Abstract: Three recombinant inbred lines (RILs) carrying rice blast resistance gene Pi25 from the combination Zhong 156/Gumei 2 were crossed with highyielding restorer lines, 9308 and 311. The seeds were collected and advanced by single seed descent, and six RIL populations at the F6 generation were obtained and used for the study. Based on the previously reported genetic map, four additional SSR markers RM3330, RM564, RM3628 and RM6298 were added to the interval harboring Pi25 on rice chromosome 6. Relied on the marker genotyping of RM3330 and A7, 109 Pi25 homozygous lines were selected from the six RIL populations. Markerassisted selection analysis was carried out on the acquired 109 Pi25 homozygous lines using existing markers linked to fertility restoring genes. As a result, twenty restorer lines resistant to blast were obtained. Studies on fertility restoring ability of the 20 restorer lines concluded that the seedsetting rate of crosses between these restorer lines and cytoplasmic male sterility lines (Zhong 9A and Ⅱ32A) reached a normal level. In addition, three populations were selected to be artificially inoculated with a regionally prevalent isolate 05201 of Magnaporthe grisea to evaluate the accuracy of markerassisted selection. The result manifested that simultaneous selection of the markers flanking the gene on both sides could increase the selection accuracy significantly.

Key words: hybrid rice, blast resistance, markerassisted selection

摘要： 从组合中156/谷梅2号所衍生的重组自交系群体中选择携带抗稻瘟病基因Pi25的3个株系，分别与高产恢复系9308和311配组，通过单粒传法获得的6个F6重组自交系群体用于研究。在Pi25先前定位的遗传图谱上，新增加与该基因紧密连锁的分子标记RM3330和A7，并结合RM3330和A7分子标记辅助选择的结果，共筛选到了109个Pi25基因纯合的株系。用现有的与恢复基因连锁的标记对这109个株系进行二次筛选，最终获得20个Pi25基因和恢复基因均纯合的株系。对育性恢复力鉴定试验表明，选育出的抗病恢复系具有较好的恢复能力，并已应用于育种实践；人工稻瘟病接种试验证实，所用标记不同，分子标记辅助选择的效率差异显著，单个标记辅助选择符合率均不高，而采用目标基因两侧连锁的标记同时进行辅助选择，则可以明显提高分子标记辅助选择符合率。

关键词: 杂交水稻, 抗稻瘟病性, 分子标记辅助选择, 恢复系