Genetic Diversity Analysis And Virulence Structure Of Puccinia Striiformis F.sp.tritici In Six Provinces Of Northwest And Southwest China

Wheat stripe rust is one of the most serious diseases in Chinese.It has the characteristics of rapid spread,strong epidemic and wide occurrence range.Stripe rust spores can spread to various wheat production areas through air flow,which poses a serious threat to wheat production safety.Northwest and southwest China is an important endemic area of wheat stripe rust,which provides the environment for wheat stripe rust over summer and winter,and is the source of disease epidemic in the eastern wheat region.It is of great significance to analyze the genetic structure and gene flow of stripe rust populations in northwest and southwest China,and to analyze the genetic relationships among the populations.In this study,235 stripe rust isolates were collected and isolated from 6 provinces in northwest and southwest China(Xinjiang,Gansu,Ningxia,Shaanxi,Sichuan and Yunnan)during the 2020-2021 and 2021-2022 wheat growing seasons.The Chinese differentials and Yr single-gene lines were used to monitor the population virulence structure.20 pairs of KASP-SNP primers were used for genotyping.The genetic relationship of stripe rust population in southwest China was analyzed by combining the infection phenotype and genotype data.The main results are as follows:1.Based on the Chinese differentials results of wheat stripe rust,65 races were detected from 118 isolates of Shaanxi,Ningxia,Gansu and Xinjiang in 2021,which mainly belonged to Suwon 11(44.07%),Guinong 22(34.75%)and Hybrid46(11.86%).The frequency of CYR32 was the highest(5.08%),followed by CYR33(4.24%),SU11-002(4.24%)and G22-168(4.24%).In 2022,51 races were detected from 117 isolates of Shaanxi,Sichuan and Yunnan.They belonged to Guinong 22(42.74%),Hybrid46(34.19%),Suwon 11(17.09%)and Zhong 4(5.98%).Among them,the frequency of CYR34,CYR32 and CYR33 ranked the first three,16.24%,16.24% and 5.98%,respectively.2.Based on identification results of the Yr single-gene lines results of wheat stripe rust,a total of 105 pathogenic types were detected in 2021,with the highest occurrence frequency of VP16 and VP26,which were 3.39% and 2.54% respectively.Among them,VP16 was the dominant pathogenic type in Ningxia,while VP26 was only distributed in Shaanxi and Gansu.A total of 105 pathogenic types were detected in 2022,among which VP120 had the highest occurrence frequency(4.27%)and was distributed in Shaanxi,Sichuan and Yunnan provinces.VP9,VP129 and VP136 were followed by 2.56%.The 2021 and 2022 stripe rust have 6 identical pathogenic types,namely VP6,VP9,VP26,VP28,VP29 and VP33.Among them,VP26 is the most widely distributed and can be detected in Shaanxi and Gansu in 2021 and Sichuan and Yunnan in 2022.3.The results of virulence diversity showed that the population of stripe rust was different among provinces,and Gansu province had the highest virulence richness Nei’ s diversity index,Kosman index and Stoddart index were the highest in Sichuan population,while Shannxi population had the highest Shannon index and Gleason index in 2021.These two provinces had the highest virulence diversity among all regions.The results of cluster analysis showed that the populations were grouped into different branches in the past two years.The genetic distance between Gansu and other provinces was greater than 0.1,and the virulence structure was different.The genetic distance between Sichuan and Yunnan populations was less than 0.05,and the virulence structure was consistent.4.20 pairs of KASP-SNP primers were used to genotype 235 isolates from 6provinces,and 183 multi-locus genotypes were identified.The genetic diversity of Yunnan population was the highest,followed by Xinjiang population.The genetic background of Shaanxi population is similar to that of Gansu population and Ningxia population,Xinjiang population is relatively independent,and Yunnan population is similar to that of Northwest China.The gene exchange between Shaanxi and Gansu,Shaanxi and Ningxia,Gansu and Ningxia,Sichuan and Yunnan was frequent,with Nm>4;Shaanxi and Yunnan,Ningxia and Yunnan,Gansu and Yunnan,Shaanxi and Sichuan had moderate gene exchange,with 1<Nm<4.The genetic distance between Shaanxi and Sichuan,Gansu and Ningxia populations was small.Genetic variation exists mainly within populations.