Plants are vulnerable to heat stress,especially during reproductive development.The heat shock response(HSR)in the cytosol and nucleus,as well as the unfolded protein response(UPR)in the endoplasmic reticulum(ER),are ...Plants are vulnerable to heat stress,especially during reproductive development.The heat shock response(HSR)in the cytosol and nucleus,as well as the unfolded protein response(UPR)in the endoplasmic reticulum(ER),are two mechanisms that enable plants to survive heat stress.Excessive heat or ER stresses lead to cell death when the UPR cannot repair stress damage,but the means by which cell survival or death is determined remains unclear.In this study,we used a genome-wide association study(GWAS)to identify that a cluster of five Immune-associated nucleotide-binding protein(IAN)genes(IAN2 to IAN6)is responsible for variation in heat tolerance at the reproductive stage in Arabidopsis thaliana.These IAN genes have both unique and overlapping functions in the negative regulation of heat tolerance,and their loss of function singly or in combination confers increased heat tolerance,measured by a lower number of barren siliques and a higher seedling survival rate under heat.The loss of rice IAN1 gene function also leads to enhanced heat tolerance,suggesting a conserved function of plant IANs.Transcriptome analysis revealed enhanced expression of HSR and UPR genes,as well as reduced cell death,under heat and ER stress in the mutant of IAN6,a major effect member in Arabidopsis.Furthermore,the IAN proteins were found to promote cell death induced by heat stress,ER stress,and cell death-inducing molecules.Thus,the Arabidopsis IAN genes repress heat tolerance,probably through the HSR and UPR and by enhancing the cell death pathway.The IAN2 to IAN6 proteins are partially localized to the ER,suggesting a direct role in the UPR and UPR-mediated cell death.In addition,a natural IAN6 variant from more heat-tolerant Arabidopsis accessions confers greater heat tolerance and induces less cell death compared with the natural variant from less heat-tolerant accessions.The heat-tolerant IAN6 variant is associated with a higher maximum temperature of the warmest month at its collection sites compared with the heat-sensitive variant.Taken together,these results reveal an important role of Arabidopsis IAN2 to IAN6 genes in the regulation of the HSR,UPR,and cell death,and suggest that their natural variations have adaptive functions in heat tolerance.展开更多
基金This work is supported by the National Science Foundation of China(NSFC)(31700223 and 31670269)the National Science Foundation of the USA(IOS 1353738)+5 种基金Fundamental Research Funds for the Central Universities(FRFCU)(KJQN201807)the International Postdoctoral Exchange Fellowship Program(no.20160048)from the Office of the China Postdoctoral CouncilOpen Funds of the State Key Laboratory of Plant Physiology and Biochemistry(SKLPPBKF1501)Natural Science Foundation of Jiangsu Province,China(BK20180525)the Jiangsu Collaborative Innovation Center for Modern Crop ProductionCyrus Tang Innovation Center for Crop Seed Industry.
文摘Plants are vulnerable to heat stress,especially during reproductive development.The heat shock response(HSR)in the cytosol and nucleus,as well as the unfolded protein response(UPR)in the endoplasmic reticulum(ER),are two mechanisms that enable plants to survive heat stress.Excessive heat or ER stresses lead to cell death when the UPR cannot repair stress damage,but the means by which cell survival or death is determined remains unclear.In this study,we used a genome-wide association study(GWAS)to identify that a cluster of five Immune-associated nucleotide-binding protein(IAN)genes(IAN2 to IAN6)is responsible for variation in heat tolerance at the reproductive stage in Arabidopsis thaliana.These IAN genes have both unique and overlapping functions in the negative regulation of heat tolerance,and their loss of function singly or in combination confers increased heat tolerance,measured by a lower number of barren siliques and a higher seedling survival rate under heat.The loss of rice IAN1 gene function also leads to enhanced heat tolerance,suggesting a conserved function of plant IANs.Transcriptome analysis revealed enhanced expression of HSR and UPR genes,as well as reduced cell death,under heat and ER stress in the mutant of IAN6,a major effect member in Arabidopsis.Furthermore,the IAN proteins were found to promote cell death induced by heat stress,ER stress,and cell death-inducing molecules.Thus,the Arabidopsis IAN genes repress heat tolerance,probably through the HSR and UPR and by enhancing the cell death pathway.The IAN2 to IAN6 proteins are partially localized to the ER,suggesting a direct role in the UPR and UPR-mediated cell death.In addition,a natural IAN6 variant from more heat-tolerant Arabidopsis accessions confers greater heat tolerance and induces less cell death compared with the natural variant from less heat-tolerant accessions.The heat-tolerant IAN6 variant is associated with a higher maximum temperature of the warmest month at its collection sites compared with the heat-sensitive variant.Taken together,these results reveal an important role of Arabidopsis IAN2 to IAN6 genes in the regulation of the HSR,UPR,and cell death,and suggest that their natural variations have adaptive functions in heat tolerance.