Fang Linchuan, Hou Yanlin, Wang Lijun, Xin Haiping, Wang Nian, Li Shaohua
Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China,
Plant Cell Rep. 2014 Oct;33(10):1629-40. doi: 10.1007/s00299-014-1642-3. Epub 2014 Jun 20.
High and low resveratrol (Res) contents in two cultivars are correlated with the expression abundance of Myb14 , which could directly activate transcriptional expression of stilbene synthase gene ( STS ). Resveratrol (3,5,4'-trihydroxystilbene) is one of the natural polyphenols produced by secondary metabolism in some plants. Stilbene synthase (STS) is the key enzyme for the final step of precursor formation of resveratrol (Res) in grapevines. In this study, we found that Res contents in ripe berry skin were completely different in two grape cultivars, namely, 'Z168' (Vitis monticola × Vitis riparia) with high-Res and 'Jingzaojing' (Vitis vinifera) with low-Res. Moreover, the level of expression of STS gene was higher in the ripe berry skin of 'Z168' than in that of 'Jingzaojing'. To further investigate the underlying mechanisms, we conducted a co-expression analysis through transcriptomic data. We confirmed that Myb14, an R2R3 Myb transcription factor, is the direct regulator of STS by binding to Box-L5 motif. Moreover, the expression pattern of Myb14 is associated with the variation of Res content. To test this prediction, we conducted a number of experiments in vivo and in vitro. The expression patterns of Myb14 and STS in grapevine leaves were identical under a series of stimulus. Myb14 showed higher expression in the ripe berry skin of 'Z168' than in that of 'Jingzaojing'. Yeast one-hybrid assay indicated that grapevine Myb14 could interact with the promoter of STS in vitro, and the transient overexpression of Myb14 promoted the expression of STS. Furthermore, co-expressing 35S::Myb14 in transgenic Arabidopsis could activate GUS expression promoted by STS promoter. Thus, Myb14 is the direct activator of STS, and its expression pattern is associated with Res content variation in grapes.
两个葡萄品种中白藜芦醇（Res）含量的高低与Myb14的表达丰度相关，Myb14可直接激活芪合酶基因（STS）的转录表达。白藜芦醇（3,5,4'-三羟基芪）是一些植物通过次生代谢产生的天然多酚之一。芪合酶（STS）是葡萄中白藜芦醇（Res）前体形成最后一步的关键酶。在本研究中，我们发现两个葡萄品种成熟浆果表皮中的Res含量完全不同，即高Res含量的‘Z168’（蒙自葡萄×河岸葡萄）和低Res含量的‘京早晶’（欧亚种葡萄）。此外，‘Z168’成熟浆果表皮中STS基因的表达水平高于‘京早晶’。为进一步探究潜在机制，我们通过转录组数据进行了共表达分析。我们证实，R2R3 Myb转录因子Myb14通过与Box-L5基序结合，是STS的直接调节因子。此外，Myb14的表达模式与Res含量的变化相关。为验证这一预测，我们在体内和体外进行了一系列实验。在一系列刺激下，葡萄叶片中Myb14和STS的表达模式相同。Myb14在‘Z168’成熟浆果表皮中的表达高于‘京早晶’。酵母单杂交试验表明，葡萄Myb14在体外可与STS启动子相互作用，Myb14的瞬时过表达促进了STS的表达。此外，在转基因拟南芥中共表达35S::Myb14可激活由STS启动子促进的GUS表达。因此，Myb14是STS的直接激活因子，其表达模式与葡萄中Res含量的变化相关。
