Study on improving the resistance of indica thermo-sensitive genic male sterile (TGMS) line by using the broad-spectrum blast resistance gene Pi-ja

At present, it is one of the common methods to seek and utilize the broad-spectrum resistance genes to improve the resistance of breeding parents to rice blast. In this study, a japonica rice line 7001S containing a broad-spectrum Pi-ja gene resistant to rice blast was used as a female parent to hybridize with five indica thermo-sensitive genic male sterile (TGMS) lines, Guangmo S, Xiner S, WA918S, W226S and W869S, respectively, using SSR marker RM27322 to identify Pi-ja genotypes, five indica TGMS lines containing a broad spectrum Pi-ja resistance gene to rice blast were established. Furthermore, the five indica TGMS lines with a broad-spectrum Pi-ja resistance gene were used to cross with restorer lines R2877, R900 and PR6547, the correlation between rice blast at seedling stage and panicle stage and the increase of plot yield were studied. The results showed that the resistance of TGMS lines and their combinations with and without Pi-ja gene were significantly different. Pi-ja gene could significantly enhance the resistance of TGMS lines to rice blast at seedling stage and panicle stage. Further plot yield tests showed that for combinations with or without Pi-ja gene, the correlation between panicle blast resistance variation and plot yield (r = 0.436, P = 0.157) was significantly higher than that between seedling blast resistance variation and plot yield (r = 0.130, p = 0.687). This study provides a technical basis for the breeding of rice varieties with broad-spectrum resistance to rice blast by molecular marker-assisted selection.