拟南芥雄性不育突变体ms214的遗传与功能分析

Genetic and Functional Analysis of Arabidopsis thaliana Male Sterile Mutant ms214

经过EMS诱变、背景纯化以及遗传分析,得到一株隐性核基因控制的拟南芥雄性不育突变体ms214,用图位克隆的方法将突变基因MS214定位于拟南芥第一条染色体上顶端700kb的区间内。生物信息学分析发现,该区间内有一个与蜡质合成有关的基因CER1;测序分析表明在突变体ms214中,CER1基因第一个外显子上碱基由C509变成了U509的突变,导致CER蛋白在该处的氨基酸由脯氨酸170变成了亮氨酸170;等位实验结果表明ms214和cer1是等位突变体。ms214突变体的茎和果荚呈现出与野生型不同的亮绿色;组织切片观察结果表明,突变体花药发育各个时期无异常变化;扫描电镜观察发现ms214的茎和果荚的表皮没有蜡质的形成,但是突变体成熟花粉粒表面含油层异常,具有许多小的脂肪小滴。这些结果揭示了MS214蛋白质参与蜡质合成过程,而且脯氨酸170是该蛋白质行使功能所必需的。

Through EMS mutagenesis we obtained an Arabidopsis thaliana male sterile mutant named ms214 which is controlled by a single recessive nuclear gene. Map-based cloning strategy was used and MS214 gene was mapped to a region of 700 kb on the upper end of chromosome 1. Bioinformatics analysis revealed that there is a CER1 gene which is involved in wax biosynthesis in this region. Sequencing analysis indicated that ms214 mutant had a C to U base-pair change in the first exon of CER1 gene, which resulted in the replacement of a proline^170 by a leucine^170 residue in this region. Allelism tests indicated that MS214 and CER1 belong to the same locus. Unlike the wild type, the mutant displays glossy green stems and siliques. Cytology observation showed that there were no differences in an- ther development between the mutant and the wild type. Scanning Electron Microscopy （SEM） examination revealed that no wax was formed on the ms214 stems and siliques. But SEM examination on pollen grains showed that the pollen coat of the ms214 mutant was aberrant with numerous smaller lipid droplets. These data demonstrated that MS214 protein was involved in wax biosynthetic pathways, and proline^170 is very important for the function of this protein.