利用分子标记辅助选择聚合Pi-1和Pi-2基因改良两系不育系稻瘟病抗性

以含广谱稻瘟病抗性基因Pi-1和Pi-2的BL122为供体, 温敏核不育系GD-7S为受体, 通过杂交、回交和自交并结合分子标记辅助选择, 将Pi-1、Pi-2基因导入温敏核不育系GD-7S中, 获得5个携带两个抗性基因的纯合改良不育株系。利用34个广东代表性稻瘟病菌株接种鉴定, 5个改良株系的抗性频率为94.12%~97.06%, 而对照GD-7S抗性频率仅为17.65%; 自然病圃诱发鉴定5个改良株系的叶瘟和穗颈瘟均为0级, 表现高抗。经自然条件和人工气候箱育性鉴定, 改良株系与对照均为无或少花粉败育类型, 自交结实率为0, 说明不育起点温度与对照基本一致。统计分析表明, 除剑叶长和每株穗数外, 改良株系与对照在其他农艺性状方面均无显著差异。与恢复系L38杂交, 改良株系的杂种F1与对照的F1大多农艺性状无显著差异, 说明改良株系基本保持了GD-7S的农艺性状和配合力。

Improvement of Rice Blast Resistance in TGMS Line by Pyramiding of Pi-1 and Pi-2 through Molecular Marker-Assisted Selection

Blast is one of the most serious diseases of rice worldwide, which usually leads to a sharp decline in rice production and even results in no yield. Breeding blast-resistant varieties is one of the most effective and economical ways to control the disease. In this study, the BL122 contained two blast resistance genes Pi-1 and Pi-2 was used as gene donor to be crossed and then backcrossed with the TGMS line GD-7S. Five improved TGMS lines with Pi-1 and Pi-2 homozygous genotype were successfully developed through molecular marker-assisted selection. The resistance frequency of the improved TGMS lines ranged from 94.12% to 97.06%, much higher than that of the check GD-7S, which was only 17.65%, by artificially inoculating 34 representa-tive blast isolates collected in Guangdong Province. The improved TGMS lines also displayed high resistance to leaf and neck blast in the epidemic areas. The critical temperature of fertility transformation for the improved TGMS lines from fertile to sterile was preliminarily identified in the phytotron with the regime of 12.5 h/23℃ and natural conditions. The results showed that the critical temperature point for the improved TGMS lines was likely consistent with that of the check GD-7S. The statistical analysis showed there was no significant difference in the agronomic traits between improved TGMS lines and GD-7S except the flag leaf length and number of panicles per plant. Moreover, there was also no significant difference in most of the agronomic traits be-tween the F1s derived from the crosses of the same restorer line L38 with both the check GD-7S and the improved TGMS lines, respectively. All these indicated that the improved TGMS lines retained almost the same agronomic traits and combining ability as the check.