一个新的水稻叶绿素缺失黄叶突变体遗传分析及其基因定位

Genetic Analysis and Molecular Mapping of a Novel ChlorophyⅡ-deficient Yellow-leaf Mutant in Rice

粳稻品种"嘉花1号"经60Coγ射线辐照后,在其后代中筛选到一个黄叶的突变体(yl6),经过表型分析,发现该突变体幼苗期不论在低温(20℃)还是在高温(32℃)培养条件下,与野生型相比叶色均呈现出淡黄色,表明其为一温度不敏感突变体。光合色素含量测定结果显示,yl6突变体的黄叶突变性状主要是由叶绿素含量下降所导致。电镜结果显示,yl6突变体内叶绿素合成受阻且叶绿体的正常发育受到影响。遗传分析表明,该突变性状受一对隐性核基因(yl6)所控制。利用该突变体与籼稻"培矮64S"杂交产生的F2、F3群体中分离出的608个突变体型单株作为定位群体,结合SSR和CAPS分子标记将yl6基因定位在水稻第6染色体短臂上的CAPS1和RM2353分子标记之间,其物理距离约为271kb,目前该区域内没有发现与水稻叶绿素合成/叶绿体发育相关已知功能基因。本研究结果可为yl6基因的克隆和功能分析奠定了基础。

Through observation of phenotypic trait of the progeny of a japonica rice variety ＂Jiahua 1＂ treated with 60Coγ-radiation, a yellow-leaf mutant （yl6） in rice （Oryza saliva L.） was selected. During the seedling stage, the mutant exhibited light-yellow-leaf phenotype both at the low （20℃） and high temperature （32℃）. These results indicated that yl6 is a themoinsensitive mutant. The light-yellow-leaf phenotype of yl6 was mainly caused by the declining of chlorophyll. Electron microscope observation indicated that the biosynthesis of chloroplastwas hindered and development of chloroplast was affected in yl6 mutant. Genetic analysis showed that the phenotype of yl6 mutant was controlled by a single recessive nuclear gene that named yl6. By using SSR and CAPS molecular markers and 608 individuals of F2 and F3 generation with mutant phenotype derived from the cross of yl6 and the indica variety Peiai 64S, the yl6 was mapped between the molecular markers CAPS1 and RM2353 with 271 kb of physical distance on the short arm of chromosome 6 in rice. There was no geneconferring chlorophyll synthesis or chloroplast development in rice ever being reported in this genomic region. The findings in this study would provide a foundation for the cloning and functional analysis of the ）16 gene in the future.