A Study on Correlation between Blast Resistance and Genetic Diversity of Rice Varieties in Yunnan Province

A total of 24 SSR primers were used to analyze the genetic diversity of 160 rice varieties,which were collected from 6 test-sites in Yunnan province.Furthermore,160 rice varieties were mixed inoculated by 8 dominant races of Magnaporthe grisea selected in Yunnan from 2000 to 2006 to analyze their resistance-susceptibility to M.grisea.The results indicated a rich genetic diversity among rice varieties in the target region of Yunnan Province.A total of 324 SSR alleles,with a molecular length ranging from 100 to 500 bp,were tested out of the 160 rice varieties.The mean Shannon index of the population was from 0.347 to 1.719.The cluster analysis revealed a significant genetic variation among the six geographical sites where the rice varieties were collected as the similarity coefficients varied from 0.101 to 0.996,indicating an obvious association between the genetic diversity of the rice varieties and their geographical distribution.The genetic diversity level of six test-sites were YongdeYuanyangShipingBaoshanYuxiShilin.The resistance-susceptibility of rice vatiety differs remarkably: resistance(31 varieties),mid-resistance(38 varieties),mid-susceptibility(83 varieties),and susceptibility(8 varieties).The propotion of resistance rice of different regions were YuanyangBaoshanShipingYongdeYuxi / Shilin.According to the pearson correlation coefficient test between the genetic diversity index and resistance-susceptibility to M.grisea,there were significant negative correlation(P0.01) between rice blast disease class(X) and Shannon index(I),the percentage of polymorphic loci(P) or expected heterozygosity(He).Thus the resistance level of rice variety would increase as genetic diversity rising in Yunnan province.