Research Institute for Viticulture and Oenology, University of Pécs, Pázmány P. u. 4, Pécs, 7634, Hungary.
Department of Plant Biology, University of Pécs, Ifjúság u. 6, Pécs, 7624, Hungary.
Sci Rep. 2020 Aug 28;10(1):14241. doi: 10.1038/s41598-020-70706-7.
Flavonols play key roles in many plant defense mechanisms, consequently they are frequently investigated as stress sensitive factors in relation to several oxidative processes. It is well known that grapevine (Vitis vinifera L.) can synthesize various flavonol glycosides in the leaves, however, very little information is available regarding their distribution along the cane at different leaf levels. In this work, taking into consideration of leaf position, the main flavonol glycosides of a red grapevine cultivar (Cabernet Sauvignon) were profiled and quantified by HPLC-DAD analysis. It was found that amount of four flavonol glycosides, namely, quercetin-3-O-galactoside, quercetin-3-O-glucoside, kaempferol-3-O-glucoside and kaempferol-3-O-glucuronide decreased towards the shoot tip. Since leaf age also decreases towards the shoot tip, the obtained results suggest that these compounds continuously formed by leaf aging, resulting in their accumulation in the older leaves. In contrast, quercetin-3-O-glucuronide (predominant form) and quercetin-3-O-rutinoside were not accumulated significantly by aging. We also pointed out that grapevine boosted the flavonol biosynthesis in September, and flavonol profile differed significantly in the two seasons. Our results contribute to the better understanding of the role of flavonols in the antioxidant defense system of grapevine.
类黄酮在许多植物防御机制中起着关键作用，因此它们经常被作为与几种氧化过程有关的应激敏感因子进行研究。众所周知，葡萄（Vitis vinifera L.）可以在叶片中合成各种类黄酮糖苷，然而，关于它们在不同叶位沿茎的分布情况，信息非常有限。在这项工作中，考虑到叶片位置，采用 HPLC-DAD 分析对一个红葡萄品种（赤霞珠）的主要类黄酮糖苷进行了分析和定量。结果发现，四种类黄酮糖苷（槲皮素-3-O-半乳糖苷、槲皮素-3-O-葡萄糖苷、山柰酚-3-O-葡萄糖苷和山柰酚-3-O-葡萄糖醛酸苷）的含量向梢端减少。由于叶片的年龄也向梢端减少，因此得出的结果表明，这些化合物随着叶片衰老而不断形成，导致它们在较老的叶片中积累。相反，随着叶片衰老，槲皮素-3-O-葡萄糖醛酸苷（主要形式）和槲皮素-3-O-芦丁苷没有明显积累。我们还指出，葡萄在 9 月促进了类黄酮的生物合成，两个季节的类黄酮谱有显著差异。我们的研究结果有助于更好地理解类黄酮在葡萄抗氧化防御系统中的作用。
