中文摘要：

广谱抗病基因的利用是控制稻瘟病最有效和最经济的方法。来源于华南的地方稻种暹罗占对稻瘟病菌表现出广谱抗性,以普感品种丽江新团黑谷为轮回亲本选育的暹罗占近等基因系NIL-XLZ对测试的44个不同来源稻瘟病菌的抗性频率为84.4%,其抗谱优于广谱抗瘟基因Pi2、Piz,与抗瘟基因Pi9和Pi50相近。为进一步了解暹罗占抗稻瘟病的遗传基础,以感病品种广恢290为母本、暹罗占为父本,构建了广恢290/暹罗占的F2遗传分离群体。选取致病谱较广的稻瘟病菌代表菌株GD08-T19对来源于广恢290/暹罗占的F1与F2个体进行了抗病遗传分析,结果显示F1个体全表现抗病,1760个F2个体的抗感分离比率为4.06∶1,表明暹罗占至少含有一个显性的抗稻瘟病基因。利用分布于Pi2、Pi1、Pita座位附近的44对SSR引物,对构建的抗/感基因池及遗传分离个体进行了分析,将暹罗占含有的一个抗瘟基因定位于水稻第6染色体Pi2/Pi9/Pi50基因家族区域247 kb的范围内。抗菌谱分析、基因特异性分子标记检测及测序分析结果表明：暹罗占含有广谱抗瘟基因Pi50。本研究结果为暹罗占在水稻抗病育种上的应用提供了重要依据。

英文摘要：

The deployment of broad-spectrum resistance genes is the most effective and economic approach for controlling rice blast. The landrace Xianluozhan from South China displayed a broad-spectrum resistance against rice blast fungus. The resistant spectrum of the near isogenic line NIL-XLZ,derived from the Xianluozhan with the blast susceptible cultivar Lijiangxintuanheigu as a recurrent parent,is higher than that of the near isogenic lines of Pi2 and Piz and similar to that of Pi9 and Pi50. To identify the rice blast resistance gene（s） of Xianluozhan,we constructed an F2 population derived from Guanghui 290（as a female parent） and Xianluozhan（as a male parent） for genetic analysis. The blast isolate GD08-T19 which had a broad virulence to rice cultivars from South China was used to inoculate the F1 and 1760 F2 individuals derived from the cross between Guanghui 290 and Xianluozhan.The genetic assay indicated that Xianluozhan carried a dominant blast resistance gene,since all of the F1 plants showed resistant and the segregation of resistant and susceptible progenies tend to fit a 3R： 1S ratio in the F2 population. Based on the bulked segregant analysis（BSA） and recessive class analysis（RCA） with 44 microsatellite markers distributed around the loci of Pi2,Pi1 and Pita,the resistance gene had been mapped in a 247 kb region of Pi2/Pi9/Pi50 family on chromosome 6. The results of resistance spectrum analysis,gene specific markers detection andgene sequence comparison showed that Xianluozhan carried a broad spectrum blast resistance gene Pi50. This study provides useful information for the application of Xianluozhan in rice breeding.