Busungu Constantine, Taura Satoru, Sakagami Jun-Ichi, Ichitani Katsuyuki
United Graduate School of Agricultural Sciences, Kagoshima University , 1-21-24 Korimoto, Kagoshima, Kagoshima 890-0065 , Japan.
Institute of Gene Research, Kagoshima University , 1-21-24 Korimoto, Kagoshima, Kagoshima 890-0065 , Japan.
Breed Sci. 2016 Sep;66(4):636-645. doi: 10.1270/jsbbs.16062. Epub 2016 Aug 3.
Bacterial blight caused by pv. () is a chief factor limiting rice productivity worldwide. XM14, a rice mutant line resistant to , has been obtained by treating IR24, which is susceptible to six Philippine races and six Japanese races, with N-methyl-N-nitrosourea. XM14 showed resistance to six Japanese races. The F population from XM14 × IR24 clearly showed 1 resistant : 3 susceptible segregation, suggesting control of resistance by a recessive gene. The approximate chromosomal location of the resistance gene was determined using 10 plants with shortest lesion length in the F population from XM14 × Koshihikari, which is susceptible to Japanese races. DNA marker-assisted analysis revealed that the gene was located on chromosome 3. IAS16 line carries IR24 genetic background with a Japonica cultivar Asominori segment of chromosome 3, on which the resistance gene locus was thought to be located. The F population from IAS16 × XM14 showed a discrete distribution. Linkage analysis indicated that the gene is located around the centromeric region. The resistance gene in XM14 was a new gene, named . This gene is expected to be useful for resistance breeding programs and for genetic analysis of resistance.
由稻瘟病菌（Magnaporthe oryzae pv. oryzae）引起的稻瘟病是限制全球水稻产量的主要因素。XM14是通过用N-甲基-N-亚硝基脲处理对六个菲律宾稻瘟病菌生理小种和六个日本稻瘟病菌生理小种敏感的IR24而获得的一个抗稻瘟病水稻突变系。XM14对六个日本稻瘟病菌生理小种表现出抗性。XM14×IR24的F群体明显呈现1抗∶3感的分离比例，表明抗性由一个隐性基因控制。利用XM14×越光（对日本稻瘟病菌生理小种敏感）的F群体中病斑长度最短的10株植株确定了抗性基因的大致染色体位置。DNA标记辅助分析表明该基因位于第3染色体上。IAS16株系带有IR24的遗传背景以及第3染色体上粳稻品种秋光的片段，抗性基因位点被认为位于该片段上。IAS16×XM14的F群体呈现离散分布。连锁分析表明该基因位于着丝粒区域附近。XM14中的抗性基因是一个新基因，命名为Pi-xm(t)。该基因有望用于抗性育种计划以及稻瘟病抗性的遗传分析。
