College of Forestry, Henan University of Science and Technology, Luoyang, 471003, People's Republic of China.
Beijing Key Laboratory of Grape Science and Enology and Key Laboratory of Plant Resource, Institute of Botany, the Chinese Academy of Sciences, Beijing, 100093, People's Republic of China.
BMC Plant Biol. 2019 Nov 7;19(1):478. doi: 10.1186/s12870-019-1993-6.
Resveratrol is a naturally occurring plant stilbene that exhibits a wide range of valuable biological and pharmacological properties. Although the beneficial effects of trans-resveratrol to human health and plant protection against fungal pathogens and abiotic stresses are well-established, yet little is known about the molecular mechanisms regulating stilbene biosynthesis in plant defense progress.
Here, we cloned and identified the Chinese wild grape (Vitis davidii) R2R3-MYB transcription factor VdMYB1, which activates defense responses against invading pathogen. VdMYB1 transcripts were significantly upregulated after inoculation with the grapevine powdery mildew fungus Erysiphe necator (Schw.) Burr. Transient expression analysis using onion epidermal cells and Arabidopsis thaliana protoplasts showed that VdMYB1 was localized in the nucleus. Yeast one-hybrid assays revealed that VdMYB1 acts as a transcriptional activator. Grapevine leaves transiently overexpressing VdMYB1 showed a lower number of fungal conidiophores compared with wild-type leaves. Overexpression of VdMYB1 in grapevine leaves did not alter the expression of genes in salicylic acid- and jasmonate-dependent pathways, but affected the expression of stilbene synthase (STS) genes, key regulators of flavonoid metabolism. Results of electrophoretic mobility shift assays and in vivo transcriptional activation assays showed that VdMYB1 binds to the MYB binding site (MYBBS) in the STS2 gene promoter, thus activating STS2 transcription. In heterologous expression assays using tobacco leaves, VdMYB1 activated STS2 gene expression and increased the accumulation of resveratrol.
Our study showed that VdMYB1 activates STS2 gene expression to positively regulate defense responses, and increases the content of resveratrol in leaves.
白藜芦醇是一种天然存在的植物芪，具有广泛的有价值的生物学和药理学特性。尽管反式白藜芦醇对人类健康和植物抵御真菌病原体和非生物胁迫的有益作用已得到充分证实，但对于调节植物防御过程中芪类生物合成的分子机制知之甚少。
在这里，我们克隆并鉴定了中国野生葡萄（Vitis davidii）R2R3-MYB 转录因子 VdMYB1，该因子可激活对入侵病原体的防御反应。接种葡萄白粉病真菌 Erysiphe necator（Schw.）Burr 后，VdMYB1 转录本显著上调。洋葱表皮细胞和拟南芥原生质体的瞬时表达分析表明，VdMYB1 定位于细胞核中。酵母单杂交测定表明，VdMYB1 作为转录激活因子起作用。与野生型叶片相比，瞬时过表达 VdMYB1 的葡萄叶片中的真菌产孢量较少。葡萄叶片中 VdMYB1 的过表达并未改变水杨酸和茉莉酸依赖途径中基因的表达，但影响了芪合酶（STS）基因的表达，STS 基因是类黄酮代谢的关键调节因子。电泳迁移率变动分析和体内转录激活分析的结果表明，VdMYB1 结合到 STS2 基因启动子中的 MYB 结合位点（MYBBS），从而激活 STS2 转录。使用烟草叶片进行的异源表达分析表明，VdMYB1 激活 STS2 基因表达并增加了白藜芦醇的积累。
我们的研究表明，VdMYB1 激活 STS2 基因表达以正向调节防御反应，并增加叶片中白藜芦醇的含量。
