从粳稻品种'嘉花1号'的60Coγ射线辐照的后代中筛选到一个水稻温敏感失绿突变体tcd51,该突变体在24℃条件以下,幼苗从三叶期开始呈白色失绿,而28℃以上条件下其表型与野生型'嘉花1号'一致,呈正常绿色,表明其幼苗叶色失绿是一种温敏感性状.透射电镜观察表明,突变体tcd51的叶绿体在20℃条件下发育不全,且光合色素含量明显下降,而在32℃条件下叶绿体结构和光合色素含量与野生型基本一致.遗传分析表明,该温敏感失绿突变表型受1对隐性核基因(tcd51)控制.利用该突变体与'培矮64S'杂交构建F2群体以及InDel和SSR分子标记,将tcd51基因定位在水稻第5染色体上的ID5与ID7分子标记之间的 507 kb的区间内,跨越6个BACs,包含26个ORFs.转录表达分析表明,tcd51突变体在20℃低温条件下叶绿素合成、光合作用和叶绿体发育相关基因(PORA,psaA,psbA,rpoB,rpoC)转录水平大幅度下调,而在32℃条件下与野生型无明显差异,说明TCD51可能是一个低温响应且受低温影响的水稻苗期生长的关键基因.本研究为tcd51基因的进一步克隆和功能探索提供了一定的参考.“,”A thermo-sensitive chlorosis mutant tcd51 was selected from the progeny of a japonica rice variety 'Jiahua 1 (WT)' treated with 60Coγ-radiation. The mutant displayed seedling cholosis at the 3-leaf stage below 24℃, but began to turn normal green as the wild-type 'Jiahua 1' above 28℃, indicating that the trait of the seedling leaf color was a thermo-sensitivity. The transmission electron microscope observation showed that the chloroplast in mutant tcd51 was undeveloped under the condition of 20℃, and photosynthetic pigment content decreased obviously, while they became almost the same as WT plants at 32℃. In addition, the genetic analysis indicated that the trait of the thermo-sensitive chlorosis in mutant was controlled by a pair of recessive nuclear gene (tcd51). Using the F2 population from the cross of 'Pei'ai 64S'/tcd51 and InDel and SSR molecular markers, the tcd51 gene was located to the 507 kb between ID5 and ID7 molecular marker on chromosome 5, which spanned six BAC clones and contained 26 ORFs. Additionally, the transcript analysis suggested that those genes associated with chlorophyll synthesis, photosynthesis and chloroplast development (PORA, psaA, psbA, rpoB, rpoC) under 20℃ were significantly down-regulated, but there was no significant difference from WT plants under 32℃, implying that TCD51 gene was likely to be a key gene that was responsive to low temperature and affected the growth of rice seedlings. This research provided a reference for further cloning and functional exploration of tcd51 gene.