College of Forestry, Shenyang Agricultural University, Shenyang, 110866, China.
Key Laboratory of Forest Tree Genetics, Breeding and Cultivation of Liaoning Province, Shenyang, 110866, China.
Plant J. 2024 Aug;119(4):1737-1750. doi: 10.1111/tpj.16881. Epub 2024 Jun 12.
Anthocyanin is an important pigment responsible for plant coloration and beneficial to human health. Kale (Brassica oleracea var. acephala), a primary cool-season flowers and vegetables, is an ideal material to study anthocyanin biosynthesis and regulation mechanisms due to its anthocyanin-rich leaves. However, the underlying molecular mechanism of anthocyanin accumulation in kale remains poorly understood. Previously, we demonstrated that BoDFR1 is a key gene controlling anthocyanin biosynthesis in kale. Here, we discovered a 369-bp InDel variation in the BoDFR1 promoter between the two kale inbred lines with different pink coloration, which resulted in reduced transcriptional activity of the BoDFR1 gene in the light-pink line. With the 369-bp insertion as a bait, an R2R3-MYB repressor BoMYB4b was identified using the yeast one-hybrid screening. Knockdown of the BoMYB4b gene led to increased BoDFR1 expression and anthocyanin accumulation. An E3 ubiquitin ligase, BoMIEL1, was found to mediate the degradation of BoMYB4b, thereby promoting anthocyanin biosynthesis. Furthermore, the expression level of BoMYB4b was significantly reduced by light signals, which was attributed to the direct repression of the light-signaling factor BoMYB1R1 on the BoMYB4b promoter. Our study revealed that a novel regulatory module comprising BoMYB1R1, BoMIEL1, BoMYB4b, and BoDFR1 finely regulates anthocyanin accumulation in kale. The findings aim to establish a scientific foundation for genetic improvement of leaf color traits in kale, meanwhile, providing a reference for plant coloration studies.
花椰菜（ Brassica oleracea var. acephala ）是一种主要的冷季花卉和蔬菜，由于其富含花青素的叶子，是研究花青素生物合成和调控机制的理想材料。花椰菜是一种重要的色素，负责植物的颜色，对人类健康有益。然而，花椰菜中花青素积累的潜在分子机制仍知之甚少。以前，我们证明 BoDFR1 是控制花椰菜花青素生物合成的关键基因。在这里，我们在两个具有不同粉红色颜色的花椰菜自交系之间发现了 BoDFR1 启动子中的 369bp InDel 变异，导致光粉红色系中 BoDFR1 基因的转录活性降低。利用 369bp 插入作为诱饵，通过酵母单杂交筛选鉴定出一个 R2R3-MYB 抑制子 BoMYB4b。敲低 BoMYB4b 基因导致 BoDFR1 表达和花青素积累增加。发现一个 E3 泛素连接酶 BoMIEL1 介导 BoMYB4b 的降解，从而促进花青素的生物合成。此外，光信号显著降低了 BoMYB4b 的表达水平，这归因于光信号因子 BoMYB1R1 对 BoMYB4b 启动子的直接抑制。我们的研究揭示了一个由 BoMYB1R1 、 BoMIEL1 、 BoMYB4b 和 BoDFR1 组成的新调控模块，精细调节花椰菜中花青素的积累。这些发现旨在为花椰菜叶片颜色性状的遗传改良建立科学基础，同时为植物颜色研究提供参考。
