Lee Sang-Kyu, Song Min-Young, Seo Young-Su, Kim Hye-Kyung, Ko Seho, Cao Pei-Jian, Suh Jung-Pil, Yi Gihwan, Roh Jae-Hwan, Lee Sichul, An Gynheung, Hahn Tae-Ryong, Wang Guo-Liang, Ronald Pamela, Jeon Jong-Seong
Plant Metabolism Research Center and Graduate School of Biotechnology, Kyung Hee University, Yongin, Korea.
Genetics. 2009 Apr;181(4):1627-38. doi: 10.1534/genetics.108.099226. Epub 2009 Jan 19.
Rice blast, caused by the fungus Magnaporthe oryzae, is one of the most devastating diseases of rice. To understand the molecular basis of Pi5-mediated resistance to M. oryzae, we cloned the resistance (R) gene at this locus using a map-based cloning strategy. Genetic and phenotypic analyses of 2014 F2 progeny from a mapping population derived from a cross between IR50, a susceptible rice cultivar, and the RIL260 line carrying Pi5 enabled us to narrow down the Pi5 locus to a 130-kb interval. Sequence analysis of this genomic region identified two candidate genes, Pi5-1 and Pi5-2, which encode proteins carrying three motifs characteristic of R genes: an N-terminal coiled-coil (CC) motif, a nucleotide-binding (NB) domain, and a leucine-rich repeat (LRR) motif. In genetic transformation experiments of a susceptible rice cultivar, neither the Pi5-1 nor the Pi5-2 gene was found to confer resistance to M. oryzae. In contrast, transgenic rice plants expressing both of these genes, generated by crossing transgenic lines carrying each gene individually, conferred Pi5-mediated resistance to M. oryzae. Gene expression analysis revealed that Pi5-1 transcripts accumulate after pathogen challenge, whereas the Pi5-2 gene is constitutively expressed. These results indicate that the presence of these two genes is required for rice Pi5-mediated resistance to M. oryzae.
由稻瘟病菌（Magnaporthe oryzae）引起的稻瘟病是水稻最具毁灭性的病害之一。为了解Pi5介导的对稻瘟病菌抗性的分子基础，我们采用图位克隆策略克隆了该位点的抗性（R）基因。对感病水稻品种IR50与携带Pi5的RIL260品系杂交产生的定位群体的2014个F2后代进行遗传和表型分析，使我们能够将Pi5位点缩小到一个130 kb的区间。对该基因组区域的序列分析鉴定出两个候选基因Pi5-1和Pi5-2，它们编码的蛋白质带有R基因特有的三个基序：一个N端卷曲螺旋（CC）基序、一个核苷酸结合（NB）结构域和一个富含亮氨酸重复序列（LRR）基序。在感病水稻品种的遗传转化实验中，未发现Pi5-1基因和Pi5-2基因单独赋予对稻瘟病菌的抗性。相反，通过将分别携带每个基因的转基因株系杂交产生的同时表达这两个基因的转基因水稻植株，赋予了Pi5介导的对稻瘟病菌的抗性。基因表达分析表明，Pi5-1转录本在病原体侵染后积累，而Pi5-2基因组成型表达。这些结果表明，这两个基因的存在是水稻Pi5介导的对稻瘟病菌抗性所必需的。
