Centre for Research in Agricultural Genomics (CRAG), Consortium CSIC-IRTA-UAB, 08034 Barcelona, Spain.
Plant J. 2010 Nov;64(4):633-44. doi: 10.1111/j.1365-313X.2010.04363.x. Epub 2010 Oct 8.
Few regulators of phenylpropanoids have been identified in monocots having potential as biofuel crops. Here we demonstrate the role of the maize (Zea mays) R2R3-MYB factor ZmMYB31 in the control of the phenylpropanoid pathway. We determined its in vitro consensus DNA-binding sequence as ACC(T)/(A) ACC, and chromatin immunoprecipitation (ChIP) established that it interacts with two lignin gene promoters in vivo. To explore the potential of ZmMYB31 as a regulator of phenylpropanoids in other plants, its role in the regulation of the phenylpropanoid pathway was further investigated in Arabidopsis thaliana. ZmMYB31 downregulates several genes involved in the synthesis of monolignols and transgenic plants are dwarf and show a significantly reduced lignin content with unaltered polymer composition. We demonstrate that these changes increase cell wall degradability of the transgenic plants. In addition, ZmMYB31 represses the synthesis of sinapoylmalate, resulting in plants that are more sensitive to UV irradiation, and induces several stress-related proteins. Our results suggest that, as an indirect effect of repression of lignin biosynthesis, transgenic plants redirect carbon flux towards the biosynthesis of anthocyanins. Thus, ZmMYB31 can be considered a good candidate for the manipulation of lignin biosynthesis in biotechnological applications.
在具有生物燃料作物潜力的单子叶植物中，鉴定出的苯丙素类物质调控因子很少。在这里，我们证明了玉米（Zea mays）R2R3-MYB 因子 ZmMYB31 在苯丙素途径调控中的作用。我们确定了其体外的保守 DNA 结合序列为 ACC(T)/(A)ACC，并通过染色质免疫沉淀（ChIP）确定其在体内与两个木质素基因启动子相互作用。为了探索 ZmMYB31 在其他植物中作为苯丙素类物质调控因子的潜力，我们进一步在拟南芥中研究了其在苯丙素途径调控中的作用。ZmMYB31 下调了几个参与单酚醇合成的基因，转基因植物矮小，木质素含量显著降低，聚合物组成不变。我们证明这些变化增加了转基因植物细胞壁的可降解性。此外，ZmMYB31 抑制了肉桂酰基马来酰亚胺的合成，导致植物对紫外线照射更为敏感，并诱导了几种应激相关蛋白。我们的研究结果表明，作为木质素生物合成抑制的间接效应，转基因植物将碳通量重新定向到花青素的生物合成上。因此，ZmMYB31 可以被认为是生物技术应用中木质素生物合成操纵的一个良好候选因子。
