Abstract

Late blight, caused by Phytophthora infestans is the most important disease of potato (Solanum tuberosum). This study reveals the genetic diversity of P. infestanspopulation in north China. A total of 134 strains of P. infestans were isolated fromdifferent agricultural fields in Hebei, Liaoning, Jinlin and Heilongjiang Provinces in north China. The genetic variation among these strains were analyzed using 15 ‘simple-sequence repeat’ (SSR) markers. The results show that forty different SSR genotypes and an average of 3.8 (range 2 to 9) alleles per locus were found. Low genetic diversity (Shannon’s diversity index = 0.26) was found among these 134strains from four provinces, revealing the presence of clonal populations of the pathogen in this region. The average heterozygosity was 0.162, indicating the low level of genetic variations of P. infestans populations. There was no correlation between population genetic diversity of P. infestans and geographical origin. These results provided a foundation for making integrated control measures in the future.

Key words: Phytophthora infestans, population genetics, simple-sequence repeat (SSR), potato late blight