拟南芥叶绿体分裂突变体pd137的基因鉴定与分析

Genetic Mapping and Analysis of a Chloroplast Division Mutant pd137 in Arabidopsis thaliana

pd137是经甲基磺酸乙脂(ethyl methane sulphonate,EMS)诱变并通过筛选得到的一个拟南芥叶绿体分裂突变体。该突变体的叶绿体表型与野生型相比有很大差异:叶绿体面积显著增大,细胞中叶绿体数量明显减少。遗传分析显示pd137的突变表型受隐性单基因控制。本研究通过遗传作图将该突变基因粗定位于拟南芥2号染色体的分子标记CH2-13.70和CH2-16.0区间内。该区间内已知的与叶绿体分裂相关的基因只有FtsZ2-1。对FtsZ2-1基因的测序结果显示pd137突变体的FtsZ2-1基因第505位碱基发生了无义突变,使蛋白质翻译提前终止。该突变还严重影响了FtsZ2-1基因的mRNA水平。转基因互补实验进一步验证了该突变体表型是由于FtsZ2-1基因突变引起。本项工作为研究叶绿体分裂的机制提供了新材料和一些有用的线索。

An Arabidopsis thaliana chloroplast division mutant, chloroplast division 137 （pd137）, was obtained with an ethyl methane sulphonate （EMS） mutagenesis and mutant screening strategy. Compared with the wild type, pd137 showed an obviously different chloroplast phenotype. It has a much larger chloroplast size and a lower number of chloroplasts per cell than those in the wild type. Genetic analysis indicated that the mutant phenotype was controlled by a single recessive gene. pd137 was mapped to a region between molecular markers CH2-13.70 and CH2-16.0 on chromosome 2. In this region, FtsZ2-1 is the only identified gene which is involved in chloroplast division so far. DNA sequencing of the FtsZ2-1 gene in pd137 revealed a nonsense mutation at the 505th base. The mutation caused a premature translational termination of FtsZ2-1 protein and severely affected the mRNA level of FtsZ2-1 in pd137. Complementation experiment result confirmed that the chloroplast division defect ofpdl37 was due to the mutation in FtsZ2-1. Our study provides new material and some useful information for the study of chloroplast division.