水稻新黄绿叶基因YGL9的分子定位

叶色突变体是研究高等植物光合作用、叶绿素代谢途径、叶绿体结构与功能分子机制的理想材料。本研究从EMS(ethyl methane sulfonate)处理的缙恢10号(Oryza sativa L.ssp.indica)诱变群体中发现了一个苗期呈现黄绿色、抽穗期渐变为淡绿色的叶色突变体,命名为yellow green leaf 9(ygl9)。与野生型相比,ygl9苗期和分蘖期光合色素极显著降低,抽穗期光合色素显著降低,气孔长度、气孔导度和蒸腾速率极显著增加,净光合速率无明显变化。透射电镜观察表明,ygl9的嗜锇小体增多、基粒模糊、基质片层减少且疏松,但叶绿体结构基本完整。遗传分析显示该突变性状受1对隐性核基因调控。利用西农1A/ygl9 F2群体中的759株隐性单株,最终将YGL9定位在第3染色体短臂SSR标记S03-1和In Del标记Ind03-19之间,遗传距离分别为0.13 c M和0.07 c M,物理距离为63 kb。本研究为YGL9基因的克隆和功能分析奠定了基础。

Molecular Mapping of a New Yellow Green Leaf Gene YGL9 in Rice (Oryza sativa L.)

Leaf color mutants are ideal materials in illuminating molecular mechanism of photosynthesis, chlorophyll metabolic pathway and chloroplast development. A novel mutant named yellow green leaf 9 (ygl9) was isolated from the progeny of ethyl methane sulfonate (EMS) treated Jinhui10 (Oryza sativa L. ssp. indica) and displayed yellow-green leaves at the seedling stage while light green at the heading stage. Compared with those of the wild type, the photosynthetic pigments of the ygl9 mutant reduced very significantly before the tillering stages and significantly in the heading stage. However, there was no obvious changing for net photosynthetic rate between the wild type and the mutant. The characteristics of stomata length, stomatal conductance and transpiration rate increased significantly in the ygl9. The observation by transmission electron microscope showed that the ygl9 mutant contained comparable chloroplasts with more osmiophilic granules, fuzzy grana and fewer/looser stroma lamella to the wild type. Genetic analysis suggested that the mutational trait was controlled by a single recessive gene. Using 759 mutational individuals from the F₂ generation of Xinong 1A/ygl9, the YGL9 locus was finally mapped on the short arm of chromosome 3 between SSR marker S03-1 and InDel marker Ind03-19 with genetic distances of 0.13 cM and 0.07 cM respectively, and the physical distance was only 63 kb. These results provided a foundation for map-based cloning and functional analysis of YGL9 gene.