| Wheat Stripe rust caused by Puccinia striiformis f.sp.tritici is an important fungal disease in wheat,which damages wheat all year round and seriously threatens the safety in wheat production.In view of the special geographical location,Tibet wheat growing area where wheat stripe rust outbreaks frequently is isolated from the inland,as a result,loss in wheat production is great.Therefore,the analysis of population genetic and virulence races composition of Puccinia striiformis in Tibet has important guidance for the prevention and control of the disease in Tibet,where is a relatively independent epidemic area of wheat stripe rust,and the rational distribution of rust resistance genes in this region.150 monosporum strains isolated from Tibet were the research objects in this study,two sets of differentials' hosts,Chinese differentials and international near-isogenic line differentials,were used to identify the virlent phenotype.and KASP-SNP marker biotechnology is applied to identify the molecular genotypes Puccinia striiformis in Tibet.the results are as follows:1.Results based on Chinese differentials(1)physiological races showed that 19 known races of Puccinia striiformis and 11 unknown races were identified;the epidemic group is Hybrid46 pathogenic group with a frequency of 42.67%,Hybrid46-7 is the dominant races,mainly popular in the western of Mainling County,with a frequency of 26.67%.The second place is the pathogenical races type before CYR 27,with a frequency of 39.33%,in which CYR23 has the highest frequency with 14.67%.Special races such as CYR10 that have not appeared in the past decade is found;it is worth noting that the third highest frequency races are G-22,with a frequency of 6.67%,the main race CYR34 distributed in Mainling County is first discovered.(2)Virlence gene analysis results showed that the frequencies of virulence genes V1,V3,V3 b,V4b,V6,V9,VA corresponding to Fengchan 3,Danish 1,Hybrid46,Trigo-Eureka,Lovlin 10/13,Funo are 95.90%,94.90%,49.30%,62.50%,53.70%,and 99.40%.Explain that Fengchan 3,Danish 1,Funo have lost effective resistance to stripe rust in Tibet,which is consistent with previous studies;while V6 and V9 have decreased frequencies comparedwith previous researchs.(3)Virlence diversity analysis showed that the highest diversity index of Nei's(Hs)region is the eastern of Mainling County,which is 0.222,and the second highest region is Luozha County,which is 0.197.The lowest region is the western Mainling County.(4)The results of cluster analysis showed that the population genetic similarity coefficient ranged from 0.79 to 1.00.The phenotypic clustering of the population of Puccinia striiformis can be divided into three groups.One is that the Bayi District and Mainling-A group;the second is a group of similar Bomi County strains and the Luoza County strains;the third is the group consisting of the western Mainling County.Among them,the western Mainling County is quite different from the other two groups.2.Results based on the near isogenic line Differentials(1)Differentials test showed that 88 physiological races were identified,of which 19 races with more than 2 strains.A race with a octal value of 400021 has the highest frequency,with 10%,and the races with octal values 541223,500021,and 561223,have frequencies of 8.7%,5.3%,and 5.3%,respectively.(2)Virlence gene analysis showed that 150 single-spore strains were resistant to Yr5 and Yr15,indicating that the resistance genes Yr5 and Yr15 still have highly resistant;The virlence frequencies of Yr1,Yr3,Yr9,Yr44,YrTye and Yr31 in 5 regions in Tibet all exceeded 80%,indicating that these resistance genes have no effective resistance in Tibet.(3)Virlence diversity analysis showed that the the eastern Mainling County has the virlence diversity,with a Hs 0.167,and the second highest is the Bayi region,which is0.128.Bome and Luozha County have low virlence diversity.(4)Clustering analysis showed that the population genetic similarity coefficient ranged from 0.89 to 0.97.The phenotypic clustering of the stripe rust population in Tibet could be divided into three groups,which was consistent with the virlence clustering results based on Chinese Differentials.3 Results based on SNP molecular markers(1)Structure population analysis showed that the best K value of 150 Tibetan strains and 23 western Yunnan strains is 4,and the western Yunnan population is relatively independent from the Tibetan population.The Tibetan strains are divided into 3 groups,the western Mainling County population,Luozha County and Bomi County population,theeastern Mainling County and Bayi District population,the group of Bomi and Luozha County and the eastern f Mainling have certain similarities.(2)Discriminant analysis of principal components analysis found that the scatter plot distribution of 150 Tibetan strains and 23 western Yunnan strains is consistent with the results of the Structure group analysis.The western Yunnan population and the Tibetan population were relatively independent;DAPC Tibetan strains,it is found that the Tibetan strains are divided into 3 groups,the western Mainling County population,the eastern Mainling County and Bayi District population,the Bomi and Luozha County population.and the western Mainling County population is relatively independent of the other two groups,and the eastern Mainling County and Bayi Districtpopulation and Bomi and Luozha County population have certain similarities.(3)Molecular cluster analysis found that 150 monosporum strains in Tibet were roughly divided into three groups.According to the cluster analysis of geographical groups,the populations of Luozha County and Bomi County were similar to the population of the eastern Mainling County.The western Mainling County population is relatively independent.(4)The average genetic diversity value(GD)at the species level is 0.2645,and the polymorphic information(PIC)is 0.2148.The genetic diversity of the five regional populations indicated that the genetic diversity of the eastern Mainling County is the highest.The second highest is the Luoza County strain,followed by the Bomi County strain,the Bayi District and the weatern Mainling County.This is different from the virlence diversity analysis.(4)Gene flow analysis revealed that there is a high degree of genetic communication between Luozha County and Bomi County,there is moderate gene communication between Luozha County and the eastern Mainling County,between Bayi and the eastern Mainling County. |
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