一个新水稻温敏感叶色突变体的遗传分析及其基因分子定位

在粳稻品种嘉花1号(Oryza sativa L. ssp. japonica ‘Jiahua No.1’)种子经⁶⁰Co γ射线辐照处理的后代中, 发现了1个低温敏感叶色突变体mr21。在较低温度(<25.0°C)条件下, 该突变体幼苗叶色呈黄色; 随着温度逐渐升高, 叶色由黄转绿,其临界温度约为27.5°C; 在低温条件下, 突变体幼苗总叶绿素含量以及叶绿素a、b的含量均较野生型嘉花1号明显下降, 表明该突变体的叶色性状具有明显的温敏感性。遗传分析表明, 该突变体叶色性状受1对隐性核基因控制, 暂将该突变基因命名为thermo-sensitive leaf-color 1(tsl-1)。以该突变体与籼稻9311(Oryza sativa L. ssp. indica ‘9311’)杂交的F₂代分离群体作为定位群体, 利用SSR分子标记将tsl-1基因初步定位在水稻(Oryza sativa)第1号染色体短臂上的MM1799与RM8132分子标记之间, 其遗传距离分别为2.4 cM和3.0 cM; 然后, 进一步利用扩大F₂代群体及新发展的分子标记将tsl-1基因定位在分子标记InDel2与InDel4之间的198 kb内。研究结果为今后对该基因的克隆和功能分析奠定了基础。

Genetic Analysis and Molecular Mapping of a New Thermosensitive Leaf-color Mutant in Oryza sativa

A thermo-sensitive leaf-color mutant, mr21, was discovered in progeny of a rice japonica variety, Jiahua No.1, treated by ⁶⁰Co γ-radiation. Under low temperatures (<25.0°C), the mutant’s seedling leaf color was yellow and turned green with an increase in temperature; the critical temperature for leaf-color alteration was about 27.5°C. As well, the contents of total chlorophyll and chlorophyll a and b in mr21 mutant were decreased compared with the wild-type at low temperatures, which showed that the character of leaf color was sensitive to temperature. Genetic analysis revealed that leaf color was controlled by a single recessive nuclear gene, tentatively designated thermo-sensitive leaf-color 1 (tsl-1). Using the F₂ population derived from the cross 9311×mr21 and simple sequence repeat markers, we preliminarily mapped the tsl-1 gene between MM1799 and RM8132 on the short arm of chromosome 1, with a genetic distance of 2.4 and 3.0 cM, respectively. With further development of new molecule markers and a larger F₂ mapping population, the tsl-1 gene was located between InDel 2 and InDel 4 molecular markers with the physical distance of 198 kb. The results will be useful for cloning and functional analysis of the tsl-1 gene.