College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China.
College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Plant Physiol Biochem. 2024 Oct;215:108964. doi: 10.1016/j.plaphy.2024.108964. Epub 2024 Jul 23.
Rehmannia piasezkii is a kind of medicinal plants, of the Orobanchaceae family, and well known for its large pink or purple corolla. However, no research on the molecular mechanism of flower color formation in R. piasezkii has been conducted so far. In this study, we investigated the transcriptome of root, stem, leaf and corollas of R. piasezkii using transcriptome sequencing technology and assembled 144,582 unigenes. A total of 58 anthocyanin biosynthetic genes were identified in the R. piasezkii transcriptome, fourteen of which were highly correlated with anthocyanin content, especially RpF3H2, RpDFR2, RpANS1, RpANS2 and RpUFGT. Totally, 35 MYB genes with FPKM values greater than 5 were identified in the R. piasezkii transcriptome, including an R2R3 MYB transcriptional factor RpMYB1, which belongs to subgroup 6 of the R2R3 MYB family. Agrobacterium-mediated transient expression of Nicotiana benthamiana revealed that overexpression of RpMYB1 could activate the expression of structural genes in anthocyanin synthesis pathway and promote the accumulation of anthocyanins in N. benthamiana leaves, indicating that RpMYB1 is a positive regulator of anthocyanin synthesis. Furthermore, combined transient overexpression of RpMYB1 with RpANS1, RpMYB1+RpANS1 with other structural genes all could further enhance the accumulation of anthocyanins in N. benthamiana leaves. Permanent overexpression of RpMYB1 in R. glutinosa promoted anthocyanin accumulation and expression levels of RgCHS, RgF3H, RgDFR and RgANS. Further evidence from dual-luciferase assay suggested that RpMYB1 could bind to the promoter of RpDFR2 and hence activating its expression. These findings provide insight into the molecular regulation in anthocyanin biosynthesis in R. piasezkii and provide valuable genetic resources for the genetic improvement of flower color.
怀地黄是玄参科地黄属植物，以其大而粉红色或紫色的花冠而闻名。然而，目前还没有关于怀地黄花色形成的分子机制的研究。在这项研究中，我们使用转录组测序技术对怀地黄的根、茎、叶和花冠进行了转录组研究，组装了 144582 条 unigenes。在怀地黄转录组中共鉴定出 58 个花青苷生物合成基因，其中 14 个与花青苷含量高度相关，特别是 RpF3H2、RpDFR2、RpANS1、RpANS2 和 RpUFGT。在怀地黄转录组中共鉴定出 35 个 MYB 基因，其 FPKM 值大于 5，包括属于 R2R3 MYB 家族第 6 亚组的 RpMYB1。农杆菌瞬时表达在烟草原生质体中发现，过表达 RpMYB1 可以激活花色苷合成途径中结构基因的表达，并促进烟草原生质体叶片中花色苷的积累，表明 RpMYB1 是花色苷合成的正调控因子。此外，RpMYB1 与 RpANS1 的瞬时共表达，RpMYB1+RpANS1 与其他结构基因的共表达都可以进一步增强烟草原生质体叶片中花色苷的积累。怀地黄中 RpMYB1 的永久性过表达促进了花色苷的积累和 RgCHS、RgF3H、RgDFR 和 RgANS 的表达水平。双荧光素酶报告基因实验进一步表明，RpMYB1 可以与 RpDFR2 的启动子结合，从而激活其表达。这些发现为怀地黄花色苷生物合成的分子调控提供了新的见解，并为花色遗传改良提供了有价值的遗传资源。
