Smit Samuel Jacobus, Vivier Melané Alethea, Young Philip Richard
Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, Stellenbosch, South Africa.
Front Plant Sci. 2019 Feb 21;10:177. doi: 10.3389/fpls.2019.00177. eCollection 2019.
Grapevine ( L.) terpene synthases (VviTPS) are responsible for the biosynthesis of terpenic volatiles. Volatile profiling of nine commercial wine cultivars showed unique cultivar-specific variation in volatile terpenes emitted from grapevine flowers. The flower chemotypes of three divergent cultivars, Muscat of Alexandria, Sauvignon Blanc and Shiraz were subsequently investigated at two flower developmental stages (EL-18 and -26). The cultivars displayed unique flower sesquiterpene compositions that changed during flower organogenesis and the profiles were dominated by either ()-β-farnesene, ()-α-farnesene or (+)-valencene. remapping of microarray probes to gene models allowed for a meta-analysis of expression patterns in the grape gene atlas to identify genes that could regulate terpene biosynthesis in flowers. Selected sesquiterpene synthase genes were isolated and functionally characterized in three cultivars. Genotypic differences that could be linked to the function of a targeted gene model resulted in the isolation of a novel and cultivar-specific single product sesquiterpene synthase from Muscat of Alexandria flowers (VvivMATPS10), synthesizing ()-β-farnesene as its major volatile. Furthermore, we identified structural variations (SNPs, InDels and splice variations) in the characterized genes that potentially impact enzyme function and/or volatile sesquiterpene production in a cultivar-specific manner.
葡萄（Vitis vinifera L.）萜烯合酶（VviTPS）负责萜类挥发物的生物合成。对9个商业酿酒葡萄品种的挥发性成分分析表明，葡萄花释放的挥发性萜类物质存在独特的品种特异性差异。随后，在两个花发育阶段（EL-18和-26）对三个不同品种——亚历山大麝香葡萄、长相思和设拉子的花化学类型进行了研究。这些品种表现出独特的花倍半萜组成，在花器官发生过程中会发生变化，其成分主要由（）-β-法尼烯、（）-α-法尼烯或（+）-瓦伦烯主导。将微阵列探针重新映射到基因模型，以便对葡萄基因图谱中的表达模式进行荟萃分析，从而鉴定出可能调节花中萜类生物合成的基因。在三个品种中分离并对选定的倍半萜合酶基因进行了功能表征。与目标基因模型功能相关的基因型差异导致从亚历山大麝香葡萄花中分离出一种新的、品种特异性的单产物倍半萜合酶（VvivMATPS10），其主要挥发性产物为（）-β-法尼烯。此外，我们还鉴定了已表征基因中的结构变异（单核苷酸多态性、插入缺失和剪接变异），这些变异可能以品种特异性方式影响酶功能和/或挥发性倍半萜的产生。
