DEVELOPMENT OF EXPRESSED SEQUENCE TAG-DRIVED SIMPLE SEQUENCE REPEAT MARKERS AND DIVERSITY ANALYSIS OF PHYTOPHTHORA CAPSICI IN

Phytophthora capsici is a highly dynamic and destructive pathogen of vegetable and great interests on the genetic structure of P. capsici have grown in the world. However, there is little genetic information about P. capsici based on the EST-SSR markers. In this study, 193 SSR markers were developed and 33 selected markers were successfully detected and they were polymorphic with the number of alleles per locus ranging from 2 to 7. 4 SSR markers were further selected for genetic diversity analysis and Nei’s genetic diversity values of 15 populations ranged from 0.38 to 0.66, with an average of 0.53. The higher polymorphism and greater transport ability of these markers among P. capsici species were proved by the expected heterozygosity (He =0.64) and Shannon’s index of diversity (I =1.14), indicating that they maintained a substantial level of genetic diversity. Additionally, the genetic differentiation among the 4 markers (Fst =0.15) was moderate and the gene flow among groups was consequent (Nm =1.69). Clustering analyses revealed that 15 populations are made of two differentiated genetic clusters and are similar regarding genetic diversity composition. Our results suggest that there are considerable evolutionary potential of P. capsici in China and useful management strategies should be adapt to it