State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China, Ministry of Agriculture, Yangling, 712100, Shaanxi, China.
Planta. 2019 Dec;250(6):1997-2007. doi: 10.1007/s00425-019-03276-2. Epub 2019 Sep 17.
In grape (Vitis), stilbene phytoalexins can either be in situ synthesized or transported to the site of response during powdery mildew infection, enhancing disease resistance. Resveratrol is a phytoprotective stilbenoid compound that is synthesized by stilbene synthase (STS) in response to biotic and abiotic stresses, and is also known to have health benefits in the human diet. We have previously shown that transgenic Vitis vinifera cv. Thompson Seedless plants overexpressing a stilbene synthase gene, VqSTS6, from wild Chinese Vitis quinquangularis had a higher stilbenoid content, leading to an enhanced resistance to powdery mildew (Uncinula necator (Schw.) Burr). However, the biosynthesis and transportation in the plant tissue under powdery mildew infection are still unclear. Here, inhibitor and micro-grafting technologies were used to study the accumulation of resveratrol following powdery mildew infection. We observed that the levels of STS expression and stilbenoids increased in response to powdery mildew infection. Powdery mildew and inhibitor treatment on detached grape branches showed that resveratrol was in situ synthesized. Experiments with grafted plantlets showed that the abundance of stilbenoid compounds increased in the shoot during VqSTS6 overexpression in the root, while VqSTS6-Flag fusion was not tranported to the scions and only expressed in the transgenic rootstocks. Compared with wild-type Thompson Seedless plants, the non-transgenic/VqSTS6 transgenic (scion/rootstock) grafted Thompson Seedless plantlets exhibited increased resistance to powdery mildew. In addition, overexpression of VqSTS6 in roots led to increased levels of stilbenoid compounds in five other European grape varieties (V. vinifera cvs. Chardonnay, Perlette, Cabernet Sauvignon, Riesling and Muscat Hamburg). In conclusion, stilbenoid compounds can be either in situ synthesized or transported to the site of powdery mildew infection, and overexpression of VqSTS6 in the root promotes stilbenoids accumulation and disease resistance in European grapevine varieties.
在葡萄（Vitis）中，芪类植物抗毒素可以在原位合成，也可以在白粉病感染时运输到反应部位，从而增强抗病性。白藜芦醇是一种植物保护芪类化合物，它是由芪合酶（STS）在生物和非生物胁迫下合成的，也被认为对人类饮食有益健康。我们之前已经表明，过表达来自野生中国五叶葡萄（Vitis quinquangularis）的芪合酶基因 VqSTS6 的转基因葡萄（Vitis vinifera cv. Thompson Seedless）植株具有更高的芪类含量，从而增强了对白粉病（Uncinula necator（Schw.）Burr）的抗性。然而，在白粉病感染下植物组织中的生物合成和运输仍不清楚。在这里，我们使用抑制剂和微嫁接技术研究了白粉病感染后白藜芦醇的积累。我们观察到，STS 表达和芪类物质的水平随着白粉病感染而增加。白粉病和抑制剂处理离体葡萄枝表明，白藜芦醇是原位合成的。嫁接苗实验表明，在根中过表达 VqSTS6 时， shoot 中芪类化合物的丰度增加，而 VqSTS6-Flag 融合物未运输到接穗中，仅在转基因砧木中表达。与野生型 Thompson Seedless 植株相比，非转基因/VqSTS6 转基因（接穗/砧木）嫁接的 Thompson Seedless 苗对白粉病的抗性增强。此外，在根中过表达 VqSTS6 导致其他五个欧洲葡萄品种（V. vinifera cvs. Chardonnay、Perlette、Cabernet Sauvignon、Riesling 和 Muscat Hamburg）中芪类化合物的水平升高。总之，芪类化合物可以在原位合成，也可以运输到白粉病感染部位，在根中过表达 VqSTS6 促进了欧洲葡萄品种芪类化合物的积累和抗病性。
