Morphological and molecular characterization of rice blast resistant advanced lines
摘要
The fungus Magnaporthe oryzae is the causal agent of rice blast disease, posing a significant threat to global rice production. To develop durable and broad-spectrum resistance against this disease, we employed marker-assisted backcrossing to introgression of two major blast-resistant genes, Pb1 and Pi9. These genes were successfully introduced into the genetic background of a highly susceptible rice breeding line, BRRI dhan48, using a marker-assisted backcross breeding approach. Through comprehensive screening of 129 BC3F6 individuals, we identified 30 superior fixed advanced lines (ALs) carrying both target resistance genes. Bioassay evaluations of these ALs revealed exceptional resistance to the blast pathogen, with disease ratings ranging from 0 to 3 significantly lower than that of the recipient parent, which exhibited disease ratings of 7–9. In addition to enhanced disease resistance, the ALs also demonstrated superior agronomic performance compared to the recipient parent and other check varieties. Notably, several lines, including G19, G5, G3, G24, and G28 exhibited significantly higher grain yields (ranging from 8.35 to 8.62 tons ha−1) than the recipient parent (7.28 tons ha−1). Similar improvements were observed across other key agronomic traits. Overall, marker-assisted backcrossing proved to be an effective strategy for the precise identification and introgression of blast resistance genes, facilitating the development of high-yielding, blast-resistant rice lines suitable for sustainable cultivation.