[Objective] Effect of heat shock factor AtHsfA1a mutation on ascorbate peroxidase under heat stress in Arabidopsis thaliana was studied.[Method] T-DNA inserted mutant of Arabidopsis AtHsfA1a and wild-type plants were used as experimental materials to compare activity of Ascorbate peroxidase (APX,EC 1.11.1.7) in different genotypes under heat stress by using spectrophotometry.The gene expression levels of the Antioxidant enzyme APX of different Arabidopsis genotypes were analyzed under heat stress by using RT-PCR.The binding of AtHsfA1a to the promoter regions of APX were investigated by using chromatin immunoprecipitation(CHIP) in vivo and electrophoretic mobility shift assay (EMSA) in vitro.[Result] The activity of APX in T-DNA inserted mutant of Arabidopsis AtHsfA1 a was less than that in the wild-type plants under heat stress.We also found that the mRNA levels of APX in T-DNA inserted mutant of Arabidopsis were lower than those in wild-type plants.The results showed that the binding of AtHsfA1a to the promoter regions of APX at different degrees existed in vivo and in vitro.[Conclusion] Effect of heat shock factor AtHsfA1 a mutation on ascorbate peroxidase under heat stress in Arabidopsis thaliana was directly regulated the expression of APX by the level of transcription.%[目的]探讨热激因子AtHsfA1a突变对热胁迫中拟南芥抗坏血酸过氧化物酶的影响.[方法]以T-DNA插入AtHsfA1a基因突变拟南芥及野生型植株为材料,采用分光光度法比较热胁迫下不同基因型植株的抗坏血酸过氧化物酶(APX,EC1.11.1.7)活性的变化,RT-PCR法研究AtHsfA1a对APX表达的影响,染色质免疫沉淀技术和凝胶阻滞电泳分析体内外研究AtHsfA1a与APX基因启动子区的结合情况.[结果]在热胁迫下AtHsfA1a基因突变拟南芥植株中的APX的活性低于野生型,且AtHsfA1a基因突变拟南芥植株中的APX的mRNA的相对量低于野生型;体内研究发现在热胁迫下AtHsfA1a基因突变拟南芥植株中未筛选出APX基因启动子区片段,而野生型筛选出APX基因启动子区片段,体外研究发现AtHsfA1a与APX基因启动子区的结合是直接的.[结论]热激因子AtHsfA1a突变对热胁迫中拟南芥APX的影响是从转录调控水平直接影响APX的表达.
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