利用分子标记辅助选择改良93-11对白叶枯病和螟虫抗性

93-11是我国生产上应用面积较大的两系恢复系，同时又是红莲型三系杂交水稻恢复系之一，其组配的超级杂交稻两优培九和三系杂交稻红莲优6号，具有优质高产等特性。为了进一步提高其对白叶枯病的抗性、同时增加其对水稻鳞翅目害虫(如稻纵卷叶螟、二化螟和三化螟等)抗性，利用常规回交育种方法和结合分子标记辅助选择将Xa21基因和Bt基因同时导入93-11中，在BC3F，家系中筛选到8个家系含纯合的Xa21基因和Bt基因，其中有两个家系与93-11比较其遗传背景的回复率很高，达到90．59％。在正常的田间条件下，改良的93-11(Bt)、93-11(Xa21)和93-11(Bt／Xa21)与原始的93-11表现出相似的农艺性状，且带有Xa21基因的株系及其杂交种均对白叶枯病显示出很高的抗性。在自然诱发螟虫条件下，带有Bt基因的株系及其杂交种没有受到螟虫危害。这一结果表明，通过分子标记辅助选择将多个基因同时导入某一改良亲本，结合常规育种方法选择，具有快速、良好遗传改良效果。这一遗传改良材料在农艺性状和配合力等方面基本保持了93-11及其杂交组合的主要特征特性，拓宽和增强了其对白叶枯病的抗谱和抗病能力，增加了93-11作为恢复系所配杂交水稻的抗螟虫特性，具有较好的应用前景。

Simultaneously Improvement of Resistance to Bacterial Blight and Stem Borer of 93-11 by Molecular Marker-Assisted Selection

served as an elite restorer line of two-line hybrid, which was widely used in our country's rice production, is also a restorer line of three-line hybrid of the HL type. The super-hybrid rice, Liangyou Pei 9 and Honglianyou 6, which was mated by 93-11, has the characteristics of high yield and good grain quality. In order to enhance its resistance to bacterial blight(BB)and lepidopteran such as leaffolder, striped stem borer and yellow stem borer etc, we intergessed Xa21 and Bt genes into the genetic background of 93-11 by backcross scheme, combining with molecular marker-assisted selection and phenotypic selection. Through three backcross and two self generations, eight families that have homozygous Xa21 and Bt genes were obtained in the BC3F3 families. Two families show higher recovery percentage of 93-11 even up to 90.59%. In the subsequent field evaluation, 93-11(Bt/Xa21)and its hybrid show high resistance to BB and stem borer. The agronomic performance of improved 93-11(Bt), 93-11(Xa21)and 93-11(Bt/Xa21)was very similar to original 93-11 under normal condition. But on the natural stem borer infestation condition, the improved 93-11 contained Bt gene and its hybrid was not damage by stem borer. This result shows: It has a quickly and excellent efficiency to introduce multiple genes simultaneously into a certain improved parent by MAS conjunction with conventional breeding method. The improved line persist the main agronomic trait and combining ability of 93-11, show wide spectrum to Xoo strains and enhanced resistance to BB and stem borer. Thus, this line has good prospect in future practical use.