论文部分内容阅读
用距离水稻抗白叶枯病基因Xa230.8 cM的EST标记C189,扩增Xa23的近等基因系CBB23的基因组片段(0.8 kb)为探针,筛选水稻明恢63的TAC文库和广陆矮4号的PAC文库,对获得的7个阳性克隆用酶切法和Tail-PCR法进行末端片段分离,获得15个末端片段,用于感病亲本金刚30和抗病亲本CBB23之间的多态性检测,发现7个末端片段在双亲间有多态性,分别为69B、70N、81N、45B、45N、84N和84B。用这些末端片段作RFLP标记,对金刚30/CBB23的F2群体进行检测和连锁分析,结果表明这些标记与Xa23的遗传距离依次为0.4、0.4、0.4、0.5、0.6、0.6和1.1 cM。虽然69B、70N和81N与Xa23的遗传距离均为0.4 cM,但序列比对揭示69B与70N的物理距离为35 kb,与81N为95 kb,69B距Xa23最近。三者与Xa23的遗传距离虽然相同,但物理距离存在很大差异。这些末端片段标记加密了Xa23基因一侧的遗传图谱,并使其遗传距离缩短到0.4 cM,加速了Xa23的定位进程,为Xa23的分离克隆奠定了重要基础。讨论了这种染色体步移方法的适用条件。
The genomic fragment (0.8 kb) of proximal CBB23 amplified from Xa23 was amplified by C189 tagging with rice cotyledons X30 at a site-dependent distance of 30.8 kb and the TAC library of rice Minghui 63 4 of the PAC library, seven positive clones obtained by restriction endonuclease method and Tail-PCR method for the terminal fragment was isolated, 15 end fragments were obtained for the susceptible parent King 30 and the resistant parent CBB23 polymorphism The results of sex testing showed that there were polymorphisms between the two parents in the 7 end fragments, which were 69B, 70N, 81N, 45B, 45N, 84N and 84B, respectively. Using these fragments as RFLP markers, F2 population of diamonds 30 / CBB23 were detected and analyzed by linkage analysis. The results showed that the genetic distances of these markers to Xa23 were 0.4, 0.4, 0.4, 0.5, 0.6, 0.6 and 1.1 cM, respectively. Although the genetic distances of 69B, 70N and 81N to Xa23 were 0.4 cM, the sequence alignment revealed that the physical distance between 69B and 70N was 35 kb, which was 95 kb compared to 81N, and 69B from Xa23. Although the genetic distance between the three and Xa23 is the same, the physical distance is quite different. These terminal fragment marks the genetic map of one side of Xa23 gene and shortened the genetic distance to 0.4 cM, which accelerated the localization of Xa23 and laid an important foundation for the isolation and cloning of Xa23. The applicable conditions of this chromosome walking method are discussed.