Improving Resistance To Rice Blast In Restorer Line JXR-33 By Molecular Marker-Assisted Selection

As one of the most important cereal crops, rice (Oryza sativa L.) plays a key role in food production in the world. But rice yield is often suffered huge losses by the destructive rice blast disease each year. It has proved to be the most effective and economical strategies to alleviate the harm by breeding new varieties with multi-resistances. Currently a large number of blast-resistant genes have been identified; among which Pi-Kh, Pi-1 and Pi-9 are wide-spectrum resistant genes. JXR-33 is an elite restorer line for the two-line way hybrids, but it is susceptible to blast disease. In this paper, three blast disease resistant genes, Pi-Kh, Pi-1 and Pi-9 were introgressed into JXR-33 by means of marker-assisted selection (MAS). The main results are as follows:1. Donor parent M32B with the Pi-Kh, Pi-1 and Pi-9 was crossed with the recipient parent JXR-33 and followed by three times backcross and by MAS, the three genes, Pi-Kh, Pi-1 and Pi-9 were successfully pyramided into JXR-33. And two near-isogenic lines, JXR-135 and JXR-136, were bred, which were very similar with JXR-33 in agronomic traits, but have been greatly improved in resistance to blast disease.2. The results of blast resistance test in greenhouse indicated that, the JXR-135 and JXR-136 were significantly higher than the controllers C101 LAC (Pi-1),75-1-217 (Pi-9), IRBLkh-K3 (Pi-Kh) and JXR-33, and similar with the donor parent M32B in resistant levels. Their hybrids, NongLY3135(HS-3/JXR-135) and NongLY3136(HS-3/JXR-136), were also significantly higher than the hybrid JinLY33(HS-3/JXR-33) in resistant levels tested in the fields.3. JXR-135 and JXR-136 are a little shorter than JXR-33 in plant heights, and very similar in other agronomic traits. Their hybrids NongLY3135 and NongLY3136 increased yield by 6.05%,3.93% than controller JinLY33,19.87%,16.99% than Ⅱ YouMing86 and 6.39%,4.26% than Ⅱ You3301, respectively. It suggested that the two hybrids possessed good productivity. In which the NongLY3135 has been recommended to regional trials in Fujian Province in 2012.