水稻抗白叶枯病基因Xa-25的分子定位

Xa-25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02428(粳稻)和HX-3(籼稻)的双单倍体(DH)群体，该群体包含了129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62和67。共选用覆盖水稻12条染色体的300对SSR引物对02428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-25定位到第4染色体长臂末端的两个SSR标记RM6748和RM1153之间，连锁距离分别为9．3cM和3．0cM。

Molecular Mapping of a Bacterial Blight Resistance Gene Xa-25 in Rice

Xa-25 was a bacterial blight resistance gene identified in a somaclonal mutant HX-3.A doubled-haploid (DH) population including 129 stable lines was derived from anther culture of a typical japanica 02428 and a typical indica HX-3 cross.The bacterial blight strain Zhe173,a typical bacterial blight strain in Yangtze River valley,was used to test the resistance or susceptible of the DH population lines ,and the results showed that the resistance lines and susceptible lines were 62 and 67,respectively.A total of 300 SSR primer pairs covering 12 rice chromosomes were used for polymorphism survey of 02428 and HX-3 .Among these primers,74 showed polymorphism between the parents.Using these polymorphic SSR markers,bulked segregant analysis was conducted on the DH population.As the result,Xa-25 was located at the terminal region of the long arm of chromosome 4 between the two SSR markers RM6748 and RM1153,the map distance between Xa-25 and the two SSR markers was 9.3 cM and 3.0 cM,respectively.