水稻温敏型叶片白化突变体tsa1的表型鉴定和基因定位

一个由甲磺酸乙酯(EMS)诱变宁粳36水稻品种获得的温敏型叶片白化突变体tsa1在低温条件下(20~24°C)表现叶片白化，但在较高温度下(28~32°C)叶色与野生型无显著差异。突变体白化叶片中叶绿素a和类胡萝卜素含量与野生型相比显著下降。显微观察发现突变体白化组织中正常叶绿体数量稀少，包含大量小型的异常叶绿体，进一步用透射电镜观察发现异常叶绿体中无发育完整的类囊体片层结构，表明该突变体中叶绿体发育存在严重缺陷。遗传分析表明该突变性状受单个隐性核基因控制。利用tsa1与南京11杂交所得的F₂群体中的368个隐性极端个体，将该突变基因定位于第5染色体长臂163 kb的范围内。本研究为该基因的图位克隆及功能解析奠定了基础。

Phenotypic Characterization and Gene Mapping of a Thermo-sensitive AlbinoLeaf Mutant tsa1 in Rice

A thermo-sensitive albino leaf mutant tsa1 was obtained from Ningjing36 induced by Ethyl methane sulfonate (EMS). The mutant developed albinotic leaves under low temperature(20-24°C), and the color of mutant leaves was comparable with the wild-type under high temperature (28-32°C). Compared with wild type, the chlorophyll a and carotene contents of mutant albinotic leaves obviously decreased under low temperature condition. With microscopeobservation, the quantity of normal chloroplast significantly decreased, besides, there were a large number of small abnormal chloroplasts in albinotic leaves. The abnormal chloroplast in albinotic tissue of mutant had no obvious thylakoid stack under transmission electron microscopy. These results indicate that tsa1 mutant has defect on chloroplast development under low temperature. Genetic analysis indicated that the mutant phenotype was controlled by a single recessive nuclear gene. Genetic mapping of the mutant gene was conducted using 368 recessive individuals from F₂ population of tsa1/Nanjing 11, the target gene was finally located in a 163 kb region on the chromosome 5. This study provides a basis for map-based cloning and functional analysis of the target gene.