Population Genetic Structure Of Puccinia Triticina In Several Provinces Of China

Wheat leaf rust, caused by Puccinia triticina, is one of the most prevalent and widespread disease that threats to the safety of wheat production in China. Therefore, it is essential to be aware of the structure of wheat leaf rust population for understanding the epidemic characteristics, and providing information for leaf rust control. Puccinia triticina isolates were collected from Xinjiang Uygur Autonomous Region, Henan Province, Gansu Province and Yunnan Province. We analysed the virulence of Puccinia triticina with thirty-three differential hosts. Meanwhile, we analysed the moelcular genetic structure of Puccinia triticina isolates from four locations with four partial conserved genes(RPB1, HSP70, RPB2 and TUB).(1) The virulence structure of P. triticinaWe identified 45 pathotypes mainly including THT, NHJ, PHF, PHT. Virulence frequency to Lr2 b, Lr2 c, Lr3 bg, Lr10, Lr14 a, Lr14 b, Lr16, Lr17, Lr26, Lr27+31, Lr33, Lr34, Lr35, Lr36 were above 75% among this population, which showing these genes had lost their resistance. The virulence frequencies were less than 30% including Lr9, Lr15, Lr19, Lr24, Lr25, Lr28, Lr29 and Lr42, and these genes showed effective resistance. The virulence frequency to Lr2 a, Lr3 ka, Lr18, Lr23, Lr30, Lr32 and Lr43 varied more than 50%, and indicating the virulence diversity in Gansu and Yunnan population was more diverse than Henan and Xinjiang population. UPGMA dendrogram indicated that the virulence genetic distance between Gansu and Henan population, while it was further betwwen Yunnan population and other 3 populations.(2) The molecular genetic polymorphisms of the four populationsEighty-nine sequences of 3103bp(deletions)combined with four partial sequences was gained and 18 SNPs were identified, moreover, 11 of which were parsimony-informative and 7 were singleton variable, 12 of which were transition and 6 of which were transversion. Generally, there were 49 unique multilocus haplotypes. P. triticina populations of Xinjiang, Henan, Gansu and Yunnan owned 17, 13, 15, 19 multi-locus haplotypes, respectively.(3) The genetic structure of leaf rust populationsThree clusters were grouped for the 89 Lr isolates by Snn and SAMOVA. AMOVA indicated the largest percentage of variance was within populations. Neutrality tests and mismatch distributions showed population expansion and the evolution of P. triticina populations was in line with the neutral theory.(4) Genetic differentiation and gene flow among populationsNetwork of haplotypes indicated the exist of genetic differentiation between isolates from Xinjiang and Gansu. There are significant genetic differences among any regions except of Gansu and Yunnan.We found that gene flow existed among all four populations. More abundant gene flow existed between Henan and Xinjiang population, Yunnan and Gansu population.