水稻白条纹转绿突变体wsl887的鉴定和基因定位

温敏型水稻叶色突变基因的挖掘可以丰富水稻遗传资源,且为研究低温调控叶绿体发育机制的材料。本研究利用⁶⁰Co射线辐射诱变贵州地方稻种资源桥港珍珠米,获得一个新的白条纹转绿突变体wsl887。通过表型鉴定和主要农艺性状调查可知,在自然条件下wsl887叶幼苗呈现白条纹表型,成熟后主要农艺性状与野生型相比均无显著差异;在20℃条件下wsl887叶片呈现白化,光合色素含量显著降低;在25℃条件下wsl887叶片呈现白色条纹,光合色素含量显著升高;在30℃条件下wsl887叶色与野生型无明显差异,光合色素含量无显著差异。透射电镜观察显示,在20℃条件下,wsl887叶肉细胞中无叶绿体或者叶绿体发育畸形;在30℃条件下,wsl887叶绿体数量和形态均恢复正常。qRT-PCR分析表明,wsl887在20℃和30℃条件下,与野生型相比,部分光合色素代谢途径基因、光合作用及线粒体电子传递相关基因的表达水平呈现不同程度的变化。遗传分析表明,wsl887突变体的表型受一对隐性核基因WSL887控制,该基因被定位于2号染色体上的SSR标记RM262和RM5427之间,物理距离为743.6 kb。该白条纹转绿突变体wsl887是一个新的温敏型叶色突变体,在自然条件下其主要农艺性状没有发生显著变化,未对植株产量造成影响,因此在杂交水稻上具有较大的应用价值。在不同温度条件下,由细胞质编码的基因表达量均显著减少,由此推测该突变基因可能与细胞质中叶绿体的发育有关。本研究结果为进一步克隆wsl887突变基因和研究基因功能奠定了一定的理论基础。

Phenotypic Identification and Gene Mapping of Green Revertible White-Stripes Mutant wsl887 in Rice (Oryza sativa L.)

Discovery of thermosensitive rice leaf-color mutant genes can enrich rice genetic resources and providing materials for studying the mechanism of the chloroplast development regulated by low-temperature. In the present study, a new green revertible white-stripe mutant, wsl887, was isolated from Qiao-gang Pearl Rice, a local rice germplasm in Guizhou, by ⁶⁰Co irradiation. Results showed that wsl887 displayed a white-stripe phenotype at seedling stage in the field. However, the main agronomic traits at maturation stage, didn't show significant differences from that of the wild type. When grown at 20℃ and 25℃, wsl887 displayed albino and white-stripe leaves, respectively, with significantly decreased photosynthetic pigment when compared with the wild type. Interestingly, when grown at 30℃, leaf color and photosynthetic pigment content of ws1887 showed no significant difference with those of the wild type. Transmission electron microscopy observation revealed that, wsl887 had no or deformed chloroplasts in mesophyll cells of the albino leaves at 20℃, but had the same number and normal morphology of chloroplasts at 30℃. The qRT-PCR results indicated that genes related to photosynthetic pigment metabolic pathway, photosynthesis and mitochondrial electron transport were differentially expressed in wsl887 at different temperature (20℃ and 30℃), when compared with those in the wild type. Genetic analysis demonstrated that the phenotype of wsl887 was controlled by a single recessive nuclear gene. Finally, WSL887 was located between SSR markers RM262 and RM5427 on chromosome 2, with a physical distance of 743.6 kb. By analyzing the genes located in the candidate region, wsl887 is a new thermosensitive leaf color mutant, which has great application value in hybrid rice due to its mutation without compromising the yield of the plant and the main agronomic traits under natural conditions. Under different temperature conditions, the expression of the genes in cytoplasm was significantly reduced in wsl887. Taken together, we hypothesized that the WSL887 could be the key gene responsible for the development of chloroplast in cytoplasm. This study laid a solid foundation for further cloning the wsl887 mutant gene and studying the gene function.