| Phytophthora infeatans (Mont.) de Bary, the causal agent of late blight of potato and tomato, continues to be a serious threat to potato production worldwide. The objective of this work was to collect potato late blight samples, isolate the pathogen and determine the mating type of P. infestans in some regions of northwest China. The genetic diversity of P. infestans was assessed using SSR markers. The results are as follows:1. A total of 140 isolates of P. infestans were isolated in northwestern China in years 2007 and 2008.2. A2 mating type isolates were identified in some regions of northwestern China. The frequency of A2 mating type isolates varied among different regions.3. A total of 140 P. infestans isolates from eight different regions were genotyped for genetic diversity and geographical differentiation with eight SSR markers. SSR analysis resulted in the identification of 17 genotypes, of which four genotypes were common. The isolates collected in Qinzhou showed the highest level of genetic diversity with Shannon's Information index = 0.8527 and 5 genotypes detected. Meanwhile, the SSR genotypes detected in Qinzhou population were widely distributed to the remaining seven populations. The genotype distribution and the high level of genetic diversity in the Qinzhou population suggested the presence of exchange of pathogen genotypes between Qinzhou and other different regions by migration. UPGMA cluster analysis indicated that little genetic differentiation was revealed among populations Guyuan, Zhuanglang, Qinzhou , and Xifeng in contrast to a relatively higher level of genetic differentiation among populations of Anding, Gangu, Datong, and Weiyuan. There was no clear correlation between the SSR genotypes and mating types.4. Evaluation of genetic stability showed that the employed 8 SSR markers were mitotically stable in P. infestans through ~44 cell division.
|
PDF Full Text Request