Analysis Of Genetic Diversity Of Phytophthora Infestans In Southren Ningxia

Phytophthora infestans lead to late blight of potato, which causes a serious threat for potato production in worldwide.The potato area and output are all the first in the world. It is a critical influence for potato industry if this disease breaks out in a short time. By collecting samples, isolating and purifying the pathogen, we determined the mating type of P.infestans of Ningxia. Also by using SSR molecular markers,we attempted to assess the genetic diversity of P.infestans. The main results as follows:1. A total of 127 isolates of P. infestans were obtained in Ningxia in 2009.2. Mating type determination assay revealed that A2 mating type had been present extensively in Ningxia. Of the isolates collected in Yuanzhou, Jingyuan, Xiji ,Longde and Penyang, A2 mating type accounted for 40%,71%,50%,46.2%,50% respectively.3. A total of 73 isolates of Phytophthora infestans sampled from eight different geographical populations in Ningxia were genotyped for genetic diversity and geographical differentiation with eight SSR markers. SSR analysis resulted in the identification of 57 genotypes. The isolates collected in Jingyuan showed 29 genotypes,of which only two genotypes were mainly,respectively 11.1% and 13.3%. Meanwhile, the SSR genotypes detected in Longde population was 16.,Yuanzhou was 8 and Xiji was 4.There were 36 unique genotypes in all 57 genotypes. The isolates collected in Jingyuan showed the highest level of genetic diversity with Shannon's Information index = 0.5364.4. Comparing with 50 samples that we collected in 2007, the genotypes are different in two years.5. We did not observed oospore of 297 samples.