Transcriptome Analysis Of The Interaction Mechanism Of Wheat High-temperature Resistance To Stripe Rust In Xiaoyan 6 And Functional Characterization Of Related Genes

Wheat stripe rust caused by Puccinia striiformis f.sp.tritici（Pst）,is one of the important epidemic diseases of wheat（Triticum aestivum）around the worldwide.It is proved by research and practice that growing non-race specific and durable wheat resistant cultivars is effective strategy to manage stripe rust.The wheat cultivar Xiaoyan 6（XY 6）with high-temperature resistance to Pst has the advantaged of low infection type and durable resistance,which is controlled by major genes and temperature-sensitive minor genes.However,the molecular mechanisms of high-temperature resistance were not clear so far.In this research,wheat cultivar XY 6 and Pst race CYR32 were chosen as materials;RNA-seq,q RT-PCR and virus-induced gene-silence（VIGS）were used to characterised the differentially expressed genes（DEGs）;therelated-signaling pathwayand the host defense responses were analysized during the process of host high-temperature resistance to Pst.The aim is to preliminarily illustrate the molecular mechanism of high temperature rust resistance in wheat cultivar XY 6 to Pst,and to establish foundation for the discovery of durable resistance gene and provide materials or idea for molecular breeding.The main results were as followings:1.The optimal conditions for high-temperature seedling plant（HTSP）resistance expression to stripe rust in XY 6 was 20℃for 24 h.2.To identify differentially expressed genes（DEGs）in HTSP resistance,30 c DNA libraries were obtained from XY 6 exposed to different temperature treatments and analysed by Illumina technology.The CDMC strategy was confirmed the optimization assembly,and445226 transcriptswere obtained,N50 was 1849 bp length.Compared to the constant normal（15℃）and higher（20℃）temperature treatments,1395 DEGs were identified relating to HTSP resistance.These DEGs were mainly mapped on B genome of Chinese Spring wheat genome.These 1395 DEGs were enriched in ribosome,plant-pathogen interaction and glycerolipid metabolism pathways,and some of them were identified as hub proteins（phosphatase 2C10）,resistance protein homologs,WRKY transcription factors and protein kinases.3.Twenty-five DEGs involved in HTSP resistance of wheat were identified in Pst by transcriptome analysis.Functional annotation and classification found that these DEGs were related to membrane protein,m RNA binding protein,cell membrane transport and synthesis of cell nitrogen compounds.A high expression candidate effector protein PSTG＿13342 was identified and cloned.In addition,five DEGs were identified from constant high temperature stress,including a senescence associated protein（PSTG＿16995）with the expressionof 35 fold up-regulated.4.TaRPS2 positively regulates wheat HTSP resistance to Pst,which was significantly enriched in the pathway of interaction between plants and pathogens by transcriptome analysis of wheat.The length of TaRPS2 is 3515 bp,coding 960 amino acids.The expression level of TaRPS2 was significantly increased when exposured to high temperature during the initial symptom-expression stage of Pst infection.Silencing TaRPS2 led to enhanced susceptibility to Pst（in terms of the longer in the length of uredinial pustules and the decrease on the number of necrotic cells）than non-silenced when exposed to high temperature during the initial symptom-expression stage of Pst infection.However,there was no difference between the silent and non-silence treatments in constant normal temperature and high temperature treatments,respectively.The expression levles of TaRPS2 were all increased at0.5 h when treated with SA and H₂O₂respectively.Moreover,TaRPS2 showed higher expressionin leaf than in root or stem.