Pathogenicity and population structure analysis of Pyricularia oryzae in different districts of Jiangsu province, China

Abstract

AbstractRice blast caused by Pyricularia oryzae is one of the most destructive rice diseases worldwide. In this study, 224 isolates were isolated from neck blast samples from nine districts in Jiangsu. We analysed the resistance frequency of 24 resistance (R) genes using 32 monogenic rice lines from the International Rice Research Institute (IRRI), including Pii, Pik‐h, Pi5, Piz‐5, and Piz, which exhibit high resistance frequencies. PAC (pathogenicity association coefficients) and VAC (virulence association coefficients) analyses identified three combinations of R genes, Piz/Pii, Piz/Piz‐5, and Piz/Pi5, as being suitable for use in Jiangsu. Mating‐type analysis of P. oryzae isolates indicated that sexual reproduction occurred less frequently in northern Jiangsu than in other areas, which may affect genetic diversity and dissemination. Pot2‐TIR analysis indicated that the genetic diversity of P. oryzae in Xuzhou was mainly due to the insertion of transposable elements, while that of Nanjing was due to both the insertion of transposable elements and sexual recombination. Therefore, some R genes or gene combinations were suitable for resistance breeding in Jiangsu, and repetitive‐PCR (rep‐PCR) is a cost‐effective tool for genetically differentiating distinct cultivar‐specific populations or lineages with well‐defined virulence patterns, because of the close correspondence between rep‐PCR based clusters and pathotypes of inbred lines.