Improving rice blast resistance and fragrance of rice maintainer through marker-assisted selection

Objective  The acquisition of high quality disease-resistant rice maintainers is the premise of improving the quality and resistance of sterile lines. The molecular marker-assisted selection (MAS) can be used for oriented breeding and accelarating the breeding process of elite rice maintainers.

Method  ‘Hengfeng B’ and ‘Guang 8B’ were used as recurrent parents, and ‘B39’ carrying fragrance gene Badh2and rice blast resistance gene Pita was used as donor parent. The successive backcross breeding and MAS technology was combined to improve the quality and resistance traits of these two maintainer lines.

Result  Through multi-generation backcross breeding, 14 samples of BC₃F₂ improved materials were obtained. The improved single-plant line was tested with the corresponding sterile line, and the sterility grades of the corresponding plot were fully sterile and high sterile. Through quality and resistance identification, most of improved target strains were rated as strong aroma. The resistance to rice blast significantly improved and the disease nursery identification showed that they were resistant or highly resistant to rice blast. Rice quality was characterized by slender rice grains with low amylose content and low chalkiness. Other agronomic and economic characteristics were similar to the recurrent parent. The genetic background recovery rates of most strains were 80% to 90% which met the estimated recovery effect.

Conclusion  MAS shortens the process of trait improving for maintainer lines, helps acquiring improved maintainers with better quality, stronger blast resistance and fragrance, and realizes the oriented genetic improvement of ‘Hengfeng B’ and ‘Guang 8B’, which lays a foundation for further integrated improvement in rice quality and resistance of three-line hybrid rice.