| Stripe rust, caused by Puccinia striiformis f. sp. tritici(Pst),is the most important fungi disease on wheat in the world, especially in China.. Wheat stripe rust can be spread remotely by airflow and often leads to nation wide epidemic. Wheat stripe rust from the western Pst hot-spot areas, such as Tianshui and Longnan area of Gansu province, often spreads to eastern areas through Shaanxi province. Moreover, Shaanxi province is also the winter reproductive and over-winter area for wheat stripe rust. Therefore, it is very important for disease epidemic forecasting and wheat breeding to monitor Pst population structure in Shaanxi province.In this study, 86 stripe rust samples collected from Ningqiang, Longxian, Ziyang and Hantai in Shaanxi province in 2015 were identified on 23 known Yr gene lines. Also, population genetic diversity of 68 Pst isolates collected from five wheat cultivars planted in Ningqiang experiment field in 2014 was analyzed with 15 pairs of SSR primers. The results were showed as follows:1.The virulence frequencies of 86 tested stripe rust isolates on Yr resistance genes Yr1,Yr2,Yr3,Yr7,Yr9,Yr13,Yr17,Yr18,Yr26,Yr27,Yr30,Yr31,Yr32,Yr43 and Yrsp were all above 80%. And the virulence frequencies on Yr6, Yr44 and Yr4 b and that on Yr8, Yr10 and Yr24 were 20% ~80% and below 20%, respectively. None of Pst isolates were virulent to Yr5 and Yr15.Morevoer, Pst isolates collected from different districts were also different in virulence frequencies and distributions.2. A total of 59 Pst pathotypes were identified on 23 known Yr gene lines. And the number of pathotypes in Ningqiang, Longxian, Ziyang and Hanzong were 33, 24, 8 and 4, respectively. The virulence frequencies on resistance genes Yr1, Yr2, Yr3, Yr7, Yr13, Yr17, Yr18, Yr26, Yr27, Yr30, Yr31, Yr32, Yr43, Yr44, Yr4 b and Yrsp were higher than that on other Yr resistance genes. And avirulence frequencies to Yr5, Yr6, Yr8, Yr9, Yr10, Yr15, Yr24 were 15.1%, which were detected on all of four regions.3. The virulence diversity of Pst population in Shaanxi province was high. The number of polymorphic loci(NP)and the percent of NP were 21 and 91.30%, respectively; the Nei’s gene diversity(H) and Shannon’s information index(I) were 0.3150 and 0.4731, respectively. The virulence diversity among different Pst populations had significant difference. And the genetic distance(GD) and genetic identity(GI) in different populations were 0.0158~0.1433 and 0.8665~0.9843, respectively.. The virulence diversity of Ningqiang Pst populationwas the highest, and the second is Longxian Pst population and Hantai Pst population was the lowest.4. The virulence diversity of Pst population among different wheat cultivars in Ningqiang and Longxian was high and has significant differences. For Ningqiang Pst population,the number of polymorphic loci(NP) and the percent of NP were 22 and 95.65%, respectively; the Nei’s gene diversity(H)and Shannon’s information index(I) were 0.3260 and 0.4929, respectively; the range of genetic distance(GD) and genetic identity(GI) were 0.0522-0.22340 and 7998-0.9492, respectively.For Longxian Pst population,the number of polymorphic loci(NP) and the percent of NP were 17 and 73.19%, respectively; the Nei’s gene diversity(H) and Shannon’s information index(I) were 0.2365 and 0.3583, respectively; and the range of genetic distance(GD) and genetic identity(GI) were 0.0534-0.1868 and 0.8296-0.9480, respectively.5. The genetic diversity of Pst population from different wheat cultivars in Ningqiang was high and has significant differences. The number of polymorphic loci(NP) and the percent of NP were 73 and 97.33%, respectively; the average number of alleles(Na) per locus was 1.9733; the effective number of alleles(Ne)was 1.2858; the Nei’s gene diversity(H) and Shannon’s information index(I) were 0.1776 and 0.2854, respectively. And the genetic identity(GI) in Pst populations on different wheat cultivars was 0.9771~0.9997.With high GI, there maybe an gene flow among different Pst populations. |
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