水稻矮化突变体G蛋白α亚基基因的结构和表达

利用γ-Co60辐射诱发水稻特光矮-2(Oryza sativa L.cv.TGA-2)产生变异,获得一种稳定遗传的新型水稻矮化突变体dwarf69.dwarf69和TGA-2及其杂交后代F1、F2、F3成熟期的株高数据表明矮化表型受一对隐性基因控制.进一步研究发现,虽然dwarf69和TGA-2的G蛋白α亚基基因(Rice G protein alpha-subunit,RGA)编码区核苷酸序列只有一个核苷酸的差异,但RGA在野生型TGA-2中的表达量明显高于在突变体dwarf69中的表达量.对矮化突变体dwarf69和野生型TGA-2的RGA基因5＇上游区的序列分析表明,dwarf69 RGA 5＇上游区比TGA-2RGA5＇上游区多出1076bp.首次报道水稻矮化突变体中的RGA5＇上游区序列与其野生种的RGA5＇上游区序列存在显著的差异.

Genetic Analysis and Molecular Characterization of the GTP Binding Protein Alpha-subunit Gene from Rice Dwarf Mutant dwarf 69

A dwarf mutant dwarf 69 was obtained from wildtype rice ( Oryza sativa L. var. TGA-2, indica) by gamma-ray irradiation with a Co60 source, dwarf 69 exhibited typic dwarf phenotypes, e. g. short, dark green leaves and low fertility. Genetic analysis showed that these dwarf phenotypes were conferred by a recessive mutant allele. Although only one nucleotide difference was found between the coding sequences of GTP binding protein alpha-subunit ( RGA ) gene from dwarf69 and its wildtype TGA-2, the expression level of the RGA gene in dwarf 69 was significantly higher than that in TGA-2. Further sequence analysis of the 5' upstream of the RGA genes from dwarf69 and TGA-2 revealed that two extra fragments, 973 bp and 103 bp respectively, were present in the 5' upstream of the RGA gene of dwarf69 but not in the RGA gene of TGA-2. These results indicated that the mutation of the 5' upstream of the RGA gene might affect RGA expression in rice and therefor result in the dwarf phenotypes.