Population Genetic Analysis Of Phytophora Infestans In China

Potato late blight caused by Phytophthora infestans(Mont.)de Bary,is the most devastated disease of potato worldwide,and the most serious threat to potato production in China.It is important to study the pathogen population for monitoring the occurrence and epidemic of potato late blight,and lay a foundation for effective control strategies.In this study,we sampled Phytophora infestans from different potato producing regions in China,and then analyzed population structure and genetic diversity,including mating type,metalaxyl sensitivity and SSR genotyping.The results are as follows:A total of 213 isolates of Phytophora infestans were sampled from Yunnan,Sichuan,Guizhou,Hubei,Inner Monglia and Heilongjiang province in 2015.All the isolates were used for mating type test,metalaxyl sensitivity test and SSR genotyping.The Phytophora infestans population in Inner Mongolia was A1 mating type,whereas A2 was the dominant mating type in other provinces.Both A1 and A2 existed in Sichuan,Heilongjiang and Guizhou province.The metalaxyl resistant test showed that 15.82%were highly-resistant,72.77%were intermediate-resistant and 1.41%were sensitive to metalaxyl.Over 80.00%were metalaxyl-resistant type(highly-resistant and intermediate-resistant)in each region.All of the isolates from Inner Mongolia showed resistant to metalaxyl,and highly-resistant type accounts for 80.00%.12 SSR markers used in this study and was assigned 4 different labels.Among 213 Phytophora infestans isolates,73 SSR multiplex genotypes(MLG)were detected.Two MLGs,MLG 50 and MLG 71,were the dominant genotypes in northern China.There is not a significant dominant genotype in southern.While,only three genotypes were shared in population sampled from north and south,MLG 20 existing both in Heilongjiang and Hubei,MLG 50 existing both in Heilongjiang and Yunnan,MLG 61 existing in Heilongjiang,Sichuan and Yunnan.Based on SSR data,there was more variance between population in analysis of molecular variance(AMOVA).Population were classified into three group,Group I and Group ? contains these isolates from Hubei and Inner Mongolia,respectively.The isolates form Yunnan,Sichuan and Guizhou were present in Group?.In the first two dimensions of Principal component analysis(PCA)and were,.In analysis of molecular variance(AMOVA)analysis,we find more wariation in the genetic structure of population among different regions,which is consistent with the results of PCA.These data imply close relationship between genetic structure and geographical distribution of population.