Preliminary Analysis Of Wheat Stripe Rust Resistance Gene Yr10 Disease Resistance Pathway

Stripe rust,caused by Puccinia striiformis f.sp.tritici,is a damaging fungal diseases,which imposing great threat to wheat production.However,the prevention of stripe rust is always been passive due to the airflow and constantly mutating of Pst.Production practice and research has been proven that growing resistance cultivars is a economic safest and effective method.Yr10 is an important disease resistance gene,performing resistance to the most popular Stripe Rust.Thus,it is of great significance to investigate the mechanism of Yr10 mediated resistance and signaling pathway for resistance breeding.In this study we study the expression profiles of Yr10 and some disease related genes by QRT-PCR in response to different induces;We determined the endogenous SA in compatible wheat and incompatible wheat in order to investigate the association between Yr10 defence pathway and SA signaling pathway;we analyzed histological characteristics of pathogen development and H2O2 accumulation and hypersensitive response in different interactions.There was a Ta MYB29 screened by Yeast Two-hybrid System which maybe interacting with Yr10 in our lab,so we further verify its function in the interaction between wheat and Pst.The main results were as follow:(1)Yr10 is tissue specific,most of it accumulate in roots and least in spike.Yr10 is induced by stripe rust,it was down-regulated in early stage and peaked at 24 hpi then backed to near 0h level.Pathogenesis-related proteins PR1,PR2 and PR5 were induced by stripe rust and expressed abundantly in the host,but the expression in incompatible host is very fast and tremendous.So the pathogenesis-related proteins may play improtant roles in the downstream of the disease resistance pathway.(2)Yr10 was down-regulated by exogenous hormones ABA,SA,JA,ET at 2hpt,6hpt and significantly up-regulated at 48 hpt when treated with ABA and SA.But endogenous SA increased in the treatment of ABA,it increased 8-fold at 24 hpt and significantly declined at 48 hpt.Though SA was also induced by stripe rust,the trend of SA level is opposite to Yr10 in incompatible interactions.What's more,there was more SA in compatible interactions.The results indicated that SA signaling pathway has a close relation with the disease resistance signaling pathway of Yr10,it helps Yr10 to control the disease resistance.(3)The results of histological analysis in different interaction systems indicated that ROS bursts and cell necrosis increases rapidly from24 phi to 48 hpi and peaked at 96 hpi.In the incompatible interactions,the DAB staining area and necrosis area were smaller,hyphal growth was inhibited,the number of haustorial mother cells and haustoria,the area of colonies,were significantly less than compatible interactions.(4)We cloned the gene which named Ta MYB29.Ta MYB29 distributed in the nucleus of wheat protoplasts in a sub-cellular localization assay and showed a slight self-activation ability in yeast.Besides,Ta MYB29 transcriptional level could be induced with an increase between 12 to 48 hours after exogenous hormone application.When knocking down the transcriptional level of Ta MYB29 by virus induced gene silencing(VIGS),necrosis in incompatible interaction AVS+Yr10 reduced after Pst.inoculated.Furthermore,overexpression of Ta MYB29 through PVX-mediated agrobacterium system could induce programmed cell death(PCD)in tobacco leaves,which indicated that Ta MYB29 promote necroses in plant cells.