Dof转录因子家族是一类植物特有的转录因子家族，它们参与调控了多种生长发育过程。在以前的研究中发现，大豆GmDOF4和GmDOF11可提高种子的脂肪酸含量并增加种子千粒重。本研究筛选了在拟南芥种子/花中高表达的Dof转录因子AtDOF4.2并进一步研究其功能。
AtDOF4.2定位于细胞核。应用酵母和原生质体系统的研究发现AtDOF4.2具有转录激活活性，而且其中的TMD基序对于该活性是必需的。AtDOF4.2能结合具有AAAG核心元件的双链DNA序列，核心元件中任意碱基的突变会导致结合能力的丧失，侧翼序列能对结合能力产生影响。AtDOF4.2过表达植株表现为分枝增多的表型，TMD基序突变降低了转基因植物的分枝。上述表型可能是通过提高侧枝发育相关基因STM、TFL1和CYP83B1在转基因株系中的表达来实现的。AtDOF4.2过表达植株种子表皮细胞壁呈现坍塌状，细胞间的轮廓变的不明显。通过GC/MS测定发现，种子表皮细胞壁中的胶质含量大幅下降，胶质主要成分多糖总含量以及各组分相对含量都发生了明显变化。细胞壁松弛相关基因AtEXPA9在转基因植物中表达量有明显提高，且AtDOF4.2能与AtEXPA9的启动子结合。dof4.2突变体没有分枝和种皮的变化但其角果略长，单株植物种子产量增加。AtDOF4.4是AtDOF4.2的一个类似物，具有转录激活活性。其过表达也促进侧枝发育，但抑制角果长度及单株产量。AtDOF4.4的RNAi株系呈现角果增长单株产量增加。AtDOF4.2和AtDOF4.4表达都受到抑制的株系其表型与AtDOF4.4的RNAi株系类似。
这些研究表明，AtDOF4.2和AtDOF4.4是调控植物分枝和种子/角果发育的重要因子。对于揭示植物株型与产量的关系具有重要意义。该研究于2012年10月24日在线发表于Biochemical Journal。共同培养的学生邹洪峰和张玉芹是共同第一作者。周奕华课题组也参与了相关工作。该项研究受973，转基因专项及自然基金资助。（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.
