Regulation of root-wave response by extra large and conventional G proteins in Arabidopsis thaliana
Regulation of root-wave response by extra large and conventional G proteins in Arabidopsis thaliana
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DOI：
10.1111/j.1365-313x.2008.03506.x
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发表时间：
2008-07-01
期刊：
影响因子：
7.2
通讯作者：
Assmann, Sarah M.
中科院分区：
文献类型：
--
作者：
Pandey, Sona;Monshausen, Gabriele B.;Assmann, Sarah M.
异源三聚体G蛋白由α、β和γ亚基组成，调节与植物生长和发育有关的许多基本过程。除了典型的异源三聚体G蛋白外，植物还含有一个小家族的超大G蛋白（XLG），其在C末端区域与G蛋白α亚基具有显著的相似性。在本文中，我们表明，三个XLG基因，XLG3，和G β亚基（AGB1）的拟南芥G蛋白异源三聚体的一个子集的根形态和生长反应的调节具体参与。基于T-DNA插入突变体表型的分析，XLG 3和AGB 1各自正调控根波动和根偏斜。由于这些反应是由物理和生理线索调节，我们评估了AGB1和XLG3在向重力性，向触性和激素反应中的作用。我们的数据表明，缺乏XLG3或AGB1基因的突变体对乙烯过敏，并显示生长反应与生长素运输的改变一致，同时保持基本上野生型的重力和触摸的物理线索的反应。这些结果表明，XLG3和AGB1蛋白调节植物根摆动和根偏斜反应的激素决定因素，并可能以组织特异性或信号特异性的方式相互作用。由于植物窝藏G α亚基基因，GPA1，敲除突变表现出野生型根波动和歪斜，我们的研究结果可能表明，AGB1亚基在这些过程中的功能，而不形成一个经典的G α β γ异源三聚体。
Heterotrimeric G proteins composed of alpha, beta and gamma subunits regulate a number of fundamental processes concerned with growth and development in plants. In addition to the canonical heterotrimeric G proteins, plants also contain a small family of extra large G proteins (XLGs) that show significant similarity to the G-protein alpha subunit in their C-terminal regions. In this paper we show that one of the three XLG genes, XLG3, and the G beta subunit (AGB1) of the Arabidopsis G-protein heterotrimer are specifically involved in the regulation of a subset of root morphological and growth responses. Based on analysis of T-DNA insertional mutant phenotypes, XLG3 and AGB1 each positively regulate root waving and root skewing. Since these responses are regulated by physical as well as physiological cues, we assessed the roles of AGB1 and XLG3 in gravitropism, thigmotropism and hormonal responses. Our data show that mutants lacking either XLG3 or AGB1 genes are hypersensitive to ethylene and show growth responses consistent with alterations in auxin transport, while maintaining an essentially wild-type response to the physical cues of gravity and touch. These results suggest that XLG3 and AGB1 proteins regulate the hormonal determinants of root-waving and root-skewing responses in plants and possibly interact in a tissue-specific or signal-specific manner. Because plants harboring knockout mutations in the G alpha subunit gene, GPA1, exhibit wild-type root waving and skewing, our results may indicate that the AGB1 subunit functions in these processes without formation of a classic G alpha beta gamma heterotrimer.