水稻类病斑突变体lmm4的鉴定及其基因定位

Identification and Gene Mapping of a Lesion Mimic Mutant lmm4 in Rice

在EMS诱变的日本晴突变体库中,筛选到一个类病斑突变体。该突变体类病斑出现于分蘖始期,而后慢慢扩散至叶鞘、茎秆,最后至整个植株,属于扩散型类病斑突变体。相比野生型,突变体的lmm4的株高明显降低,有效穗数减少,穗长缩短,结实率、每穗实粒数、千粒重均显著降低。遮光处理实验表明,突变体lmm4类病斑的产生受自然光诱导。突变体lmm4的光合色素含量和净光合速率明显低于野生型。电子显微镜观察发现突变体类病斑部位叶肉细胞中的叶绿体结构发育异常。台盼蓝染色实验表明突变体类病斑部有大量的死亡细胞。二氨基联苯胺染色实验表明类病斑部位有过氧化氢沉积。稻瘟病抗性鉴定结果表明,与野生型相比,突变体lmm4对C7和G1等稻瘟病菌生理小种的抗性明显增强。实时PCR分析证明在突变体lmm4中防卫反应相关基因POC1、PAL、PBZ1、PR1的表达量显著提高。遗传分析表明突变体表型符合单隐性核基因控制的遗传规律。lmm4定位在第5染色体着丝粒附近Ind-4和Ind-6之间大约235kb的区域内。

The lesion mimic mutant lmm4 was identified from an EMS-induced Nipponbare mutant library.Brown lesions were first observed on the tip of lmm4 leaves at the initial tillering stage,and spreaded gradually downward to the whole leaf blade and even the leaf sheath.Compared with the wild type,the chlorophyll and the net photosynthetic rate of lmm4 were significantly reduced.The plant height,panicle length,seed setting rate,grain weight were also decreased significantly.The shading assay showed that the lesions on lmm4 leaves were induced by natural light.The histological staining assay indicated that the lesions on lmm4leaves were caused by programmed cell death and hydrogen peroxide accumulated in lmm4 leaves.The lmm4 displayed higher resistance to blast race C7and G1when compared with the wild type.In addition,pathogenesis-related gene POC1,PAL,PBZ1,PR1 were found to be up-regulated in lmm4.Genetic analysis suggested that the phenotype of lmm4 was controlled by a single recessive nuclear locus.Based a map-based cloning strategy,the lmm4 was narrowed down to a 235kb region between Ind-4and Ind-6near the centromere of chromosome 5.