Genetic Diversity Analysis Of Phytophthora Infestans Population Collected From Resistance Evaluation Nursery Of Potato

Late blight, caused by the Oomycete Phytophthora infestans, has been one of the mostdevastating diseases of potato (Solanum tuberosum) in the world. Analysis of the populationgenetic variation of P. infestans is essential for understanding the disease epidemiology anddeveloping disease control measures. A range of molecular genetic markers including SimpleSequence Repeat (SSR), have been widely used for studying genetic variation anddifferentiation of pathogen populations. In this study, mating type determination and a set of9SSR markers were used for assess genetic diversity of P. infestans population in a germplasmnursery in Tianshui of Gansu province in2012and2013. This study will set up the foundationfor Potato late blight control and prevention.The results are as follows:1. A total of291and341were collected from resistance evaluation nursery of potato in2012and2013, respectively.2. The ratio of A1, A2and Self-fertility mating type was2.75%,42.27%and54.98%in2012. The ratio of A1, A2and Self-fertility mating type was6.16%,66.57%and27.27%in2013. The majority isolates were A2mating type, followed by self-fertile mating type. A2and self-fertile mating type have collected from most of the varieties, A1mating type lowfrequency.3. Using9SSR markers,92genotypes were detected among276P. infestans isolates.Three genotypes were found to be dominant(38.04%), comprising34,31and20isolates,respectively. P. infestans isolates of different genotypes were isolated from the same potatolines. Isolates of unique genotypes were detected from many potato lines. The analysis ofmolecular variance (AMOVA) of SSR genotype data revealed that the majority of the geneticvariation (99%) was found within populations and only1%genetic variation was observedamong populations (P<0.01).