Population Structure And Analysis Of Puccinia Striiformis F.SP. Tritici Race In Tibet And Shaanxi In2010and2011

Wheat stripe rust, caused by Puccinia striiformis f.sp. tritici, is one of the most importantdiseases of wheat in China. New races (pathogenic types) continue to evolve, leading topartial or complete loss of resistance in current cultivars. Since1950s, resistance possessed inpopular cultivars to stripe rust has been overcome for at least seven times. Monitoring Pstraces population dynamics and accurately predict the dominant population can provideimportant scientific basis for prediction of wheat stripe rust and also assist breeders indeveloping strategies for breeding cultivars with durable resistance. Wheat stripe rust is themost important disease on winter wheat in Tibet, an independent region of wheat cultivationin China. For a long time, with the traffic and geographic position limit, there is noinformation on population structure of Pst race in Tibet; Shaanxi, located in the binging site ofLongnan region and the huanghuai winter wheat region, is an important bridge zone for wheatstripe rust spreading from east to west. In this research, we have completed the monitoring ofPst races and analysis of population structure on801Pst samples come from Tibet, ShaanxiProvince and Tianshui region respectively in2010and2011.The results were obtained asfollows:1.391Pst samples from Tibet were identified in2010and2011, monitoring respectively19and26races(types), many types of races including CYR17、CYR20、CYR31、CYR32、CYR33、Su11-1、Su11-4、Su11-6and so on, were found. Dominant races were CYR32andCYR33, dominant population was Shui11group. In Tibet, compared with the results ofSichuan, Yunnan, and Qinghai province, the races before CYR28have a significantly higherproportion, therefore, Pst races in Tibet varies relatively slowly. The structure of Pst in Tibetis similar with that in Sichuan province, closely followed by Yunnan province and Qinghaiprovince comes last. For major races, Tibet has great differences with Qinghai province andsimilarities with Sichuan and Yunnan province. It can be speculated that Pst in Tibet has itsown uniqueness and might be frequently exchanged with in Sichuan and Yunnan province, little exchanged with in Qinghai province. The analysis of virulence frequency in Tibetindicates that he cultivars carrying genes Yr1、Yr3、Yr6、Yr9、YrA had become susceptible tothe prevalent races. The standard of virulence frequency that Pst in Tibet acts on majorresistance genes in stripe rust is equivalent to the national level. And for some certainresistance genes, the standard of virulence frequency is lower than other areas in China. It justproves that the Pst in Tibet varies slower than that in surrounding regions.2.310Pst samples from Shaanxi province were identified in2010and2011, monitoringrespectively22and13races(types),they are mainly CYR32, CYR33, Su11-4and Su11-5. ThePst race group in Shaanxi province is relatively simple and it mainly consists of Hybrid46andShui11. Besides, the structure of Hybrid46is simple, the dominant races are CYR32andCYR33. In2010, the Pst race’s frequency, component and dominant race in Guanzhong,Shaanxi province and Tianshui Gansu province have many similarities. Therefore, it hasshown that Pst in these two areas have close relationships.