The Study About The Role Of Berberis In Tibet Displaying In Virulence Variation In Wheat Stripe Rust

Wheat stripe rust caused by Puccinia striiformis f. sp. tritici (Pst), is one of the mostimportant diseases of wheat in wheat production region worldwide. Low temperature favorsfor the disease. Wheat cultivar with resistance to stripe rust has been proved to be the mosteconomical, effective and environment-friendly strategies for control of the disease. However,rapid virulence changes in the Pst population have rendered many previous resistant cultivarsto be susceptible, resulting in devastating epidemics. Stripe rust is also a serious diseases oncereals including barley and wheat that are the staple crops in Tibet because of its widespreadand damage, In recent years, resistance of winter cultivar Feidong in Linzhi of Tibet hasovercome to be susceptible.Previous studies reported that pathogen variability of Pst in virulence also attributed tofunction of sexual hybridization on barberry (Berberis spp.) in nature. In this study, fieldsurvey of barberry and natural infection by rust fungi in “hotspot” regions for the stripe rust inLinzhi, Tibet were performed. Leaf samples with aecia were collected and detected based onPCR molecular examination. The results indicated that that percentage of P. striiformis f. sp.tritici (Pst) and P. graminis f. sp. tritici (Pgt) were56.7%and5.5%among200DNA ofaecial samples, respectively. Simultaneously, Aecial samples were used used for inoculationon seedings of wheat cultivar Mingxian169susceptible for Pst for Pst isolation. Fianally,four Pst isolates, and three Pgt isolates were recovered from rust-infected barberry,accounting for0.34%(Pst), and0.26%(Pgt). Tests of virulence based on Chinese differentialhosts demonstrated that four of the Pst isolates had virulence patterns different from allpreviously reported races. Furthermore,25single-uredinium (SU) isolates derived from thefour Pst isolates presented high virulence diversity ranged from18.0%to25.0%, indicatingthat the diverse isolates were produced through sexual reproduction of Pst on barberry plants.Therefore, barberry plants not only serve as alternate hosts for stripe rust pathogen of wheat inTibet, and also the sexual cycle of the fungus on barberry plays an important part in virulencevariation of Pst and diseases epidemic. Function of barberry in occurrence of wheat stripe rust,and intergrated control of the disease in Tibet should be considered.