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Xa 2 5是从体细胞突变体HX 3中鉴定出的水稻抗白叶枯病基因。通过花药培养构建了 0 2 4 2 8(粳稻 )和HX 3(籼稻 )的双单倍体 (DH)群体 ,该群体包含了 12 9个稳定株系 ,以我国长江流域水稻白叶枯病的代表菌株浙173对DH群体进行抗病性鉴定 ,抗病株系数和感病株系数分别为 6 2和 6 7。共选用覆盖水稻 12条染色体的 30 0对SSR引物对 0 2 4 2 8和HX 3进行多态性分析 ,有 74对引物在双亲之间表现差异。利用这些差异引物对DH群体进行连锁分析 ,从而将抗白叶枯病基因Xa 2 5定位到第 4染色体长臂末端的两个SSR标记RM6 74 8和RM 115 3之间 ,连锁距离分别为 9 3cM和 3 0cM。
Xa 2 5 is a rice bacterial leaf blight resistance gene identified from the somatic mutant HX 3. A doubled haploid (DH) population consisting of 0 2 4 2 8 (japonica rice) and HX 3 (indica rice) was constructed by anther culture. This population contains 12 9 stable lines, which are characterized by rice bacterial blight in the Yangtze River valley The representative strain Zhe 173 was used to identify the disease resistance of DH population. The coefficients of resistant and susceptible strains were 62 and 67, respectively. A total of 30 0 pairs of SSR primers covering 12 chromosomes of rice were used to analyze the polymorphism of 0 2 4 2 8 and HX 3, 74 pairs of primers showed differences in parents. Using these differential primers for linkage analysis of DH population, the XB25 gene was mapped to two SSR markers RM6748 and RM1515 at the long arm of chromosome 4 with linkage distances of 9 3cM and 30cM.