The regulator of G-protein signaling proteins involved in sugar and abscisic acid signaling in Arabidopsis seed germination
The regulator of G-protein signaling proteins involved in sugar and abscisic acid signaling in Arabidopsis seed germination
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DOI：
10.1104/pp.105.069872
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发表时间：
2006-01-01
期刊：
影响因子：
7.4
通讯作者：
Zhang, JH
中科院分区：
文献类型：
--
作者：
Chen, Y;Ji, FF;Zhang, JH
最近在拟南芥（Arabidopsis thaliana；命名为AtRGS1）中发现的g蛋白信号（RGS）蛋白调节因子具有预测的七跨膜结构和具有gtpase加速活性的RGS盒子，从而使g蛋白介导的信号脱敏。本研究探讨了AtRGS1蛋白在拟南芥种子萌发中的作用及其与糖和脱落酸（ABA）的相互作用。利用携带编码拟南芥RGS蛋白（AtRGS1）和G蛋白α亚基（AtGPA1）基因零突变的种子（分别命名为rgs1-2和gpa1-3），我们的遗传证据证明了AtRGS1蛋白参与了种子萌发的调节。与野生型哥伦比亚-0和gpa1-3相比，rgs1-2种子不需要分层，成熟后的过程对种子萌发没有影响。此外，rgs1-2种子萌发对葡萄糖（Glc）和蔗糖不敏感。rgs1-2突变体对Glc和蔗糖的不敏感不是由于可能的渗透胁迫，因为在相同浓度的甘露醇和山梨醇处理下，rgs1-2突变体种子的萌发表现出与gpa1-3突变体和野生型相同的反应。gpa1-3种子萌发对外源ABA敏感，rgs1-2种子萌发对外源ABA不敏感。当内源ABA生物合成受到抑制时，外源ABA和Glc对种子萌发的抑制作用明显减弱。过表达AtRGS1的种子萌发对Glc和ABA均有超敏反应。内源ABA活性水平及NCED3和ABA2基因表达分析表明，Glc显著促进了哥伦比亚萌发种子中ABA的生物合成，并增加了NCED3和ABA2基因的表达，而rgs1-2突变体种子中则没有。这些数据表明AtRGS1蛋白参与了种子萌发的调控。rgs1-2突变体种子萌发对Glc的低敏感性可能是种子萌发过程中ABA生物合成受损的结果。
The regulator of G-protein signaling ( RGS) proteins, recently identified in Arabidopsis ( Arabidopsis thaliana; named as AtRGS1), has a predicted seven-transmembrane structure as well as an RGS box with GTPase-accelerating activity and thus desensitizes the G-protein-mediated signaling. The roles of AtRGS1 proteins in Arabidopsis seed germination and their possible interactions with sugars and abscisic acid ( ABA) were investigated in this study. Using seeds that carry a null mutation in the genes encoding RGS protein ( AtRGS1) and the alpha-subunit ( AtGPA1) of the G protein in Arabidopsis ( named rgs1-2 and gpa1-3, respectively), our genetic evidence proved the involvement of the AtRGS1 protein in the modulation of seed germination. In contrast to wild-type Columbia-0 and gpa1-3, stratification was found not to be required and the after- ripening process had no effect on the rgs1-2 seed germination. In addition, rgs1-2 seed germination was insensitive to glucose ( Glc) and sucrose. The insensitivities of rgs1-2 to Glc and sucrose were not due to a possible osmotic stress because the germination of rgs1-2 mutant seeds showed the same response as those of gpa1-3 mutants and wild type when treated with the same concentrations of mannitol and sorbitol. The gpa1-3 seed germination was hypersensitive while rgs1-2 was less sensitive to exogenous ABA. The different responses to ABA largely diminished and the inhibitory effects on seed germination by exogenous ABA and Glc were markedly alleviated when endogenous ABA biosynthesis was inhibited. Hypersensitive responses of seed germination to both Glc and ABA were also observed in the overexpressor of AtRGS1. Analysis of the active endogenous ABA levels and the expression of NCED3 and ABA2 genes showed that Glc significantly stimulated the ABA biosynthesis and increased the expression of NCED3 and ABA2 genes in germinating Columbia seeds, but not in rgs1-2 mutant seeds. These data suggest that AtRGS1 proteins are involved in the regulation of seed germination. The hyposensitivity of rgs1-2 mutant seed germination to Glc might be the result of the impairment of ABA biosynthesis during seed germination.