Department of Biology, Washington University, St Louis, MO 63130, USA.
Department of Biology, Washington University, St Louis, MO 63130, USA.
Mol Plant. 2009 Jul;2(4):790-802. doi: 10.1093/mp/ssp030. Epub 2009 Jun 2.
Single-repeat R3 MYB transcription factors like CPC (CAPRICE) are known to play roles in developmental processes such as root hair differentiation and trichome initiation. However, none of the six Arabidopsis single-repeat R3 MYB members has been reported to regulate flavonoid biosynthesis. We show here that CPC is a negative regulator of anthocyanin biosynthesis. In the process of using CPC to test GAL4-dependent driver lines, we observed a repression of anthocyanin synthesis upon GAL4-mediated CPC overexpression. We demonstrated that this is not due to an increase in nutrient uptake because of more root hairs. Rather, CPC expression level tightly controls anthocyanin accumulation. Microarray analysis on the whole genome showed that, of 37 000 features tested, 85 genes are repressed greater than three-fold by CPC overexpression. Of these 85, seven are late anthocyanin biosynthesis genes. Also, anthocyanin synthesis genes were shown to be down-regulated in 35S::CPC overexpression plants. Transient expression results suggest that CPC competes with the R2R3-MYB transcription factor PAP1/2, which is an activator of anthocyanin biosynthesis genes. This report adds anthocyanin biosynthesis to the set of programs that are under CPC control, indicating that this regulator is not only for developmental programs (e.g. root hairs, trichomes), but can influence anthocyanin pigment synthesis.
单重复 R3 MYB 转录因子，如 CPC（随心所欲），已知在发育过程中发挥作用，如根毛分化和毛状体起始。然而，拟南芥的六个单重复 R3 MYB 成员中没有一个被报道调节类黄酮生物合成。我们在这里表明 CPC 是花青素生物合成的负调节剂。在使用 CPC 测试 GAL4 依赖性驱动子系的过程中，我们观察到 GAL4 介导的 CPC 过表达会抑制花青素的合成。我们证明这不是由于根毛增多导致营养物质吸收增加所致。相反，CPC 的表达水平严格控制着花青素的积累。对整个基因组的微阵列分析表明，在测试的 37000 个特征中，有 85 个基因被 CPC 过表达抑制了三倍以上。在这 85 个基因中，有七个是晚期花青素生物合成基因。此外，花青素合成基因在 35S::CPC 过表达植物中也被下调。瞬时表达结果表明，CPC 与 R2R3-MYB 转录因子 PAP1/2 竞争，后者是花青素生物合成基因的激活剂。本报告将花青素生物合成添加到 CPC 控制的程序集中，表明该调节剂不仅适用于发育程序（例如根毛、毛状体），还可以影响花青素色素的合成。
