Rice blast is one of the most serious diseases in rice (Oryza sativa L.) worldwide. Jin 23B is the maintainer line, a parent for a number of hybrid rice varieties used widely in China. However, Jin 23B is highly susceptible to rice blast. In this study, Pi1, Pi2, and D12 were introgressed to improve the blast resistance of Jin 23B and its derived hybrids, Jinyou 402 and Jinyou 207, by marker-assisted selection (MAS). The improved Jin 23B, which carried single, two, and three genes, were evaluated for their resistance to rice blast using natural inoculation methods in disease nursery of Xianfeng, Hubei, China. The results showed that, the greater the number of genes contained in the improved Jin 23B and hybrids, the higher the resistance to rice blast. Pi1, Pi2, and D12 showed a strong dosage effect on the resistance to blast in the hybrid background during the entire growth duration in the field condition, being very useful for breeding blast-resistant hybrids. The result of examining agronomic traits showed that the improved Jin 23B and its derived hybrid rice were taller than or similar to controls, when there was no disease stress.
稻瘟病是世界范围的最严重水稻病害之一。在中国，金23B作为保持系，是选育众多杂交稻品种时广泛使用的一个亲本，但它非常易受稻瘟病侵染。在我们的研究中，通过标记辅助选择（MAS）的方法，将基因Pi1, Pi2, 和D12 导入到金23B及其衍生的杂交稻金优402和金优207中。然后将改良后的携带这其中1个、2个或者3个基因的金23B植株用自然接种的方法在中国湖北咸丰县的病圃进行稻瘟病抗性的评估。结果表明金23B及其杂交水稻中所包含的抗性基因越多，则其对稻瘟病的抗性越强。在大田条件下，杂交植株内的Pi1, Pi2 和D12基因在植株的整个生育期中显示出了强烈的对稻瘟病抗性的剂量效应，这对于培育抗稻瘟病的杂交水稻是十分有用的信息。农艺性状的检测表明了改良后的金23B及其衍生的杂交水稻植株在没有疾病胁迫的情况下比控制组要高一些或者差不多。