The Identification And Function Analysis Of Genes In Response To High Temperature Stress In Arabidopsis

Temperature is one of the main limiting factors affected plant growth and natural distribution.In the long-term evolution process plants formed resistant mechanism in response to temperature stress.Previous results demonstrated that epigenetics can be involved in the resistance mechanism of plant response have to temperature stress,and chromatin structure change can influence the expression regulation of genome which was controlled by the histone post-translation modification and DNA methylation.In higher organisms,DNA methylation modification is an important epigenetic marker regulating gene expression.The approach of RNA directed DNA methylation(RdDM)is one of the important mechanisms in response to abiotic stress that regulate gene expressing.The main results are as follows:Firstly,we analyzed the chip data of temperature stress,epigenetic map of Arabidopsis and siRNA database and screened the gene of AT2G21150 encoding XCT.We then detected the DNA methylation in the promoter region and the expression level of the gene by using Bisulfite Sequencing PCR(BSP)and qRT-PCR.The expression of XCT was induced by high temperature stress and regulated by epigenetics.By using the T-DNA insertion mutants of AT2G21150 from the ABRC,we found that the mutant showed sensitive to high temperature stress at seed germination and seedling stages.Analysis of the temporal and spatial expression patterns of XCT revealed that the mRNA level was highest in the seeds,and was obviously induced by high temperature.Under the high temperature stress condition,the methylation level was significantly decreased and the accumulation of 24nt-siRNA was reduced in promoter region of XCT.It is speculated that the RNA-directed DNA methylation pathway can promote the expression of genes by lowering the level of methylation.In vitro transient transformation experiments in tobacco further confirmed that RNA-directed DNA methylation pathway was involved in high temperature response in plants.In addition,we screened the EMS-mutageneted Arabidopsis mutant library,and identified a heat resistant mutant named h46.The mutant had no obvious difference with the wild type under short day growth condition.However,under the condition of long day,it showed the phenotype of plant dwarf and more anthocyanin accumulation.During the seed germination stage,h46 showed a heat sensitive phenotype after high temperature treatment,while in the seedling stage and mature plant stage,it showed a heat resistant phenotype.By map-based cloning approach,we detected that the mutation was located on chromosome 1.The mutant h46 will provide a insight of the relationship between plant and high temperature stress.