Résumé
Oryza longistaminata with strong resistance to biotic and abiotic stress was regarded as an excellent gene pool of wild rice, mining and utilization of favorable genes of O. longistaminata would be important in breeding of O. sativa by broadening its genetic basis. To explore blast resistant genes from O. longistaminata, RD23, an indica cultivar from Thailand, was crossed with an accession of O. longistaminata through embryo rescue, and a set of BC3F7 introgression lines (ILs) had been constructed. The ILs were tested for blast resistance in natural blast nursery, and three desirable ILs that exhibited a high level of resistance to rice blast was obtained. Using a BC4F2 population from a cross of IL-E1454/RD23, a novel dominant blast resistant gene, designated as Pi57(t), was mapped on chromosome 12 of rice flanked by SSR markers RM27892 and RM28093. It was found that Pi57(t) conferred a broad-spectrum resistance to Magnaporthe oryzae isolates collected from Yunnan, and the resistant spectrum distinguished from 5 known blast R genes located on chromosome 12. Our results suggest that the Pi57(t) would be a promising gene for breeding blast-resistant rice in Yunnan, China. (Texte intégral)