水稻小粒矮秆突变体sgd1(t)的表型分析及基因克隆

Phenotyping and Gene Cloning of a Small-grain Dwarf Mutant sgd1(t) in Rice

在日本晴T-DNA突变体库中筛选得到小粒矮秆突变体sgd1(t),经多代自交稳定遗传。sgd1(t)出现植株矮化、粒型圆小、叶色深绿和颖壳厚实等表型。茎秆及颖壳细胞扫描电镜结果表明,sgd1(t)茎秆细胞不能形成正常细胞列、维管束发育异常;颖壳表皮细胞排列紧密但不规则;GA信号转导途径响应正常。遗传分析表明突变体sgd1(t)的矮秆性状受一对隐性核基因控制。采用图位克隆方法,将sgd1(t)定位于第9染色体短臂Indel标记DF13和DF26之间,物理距离约为230kb。该区间存在已克隆的矮秆基因BC12/GDD1。测序结果显示,sgd1(t)在该基因第4个外显子发生由G到T的单碱基突变,导致第186位保守氨基酸由甘氨酸突变为缬氨酸。

A small-grain dwarf mutant, designated as sgdl （t） , was identified from the T-DNA insertion mutant lines of Nipponbare.The mutant, genetically stable, was characterized by dwarf plant, small grain, dark green leaves and thick husk. Scanning electron microscope analysis on cell morphology of stem and hull revealed that stem cells in sgdl （t） failed to form normal cell column and vascular bundles, while epidermal cells with irregular shape in hulls were tightly packed, resulting in confusion in cell arrangement, and sad1 （t） was a GA-sensitive dwarf mutant. Genetic analysis showed that this trait of dwarfism was controlled by a pair of recessive nuclear gene. Through map-based cloning, the gene sad1 （t） was mapped in an interval of 230 kb between the markers DF13 and DF26 on the short arm of chromosome 9. There was a dwarf gene BC12/GDD1 in this region. Sequence analysis showed that sad1 （t） had a single-base suhstitution （G to T） in the fourth exon of the gene, resulting in the replacement of glycine by valine in 186th conservative amino acid.