據(jù)中國(guó)農(nóng)業(yè)科學(xué)院最新消息,，由該院作物科學(xué)研究所所長(zhǎng)萬(wàn)建民領(lǐng)導(dǎo)的課題組，通過(guò)花粉培養(yǎng)研究構(gòu)建了獨(dú)具特色的一系列水稻突變體材料,，對(duì)其中一個(gè)分蘗顯著增加的多分蘗突變體Tiller Enhancer（TE）的基因克隆和功能分析,，發(fā)現(xiàn)了調(diào)控水稻分蘗的一個(gè)新的重要分子機(jī)制。
據(jù)萬(wàn)建民介紹,，水稻分蘗是影響水稻產(chǎn)量的一個(gè)重要因子,，同時(shí)分蘗也是植物生物學(xué)研究中關(guān)于植物株型建成的一個(gè)中心議題。其基本原理是,，MONOCULM 1（MOC1）編碼一個(gè)植物特有的GRAS轉(zhuǎn)錄因子,，控制分蘗芽的起始和生長(zhǎng)等過(guò)程，是水稻分蘗的主控因子,。此前,，其自身的調(diào)控機(jī)理尚不清楚。
通過(guò)對(duì)TE基因功能的深入研究,，萬(wàn)建民課題組揭示了TE通過(guò)調(diào)控MOC1的降解來(lái)調(diào)控水稻分蘗的重要分子機(jī)理,。10多年來(lái)，課題組的秦瑞珍等通過(guò)對(duì)多分蘗突變體TE以及少分蘗突變體MOC1—5的遺傳分析,，發(fā)現(xiàn)TE作用于MOC1的上游,；生化研究發(fā)現(xiàn)TE和MOC1位于同一個(gè)蛋白復(fù)合物中并直接互作；分子遺傳學(xué)分析發(fā)現(xiàn),，TE編碼一個(gè)細(xì)胞分裂后期啟動(dòng)復(fù)合物（簡(jiǎn)稱APC/C）的激活蛋白,，與APC/C復(fù)合體的CDC27亞基直接互作。APC/C是真核生物中功能高度保守的一種E3泛素連接酶,，參與降解細(xì)胞周期中的關(guān)鍵調(diào)控因子,，從而促進(jìn)細(xì)胞周期的進(jìn)程。課題組證明TE直接作用于MOC1,，導(dǎo)致后者以依賴于泛素-26S蛋白酶系統(tǒng)的方式降解,。該研究揭示了APC/C TE參與了調(diào)控植物株型建成的新功能。
對(duì)TE研究的主要成果日前發(fā)表于在線出版的《自然·通訊》Nature Communications上,。（生物谷Bioon.com）
doi:10.1038/ncomms1716
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Rice APC/CTE controls tillering by mediating the degradation of MONOCULM 1
Qibing Lin, Dan Wang, Hui Dong, Suhai Gu, Zhijun Cheng, Jie Gong, Ruizhen Qin, Ling Jiang, Gang Li, Jiu Lin Wang, Fuqing Wu, Xiuping Guo, Xin Zhang, Cailin Lei, Haiyang Wang & Jianmin Wan
Rice MONOCULM 1 (MOC1) and its orthologues LS/LAS (lateral suppressor in tomato and Arabidopsis) are key promoting factors of shoot branching and tillering in higher plants. However, the molecular mechanisms regulating MOC1/LS/LAS have remained elusive. Here we show that the rice tiller enhancer (te) mutant displays a drastically increased tiller number. We demonstrate that TE encodes a rice homologue of Cdh1, and that TE acts as an activator of the anaphase promoting complex/cyclosome (APC/C) complex. We show that TE coexpresses with MOC1 in the axil of leaves, where the APC/CTE complex mediates the degradation of MOC1 by the ubiquitin–26S proteasome pathway, and consequently downregulates the expression of the meristem identity gene Oryza sativa homeobox 1, thus repressing axillary meristem initiation and formation. We conclude that besides having a conserved role in regulating cell cycle, APC/CTE has a unique function in regulating the plant-specific postembryonic shoot branching and tillering, which are major determinants of plant architecture and grain yield.
