Analysis of interregional dispersal of Puccinia striiformis in China using a coalescent method
J. LIANG (1), Q. Wan (1), Y. Luo (2), Z. Ma (1). (1) China Agricultural University, Beijing, China; (2) University of California-Davis, Davis, CA, U.S.A.
Phylogenetic methods can be used to infer the gene flow and dispersal directions among plant pathogen populations. In this study, a total of 761 isolates of <i>Puccinia striiformis</i> (<i>Pst</i>) were collected from northwestern China covering five provinces (Gansu, Sichuan, Ningxia, Shaanxi and Qinghai), the main areas providing initial inoculum for interregional epidemics in China. The amplified fragment length polymorphism (AFLP) method was applied to obtain molecular dataset for these isolates. A coalescent approach using the likelihood and Bayesian (Migrate-N and BayesAss) was applied to infer the interregional dispersal rates and their directions. Furthermore, 127 representative isolates were used to identify their races. Higher race diversity, genetic diversity and highly significant asymmetric dispersal were detected in Gansu and Sichuan populations than in other three provincial populations, suggesting that Gansu and Sichuan were likely the major potential source of immigrants of <i>Pst</i> in northern and northwestern China. Migration rate estimates based on Migrate-N showed that southern Gansu and northwestern Sichuan populations were the most important contributors as main dispersal source among 9 regional populations. In addition, frequent gene flows from eastern Gansu, Ningxia and Qinghai to other regions were also detected. Sichuan Basin served as the largest destination accepting migrated inoculum from other source regions based on analysis using software BayesAss.
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