水稻抗白叶枯病新基因的初步定位

Molecular Mapping of a New Gene for Resistance to Rice Bacterial Blight

【目的】通过与目前国际上已报道的抗白叶枯病基因进行分析比较,推测水稻抗源C4059含有1个新的抗白叶枯病基因,暂命名为Xa36(t)。将水稻抗源C4059的白叶枯病抗性转育到IR24遗传背景下,培育近等基因系并借助分子标记将其抗白叶枯病基因进行定位。【方法】以IR24/C4059的1个F3分离群体为材料,采用分离集团分析法,借助SSR、EST标记对Xa36(t)进行分子标记定位。【结果】找到13个与Xa36(t)连锁的标记,最近的4个标记RM2136、RM7443、RM1233和RM224与目标基因间的遗传距离分别为3.2、3.8、1.9和1.3cM。其中标记RM2136和RM7443位于染色体近端粒一侧,标记RM1233和RM224位于目标基因的另一侧。【结论】通过分子标记检测,将基因Xa36(t)定位于水稻第11染色体长臂末端附近。

【Objective】 Comparison of resistance spectrums with known BB resistance genes and genetic analysis revealed that the rice germplasm C4059 harbored a new BB resistance gene, designated tentatively as Xa36 （t）. Molecular mapping of Xa36 （t） gene and breeding of its near-isogenic line were made by constructing populations with a susceptible indica variety IR24 as recurrent parent.【Method】 A F3 population was used for molecular mapping of Xa36 （t）. Bulked Segregant Analysis （BSA） was adopted to survey SSR and EST molecular markers. 【Result】 Thirteen markers on rice chromosome 11 displayed polymorphism between the S-pool and R-pool. The four molecular markers, RM2136, RM7443, RM1233, and RM224, were the nearest markers to Xa36 （t）. Linkage analysis revealed that RM2136 and RM7443 were located near the telomere of the chromosome, with genetic distances of 3.2 and 3.8 cM to the resistance gene, respectively, while RM1233 and RM224 were located on the other side of Xa36 （t）, with genetic distances of 1.9 and 1.3 cM, respectively. 【Conclusion】 By analyzing the F3 populations, the gene Xa36 （t） was mapped within a length of 4.5 cM on the long arm of rice chromosome 11.