Dof轉錄因子家族是一類植物特有的轉錄因子家族，它們參與調控了多種生長發(fā)育過程,。在以前的研究中發(fā)現(xiàn),，大豆GmDOF4和GmDOF11可提高種子的脂肪酸含量并增加種子千粒重。本研究篩選了在擬南芥種子/花中高表達的Dof轉錄因子AtDOF4.2并進一步研究其功能,。
AtDOF4.2定位于細胞核,。應用酵母和原生質體系統(tǒng)的研究發(fā)現(xiàn)AtDOF4.2具有轉錄激活活性，而且其中的TMD基序對于該活性是必需的,。AtDOF4.2能結合具有AAAG核心元件的雙鏈DNA序列,，核心元件中任意堿基的突變會導致結合能力的喪失，側翼序列能對結合能力產生影響,。AtDOF4.2過表達植株表現(xiàn)為分枝增多的表型,，TMD基序突變降低了轉基因植物的分枝。上述表型可能是通過提高側枝發(fā)育相關基因STM,、TFL1和CYP83B1在轉基因株系中的表達來實現(xiàn)的,。AtDOF4.2過表達植株種子表皮細胞壁呈現(xiàn)坍塌狀，細胞間的輪廓變的不明顯,。通過GC/MS測定發(fā)現(xiàn),，種子表皮細胞壁中的膠質含量大幅下降，膠質主要成分多糖總含量以及各組分相對含量都發(fā)生了明顯變化,。細胞壁松弛相關基因AtEXPA9在轉基因植物中表達量有明顯提高，且AtDOF4.2能與AtEXPA9的啟動子結合,。dof4.2突變體沒有分枝和種皮的變化但其角果略長,，單株植物種子產量增加。AtDOF4.4是AtDOF4.2的一個類似物,，具有轉錄激活活性,。其過表達也促進側枝發(fā)育，但抑制角果長度及單株產量,。AtDOF4.4的RNAi株系呈現(xiàn)角果增長單株產量增加,。AtDOF4.2和AtDOF4.4表達都受到抑制的株系其表型與AtDOF4.4的RNAi株系類似。
這些研究表明,，AtDOF4.2和AtDOF4.4是調控植物分枝和種子/角果發(fā)育的重要因子,。對于揭示植物株型與產量的關系具有重要意義。該研究于2012年10月24日在線發(fā)表于Biochemical Journal,。共同培養(yǎng)的學生鄒洪峰和張玉芹是共同第一作者,。周奕華課題組也參與了相關工作。該項研究受973,，轉基因專項及自然基金資助,。（生物谷Bioon.com）
doi:10.1042/BJ20110060
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Transcription factor AtDOF4.2 regulates shoot branching and seed coat formation in Arabidopsis
Hong-Feng Zou, Yu-Qin Zhang, Wei Wei, Hao-Wei Chen, Qing-Xin Song, Yun-Feng Liu, Ming-Yu Zhao, Fang Wang, Bao-Cai Zhang, Qing Lin, Wan-Ke Zhang, Biao Ma, Yi-Hua Zhou, Jin-Song Zhang and Shou-Yi Chen
Plant-specific DOF-type transcription factors regulate various biological processes. Here, we characterized a silique-abundant gene AtDOF4.2 for its functions in Arabidopsis. AtDOF4.2 is localized in the nuclear region and has transcriptional activation activity in both yeast and plant protoplast assays. The Thr-Met-Asp motif in AtDOF4.2 is essential for its activation. AtDOF4.2-overexpressing plants exhibit an increased branching phenotype, and the mutation of Thr-Met-Asp motif in AtDOF4.2 significantly reduces the branching in transgenic plants. AtDOF4.2 may achieve this function through the upregulation of three branching-related genes, AtSTM, AtTFL1 and AtCYP83B1. The seeds of an AtDOF4.2-overexpressing plant show collapse-like morphology in epidermal cells of the seed coat. Mucilage contents and the concentration and composition of mucilage monosaccharides are significantly changed in the seed coat of transgenic plants. AtDOF4.2 may exert its effects on the seed epidermis through the direct binding and activation of the cell wall loosening-related gene AtEXPA9. The dof4.2 mutant did not exhibit changes in branching or its seed coat; however, the silique length and seed yield were increased. AtDOF4.4, which is a close homolog of AtDOF4.2, also promotes shoot branching and affects silique size and seed yield. Manipulation of these genes should have a practical use in the improvement of agronomic traits in important crops.
