Study of novel d1 alleles, defective mutants of the α subunit of heterotrimeric G-protein in rice
Study of novel d1 alleles, defective mutants of the α subunit of heterotrimeric G-protein in rice
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DOI：
10.1266/ggs.84.35
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发表时间：
2009-02-01
影响因子：
1.1
通讯作者：
Iwasaki, Yukimoto
中科院分区：
文献类型：
--
作者：
Oki, Katsuyuki;Inaba, Noriko;Iwasaki, Yukimoto
研究表明，异聚体G蛋白(G α) α亚基基因的破坏导致水稻矮化性状、叶片勃起和小种子结实。这些突变体被称为d1。我们研究了水稻Ga转录本和翻译产物在d1的10个等位基因中的表达谱，其中包括5个新发现的等位基因。RT-PCR检测了所有d1等位基因中G α基因的转录本。通过western blot检测，除d1-4外，d1等位基因的质膜部分未检测到Ga蛋白。在d1-4中，G α蛋白的gtp结合盒A发生了一个氨基酸变化，即使在这种情况下，G α蛋白也仅在质膜部分中检测到。考虑到G α蛋白在d1-8中仅缺失一个氨基酸的质膜部分中没有积累，可能G α的适当构象是G α蛋白在质膜中积累所必需的。d1的9个等位基因在种子大小和节间伸长模式方面表现出较强的表型，而d1-4表现出较弱的表型。由于已知油菜素内酯信号在d1中部分受损，我们比较了T65遗传背景下d1等位基因对24-表油菜素内酯（24-epiBL）的敏感性。只有d1-4表现出与野生型水稻相似的反应。结果表明，d1-4突变体在表型上是一个温和的等位基因，对外源施加的24-epiBL轻度低敏感性。
It has been shown that the disruption of the alpha-subunit gene of heterotorimeric G-proteins (G alpha) results in dwarf traits, the erection of leaves and the setting of small seeds in rice. These mutants are called d1. We have studied the expression profiles of the transcripts and translation products of rice Ga in ten alleles of d1 including five additional alleles newly identified. By RT-PCR, the transcripts of the G alpha gene were detected in the all d1 alleles. By western blot, the Ga proteins were not detected in the plasma membrane fractions of the d1 alleles with the exception of d1-4. In d1-4, one amino acid change in the GTP-binding box A of the G alpha protein was occurred and even in this case the G alpha protein was only just detectable in the plasma membrane fraction. Given that the G alpha protein did not accumulate in the plasma membrane fraction in d1-8 which has a deletion of just a single amino acid in the G alpha protein, it is likely that a proper conformation of the G alpha is necessary for accumulation of G alpha protein in the plasma membrane. Nine alleles of d1 showed a severer phenotype whilst d1-4 exhibited a mild phenotype with respect to seed size and elongation pattern of internodes. As brassinosteroid signaling was known to be partially impaired in d1s, the sensitivity to 24-epibrassinolide (24-epiBL) was compared among d1 alleles in a T65 genetic background. Only d1-4 showed responses similar to wild type rice. The results show that the d1-4 mutant is a mild allele in terms of the phenotype and mild hyposensitivity to the exogenously applied 24-epiBL.