School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
Plant Physiol. 2023 Aug 3;192(4):2628-2639. doi: 10.1093/plphys/kiad270.
Transcriptional regulation mediated by combinatorial interaction of transcription factors (TFs) is a key molecular mechanism modulating plant development and metabolism. Basic leucine zipper (bZIP) TFs play important roles in various plant developmental and physiological processes. However, their involvement in fatty acid biosynthesis is largely unknown. Arabidopsis (Arabidopsis thaliana) WRINKLED1 (WRI1) is a pivotal TF in regulation of plant oil biosynthesis and interacts with other positive and negative regulators. In this study, we identified two bZIP TFs, bZIP21 and bZIP52, as interacting partners of AtWRI1 by yeast-two-hybrid (Y2H)-based screening of an Arabidopsis TF library. We found that coexpression of bZIP52, but not bZIP21, with AtWRI1 reduced AtWRI1-mediated oil biosynthesis in Nicotiana benthamiana leaves. The AtWRI1-bZIP52 interaction was further verified by Y2H, in vitro pull-down, and bimolecular fluorescence complementation assays. Transgenic Arabidopsis plants overexpressing bZIP52 showed reduced seed oil accumulation, while the CRISPR/Cas9-edited bzip52 knockout mutant exhibited increased seed oil accumulation. Further analysis revealed that bZIP52 represses the transcriptional activity of AtWRI1 on the fatty acid biosynthetic gene promoters. Together, our findings suggest that bZIP52 represses fatty acid biosynthesis genes through interaction with AtWRI1, resulting in a reduction of oil production. Our work reports a previously uncharacterized regulatory mechanism that enables fine-tuning of seed oil biosynthesis.
转录因子（TFs）的组合相互作用介导的转录调控是调节植物发育和代谢的关键分子机制。碱性亮氨酸拉链（bZIP）TFs 在各种植物发育和生理过程中发挥重要作用。然而，它们在脂肪酸生物合成中的作用在很大程度上是未知的。拟南芥（Arabidopsis thaliana）WRINKLED1（WRI1）是调节植物油脂生物合成的关键 TF，与其他正、负调控因子相互作用。在这项研究中，我们通过拟南芥 TF 文库的酵母双杂交（Y2H）筛选，鉴定了两个 bZIP TF，bZIP21 和 bZIP52，它们是 AtWRI1 的相互作用伙伴。我们发现，bZIP52 与 AtWRI1 的共表达而非 bZIP21 与 AtWRI1 的共表达降低了 AtWRI1 在烟草原生质体叶片中介导的油脂生物合成。AtWRI1-bZIP52 相互作用进一步通过 Y2H、体外下拉和双分子荧光互补测定得到验证。过表达 bZIP52 的转基因拟南芥植物表现出种子油积累减少，而 CRISPR/Cas9 编辑的 bzip52 敲除突变体表现出种子油积累增加。进一步分析表明，bZIP52 抑制 AtWRI1 在脂肪酸生物合成基因启动子上的转录活性。总之，我们的研究结果表明，bZIP52 通过与 AtWRI1 相互作用抑制脂肪酸生物合成基因的转录，从而导致产油量减少。我们的工作报告了一个以前未被描述的调控机制，该机制可以实现种子油生物合成的精细调控。
