Wang Chaoxia, Wu Jiao, Zhang Yali, Lu Jiang
The Viticulture and Enology Program, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 10008, People's Republic of China.
Center for Viticulture and Enology, School of Agriculture Biology, Shanghai Jiao Tong University, Shanghai, 200024, People's Republic of China.
Protoplasma. 2018 Jan;255(1):95-107. doi: 10.1007/s00709-017-1118-8. Epub 2017 Jun 26.
Downy mildew (DM), one of the most devastating grape diseases worldwide, is caused by the biotrophic oomycete Plasmopara viticola (Pv). In general, grapevine responds to Pv infection with the accumulation of phytoalexins as part of the innate immune system, and diverse phytoalexins are induced on grapevines with different DM-resistance levels in response to Pv invasion. However, the regulation of phytoalexin biosynthesis during grapevine against Pv is still unclear. Herein, we detected stilbenes by UPLC-ESI-MS/MS and found that resveratrol was accumulated to higher level and earlier in the DM-immune Muscadinia rotundifolia 'Noble' than that in the DM-susceptible Vitis vinifera 'Thompson Seedless' after Pv inoculation. Additionally, a considerable amount of pterostilbene and ε-viniferin was found in 'Noble', while a little was detected in 'Thompson Seedless'. Resveratrol was glycosylated into piceid both in 'Noble' and 'Thompson Seedless' after Pv inoculation. The qPCR analysis of gene expression indicated that the resveratrol-synthesis gene (STS) was induced by Pv inoculation earlier in 'Noble' than that in 'Thompson Seedless', while the pterostilbene-synthesis gene (ROMT) was induced in 'Noble' but not in 'Thompson Seedless' at all. The piceid-synthesis gene (GT) was generally up-regulated in both cultivars. Sequence analysis of STS, ROMT, and GT promoters revealed that they contained cis-regulatory elements responsive to phytohormones and pathogens. Following Pv inoculation, the level of SA, MeJA, and ABA was found to be consistently higher in 'Noble' than those in 'Thompson Seedless'. The results of exogenous hormone elicitation further demonstrated that the accumulation of stilbenes was regulated by phytohormones. The earlier and higher accumulation of phytohormones and consequent induction of stilbene synthesis may play an important role in grapevine defense against downy mildew disease.
霜霉病（DM）是全球最具破坏性的葡萄病害之一，由活体营养型卵菌葡萄生单轴霉（Pv）引起。一般来说，葡萄通过积累植保素作为先天免疫系统的一部分来应对Pv感染，并且在不同抗霜霉病水平的葡萄植株上，会因Pv入侵而诱导产生多种植保素。然而，葡萄植株抵御Pv过程中植保素生物合成的调控机制仍不清楚。在此，我们通过超高效液相色谱-电喷雾串联质谱（UPLC-ESI-MS/MS）检测芪类化合物，发现接种Pv后，抗霜霉病的圆叶葡萄‘贵族’中白藜芦醇积累水平更高且更早，相比之下，感霜霉病的欧亚种葡萄‘汤普森无核’中白藜芦醇的积累水平较低。此外，在‘贵族’中发现了大量的紫檀芪和ε-葡萄素，而在‘汤普森无核’中仅检测到少量。接种Pv后，‘贵族’和‘汤普森无核’中的白藜芦醇均糖基化为云杉新苷。基因表达的qPCR分析表明，接种Pv后，白藜芦醇合成基因（STS）在‘贵族’中比在‘汤普森无核’中更早被诱导，而紫檀芪合成基因（ROMT）在‘贵族’中被诱导，但在‘汤普森无核’中根本未被诱导。云杉新苷合成基因（GT）在两个品种中总体上均上调。对STS、ROMT和GT启动子的序列分析表明，它们含有对植物激素和病原体有响应的顺式作用元件。接种Pv后，发现‘贵族’中水杨酸（SA）、茉莉酸甲酯（MeJA）和脱落酸（ABA）的水平始终高于‘汤普森无核’。外源激素诱导的结果进一步证明，芪类化合物的积累受植物激素调控。植物激素更早且更高水平的积累以及随之而来的芪类化合物合成诱导可能在葡萄抵御霜霉病中起重要作用。
