinosteroids(BRs),function in regulating lamina joint bending,and understanding of the genetic control of leaf inclination will help to elucidate the relevant regulatory network.Screening a rice T-DNA insertion population revealed a mutant that was insensitive to auxin and displayed an enlarged leaf angle due to increased cell length on the adaxial side of the lamina joint.Genetic analysis revealed that the increased leaf inclination was caused by T-DNA insertion in the promoter region of OsIAA6,resulting in elevated OsIAA6 expression.Further study showed that OsIAA6 interacts with OsARF1 to suppress auxin signaling and regulates leaf inclination.OsIAA6 mediates the BR effects on lamina joint development,and OsBZR1,the key transcription factor in BR signaling,binds directly to the promoter of OsIAA6 to stimulate its transcription.These results indicate the roles of the OsIAA6-OsARF1 module in regulating rice leaf inclination and suggest the synergistic effects of the phytohormones auxin and BR.
基金supported by the National Key Research and Development Program of China (2018YFD1000706, 2018YFD1000700)the National Natural Science Foundation of China (91417313, 31970313)the Department of Education of Hebei Province (SJ2016012)。
文摘Two potential BRASSINAZOLE RESISTANT 1 (BZR1) homologs were downregulated by brassinosteroids(BRs) in Setaria italica roots.Functional analysis showed that BR regulates the dephosphorylation and nuclear localization of Si BZR1 and that Si BZR1 binds conserved BZR1-recognizing cis elements.In comparison with the wild type,Si BZR1-overexpressing S.italica seedlings were more sensitive to BR-inhibited primary root growth and drought stress,indicating that Si BZR1 is a positive regulator of BR signaling and a negative regulator of drought tolerance in S.italica.PLETHORA-LIKE 1 (Si PLT-L1) was found to be a direct target gene of Si BZR1 in S.italica roots.The expression of Si PLT-L1 was downregulated by Si BZR1.Si PLT-L1-overexpressing S.italica was less sensitive to BR-inhibited root growth and more tolerant to drought stress,possibly owing to the upregulation of drought-inducible Dehydrin-family genes.
