水稻黄叶突变体yl的遗传分析与基因定位

Genetic analysis and gene mapping of a yellow leaf mutant yl in rice

[目的]水稻叶片作为重要的光合器官,是作物产量的形成基础。叶色突变体不仅可以作为育种标记,还是研究叶绿体发育和培育高光效水稻品种的先决条件之一。[方法]从籼稻品种‘9311’的^(60)Co-γ射线辐射诱变突变体库中筛选获得了1个水稻黄叶突变体yl。利用yl/‘宁粳4号’杂交的F2群体进行基因定位。[结果]与野生型相比,yl突变体的幼叶表现出明显的黄化,叶绿素a、叶绿素b、类胡萝卜素的含量下降。突变体叶绿体中类囊体片层结构排列松散。与野生型相比,yl突变体的每穗粒数、结实率和千粒质量下降。该性状受1对隐性核基因控制。该基因初步定位于第9染色体长臂上,进一步开发分子标记把定位区间缩小在14.5 kb内,该区域包含3个候选基因。经测序比对分析发现,yl突变体的第3个ORF的第5外显子发生碱基突变(2131CTA→G),从而造成蛋白第233位氨基酸发生改变并导致翻译提前终止,形成了1个包含原有232个氨基酸和16个新形成氨基酸残基的蛋白,该基因与已报道的水稻黄叶基因YLC1是等位基因。[结论]本研究明确了YLC1参与叶绿素的合成,为叶绿体色素合成和叶绿体发育的研究提供了基础。

[ Objectives ] Leaf, a crucial organ for photosyhthesis, provides the basis of crop yield formation. The leaf color mutants can be used not only as a trait marker in breeding, but also as one of the prerequisites in chloroplast development and cultivation of new germplasms with higher photosynthetic efficiency. [ Methods ] A yellow leaf mutant, named as yl, was isolated from the progeny of ^60Co-γ-rays treated indiea eultivar ＇9311＇.The gene was isolated using an F2 mapping population derived from the cross of the yl mutant and＇ Ningjing 4＇. [ Restdts ] The yl mutant exhibited a stable yellow leaf phenotype during the seedling stage. As compared with the wild-type, the content of chlorophyll a, chlorophyll b and carotenoid reduced in yl leaves.The yl mutant showed less grain number per panicle,less seed setting rate and fewer 1 000-grain weight. The yellow leaf phenotype of the yl mutant was caused by a single recessive gene located in a 14.5 kb region on chromosome 9 containing three ORFs. The yl gene had nucleotide changes （2130CTA→G） in the fifth exon of the 3rd ORF, which led to frame shift and early termination in the process of translating protein. The gene was a novel allele of the YLC1 gene. [ Conclusions] We demonstrated that the YLC1 gene is associated with the chlorophyll synthesis, providing a basis for further study on chloroplast pigment synthesis and chloroplast development.