水稻类病变突变体lms1的表型鉴定与抗病分子机制分析

Phenotypic identification and disease resistance mechanism analysis of rice lesion mutant lms1

类病变突变体是研究植物细胞死亡和抗病分子机制的重要遗传材料。通过辐射诱变粳稻品种武运粳7号,获得一个少见的抗病性下降的类病变突变体lms1(lesion mimic and disease susceptible mutant 1)。与野生型相比,该突变体叶片自发出现红褐色斑点,其株高、穗长、每穗粒数以及单株产量降低,但千粒重增加;对水稻白叶枯病的抗性显著下降,组织染色表明突变体的叶片中存在明显的细胞死亡以及活性氧的过量积累。遗传分析表明,lms1突变体的表型受单隐性核基因控制,利用图位克隆技术将lms1基因精细定位于水稻9号染色体Indel7和Indel8两个分子标记间,物理距离为62 kb。定位区间内候选基因的PCR扩增测序结果表明,其中一个编码泛素羧基末端水解酶的OsLMP1(Lesion Mimic Phenotype 1)基因第1个外显子中插入了一段长度为654 bp的序列,导致其蛋白翻译提前终止。利用蛋白组学技术分析了lms1突变体与野生型对照的蛋白积累水平,共鉴定到19个差异蛋白(7个上调、12个下调),主要参与氧化还原、叶绿素合成、光合作用等代谢途径。上述结果为进一步研究OsLMP1基因的功能及其调控细胞程序性死亡与抗病性的分子机制提供借鉴。

Lesion mimic mutants are important genetic materials for studying molecular mechanisms of plant cell death and disease resistance.Through radiation mutagenesis of a japonica rice cultivar‘Wuyunjing 7’,a rare lesion mimic and disease-susceptible mutant lms1 was obtained.Compared to the wild type,the leaves of this mutant spontaneously appeared reddish-brown spots,and its plant height,panicle length,number of grains per panicle,and yield per plant decreased,but the weight of 1000-grain increased.In addition,the resistance of lms1 to rice bacterial blight decreased significantly,and tissue staining showed significant cell death and excessive accumulation of reactive oxygen species in the mutant leaves.Genetic analysis showed that the phenotype of the lms1 mutant was controlled by a single recessive nuclear gene,and the lms1 gene was finely located between two molecular markers,Indel7 and Indel8,on chromosome 9 of rice with a physical distance of 62 kb.PCR amplification and sequencing of candidate genes in the localization interval showed that a 654 bp sequence was inserted into the first exon of the OsLMP1(Lesion Mimic Phenotype 1)gene,which encodes a ubiquitin carboxyl-terminal hydrolase,resulting in premature termination of protein translation.The protein compositions of lms1 mutants and WT controls were analyzed by a proteomics technology,which identified a total of 19 differentially accumulated proteins(7 upregulated and 12 down-regulated),mainly involved in redox,chlorophyll synthesis,photosynthesis,and other metabolic pathways.The above results provide a reference for further research on the function of the OsLMP1 gene and its molecular mechanism of regulating programmed cell death and disease resistance.