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60Coγ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-color1（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2.4cM和3.0cM;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198kb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.