關(guān)鍵詞： 水稻 G蛋白 信號轉(zhuǎn)導(dǎo)
雖然異三聚體鳥嘌呤核苷結(jié)合蛋白（簡稱G蛋白）復(fù)合體是真核細(xì)胞中保守的一類重要信號轉(zhuǎn)導(dǎo)分子,但是它們在植物如何發(fā)揮作用的分子機(jī)制有待闡明,。前期研究結(jié)果表明水稻G蛋白α亞基RGA1（D1）參與了油菜素內(nèi)酯（BR）介導(dǎo)的信號響應(yīng)途徑,，但是究竟D1如何介導(dǎo)BR信號轉(zhuǎn)導(dǎo)的分子機(jī)制并不清楚。
中科院遺傳與發(fā)育生物學(xué)研究所薛勇彪,、謝旗和中國水稻所錢前研究組合作發(fā)現(xiàn)了一個新的水稻BR不敏感矮稈突變體—taihu dwarf1(tud1),。該突變體是由于一個編碼U-box E3泛素連接酶的基因突變所造成。詳細(xì)的分析表明tud1突變會導(dǎo)致水稻第二節(jié)間細(xì)胞縱向細(xì)胞層排列紊亂和外穎中薄壁細(xì)胞體積變小,，并且D1可以通過與TUD1直接相互作用來介導(dǎo)BR信號響應(yīng)通路,。該研究結(jié)果揭示了D1和TUD1共同作用介導(dǎo)了一條新的BR信號響應(yīng)通路。進(jìn)一步的研究發(fā)現(xiàn)TUD1在植物中具有保守性,，為進(jìn)一步提高水稻等作物產(chǎn)量提供了新的途徑,。
該研究結(jié)果于3月15日在線發(fā)表于國際主流刊物PLoS Genetics (DOI:10.1371/journal.pgen.1003391)，薛勇彪研究組的胡興明博士為論文的第一作者,，該項(xiàng)研究得到了科技部863計(jì)劃和國家自然科學(xué)基金委項(xiàng)目的資助,。(生物谷Bioon.com）
DOI:10.1371/journal.pgen.1003391
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The U-Box E3 Ubiquitin Ligase TUD1 Functions with a Heterotrimeric G α Subunit to Regulate Brassinosteroid-Mediated Growth in Rice
Xinming Hu,Qian Qian,Ting Xu,Yu'e Zhang,Guojun Dong,Ting Gao,Qi Xie,Yongbiao Xue mail
Heterotrimeric G proteins are an important group of signaling molecules found in eukaryotes. They function with G-protein-coupled-receptors (GPCRs) to transduce various signals such as steroid hormones in animals. Nevertheless, their functions in plants are not well-defined. Previous studies suggested that the heterotrimeric G protein α subunit known as D1/RGA1 in rice is involved in a phytohormone gibberellin-mediated signaling pathway. Evidence also implicates D1 in the action of a second phytohormone Brassinosteroid (BR) and its pathway. However, it is unclear how D1 functions in this pathway, because so far no partner has been identified to act with D1. In this study, we report a D1 genetic interactor Taihu Dwarf1 (TUD1) that encodes a functional U-box E3 ubiquitin ligase. Genetic, phenotypic, and physiological analyses have shown that tud1 is epistatic to d1 and is less sensitive to BR treatment. Histological observations showed that the dwarf phenotype of tud1 is mainly due to decreased cell proliferation and disorganized cell files in aerial organs. Furthermore, we found that D1 directly interacts with TUD1. Taken together, these results demonstrate that D1 and TUD1 act together to mediate a BR-signaling pathway. This supports the idea that a D1-mediated BR signaling pathway occurs in rice to affect plant growth and development.
