普通野生稻稻瘟病广谱抗性基因Pi-gx（t）的遗传分析和定位

【目的】探明来源于广西普通野生稻的稻瘟病抗源RB221与部分已知抗病基因水稻品种抗谱的异同，其抗性基因的遗传模式及在染色体上所处的位点，确定其抗病基因是否为新的抗病基因。【方法】采用从广西不同稻作区收集的8个稻瘟病菌系对抗源RB221和11个已知抗病基因的水稻品种进行抗谱测定，并对RB221抗病基因进行等位性分析、经典遗传分析及分子标记定位。【结果】抗源RB221的抗谱与11个已知抗病基因的水稻品种有差异，其对8个菌系均表现出抗病反应，在所有参试品种中抗谱最广。等位性测定结果表明，抗源RB221所携抗病基因与已知抗病基因品种所携带的Pi-3、Pi-7（t）、Pi-ta、Pi-K、Pi-b是不等位。经典遗传分析结果显示，抗源RB221对03-35E菌系的抗性受1对显性基因控制。SSR标记定位结果表明，RB221抗病基因定位于第2染色体的SSR标记RM240与RM1092之间，与RM240的遗传距离为1.3 cM，与RM1092的遗传距离为2.2 cM。【结论】抗源RB221的抗性基因Pi-gx（t）为新发现的抗病基因，位于第2染色体上，与第2染色体上已定位的抗性基因处于不同基因位点上。

Genetic analysis and molecular mapping of a rice blast resistance gene Pi-gx(t) derived from common wild rice

【Objective】The present study was conducted to explore the resistance difference between a novel rice blast resistant germplasm RB221 derived from common wild rice and some rice varieties with known blast resistant gene. The genetic analysis and molecular mapping of this rice blast resistant gene was also carefully examined in order to determine whether the gene was a new rice blast resistant gene or not. 【Method】Eight rice blast isolations derived from all rice growth regions of Guangxi were used to examine the resistant spectrum of RB221 and 11 NILs rice with known resistant gene， and the allelism， classic inheritance， and molecular mapping of this resistant gene were analyzed. 【Result】The research results indicated that the resistant spectrums of RB221 were different from the 11 NILs with known resistant gene. RB221 was tested with the broadest resistance spectrum to all 8 blast isolations. The result of allelism examination indicated that the resistant locus of RB221 was different from the loci of Pi-3， Pi-7（t）， Pi-ta， Pi-K， and Pi-b. Genetic analysis showed that the resistance of RB221 to blast isolation 03-35E was controlled by a pair dominant gene. The gene was mapped onto chromosome 2 by the method of constructing linkage map using microsatellite markers. The gene was located between the two SSR markers RM240 and RM1092 with distances of 1.3 cm and 2.2 cm respectively from the two markers. 【Conclusion】The resistance gene of RB221， named Pi-gx（t）， was a newly discovered resistance gene mapped onto chromosome 2； its gene loci were different from those known rice blast genes that have been already mapped.