Wang Hui-Wen, Zhang Bo, Hao Yu-Jun, Huang Jian, Tian Ai-Guo, Liao Yong, Zhang Jin-Song, Chen Shou-Yi
National Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Plant J. 2007 Nov;52(4):716-29. doi: 10.1111/j.1365-313X.2007.03268.x. Epub 2007 Sep 18.
Soybean is one of the most important leguminous seed crops among the oil crops. Although the pathways for lipid biosynthesis have been identified, the factors that regulate the biosynthetic pathways at the transcriptional level are largely unknown. Here, we report our findings on the involvement of soybean Dof-type transcription factor genes in the regulation of the lipid content in soybean seeds. We identified 28 Dof-type transcription factor genes in soybean plants, and these genes displayed diverse patterns of expression in various organs. Seven flower/pod-specific genes and one constitutively expressed gene were further investigated. The proteins encoded by these seven genes were localized in the nucleus, and exhibited different abilities for transcriptional activation and DNA binding. Two genes, GmDof4 and GmDof11, were found to increase the content of total fatty acids and lipids in GmDof4 and GmDof11 transgenic Arabidopsis seeds. We also found that the 1000-seed weight was increased in the GmDof4 and GmDof11 transgenic plants. Using microarray and DNA binding analysis, we found that the two Dof-like proteins, GmDof4 and GmDof11, activated the acetyl CoA carboxylase gene and long-chain-acyl CoA synthetase gene, respectively, by direct binding to the cis-DNA elements in their promoter regions. In addition, both proteins downregulated the storage protein gene, CRA1, through direct binding. These results suggest that the two GmDof genes may augment the lipid content of soybean seeds by upregulating genes that are associated with the biosynthesis of fatty acids.
大豆是油料作物中最重要的豆科种子作物之一。尽管脂质生物合成途径已被确定，但在转录水平上调节这些生物合成途径的因素仍 largely 未知。在此，我们报告了关于大豆 Dof 型转录因子基因参与调控大豆种子脂质含量的研究结果。我们在大豆植株中鉴定出 28 个 Dof 型转录因子基因，这些基因在不同器官中表现出多样的表达模式。对 7 个花/荚特异性基因和 1 个组成型表达基因进行了进一步研究。这 7 个基因编码的蛋白质定位于细胞核，并表现出不同的转录激活和 DNA 结合能力。发现两个基因，GmDof4 和 GmDof11，可增加 GmDof4 和 GmDof11 转基因拟南芥种子中的总脂肪酸和脂质含量。我们还发现 GmDof4 和 GmDof11 转基因植株的千粒重增加。通过微阵列和 DNA 结合分析，我们发现两个类 Dof 蛋白，GmDof4 和 GmDof11，分别通过直接结合其启动子区域的顺式 DNA 元件来激活乙酰辅酶 A 羧化酶基因和长链酰基辅酶 A 合成酶基因。此外，这两种蛋白质均通过直接结合下调贮藏蛋白基因 CRA1。这些结果表明，这两个 GmDof 基因可能通过上调与脂肪酸生物合成相关的基因来增加大豆种子的脂质含量。
