Davies Christopher, Shin Ryoung, Liu Weihong, Thomas Mark R, Schachtman Daniel P
CSIRO Plant Industry and Cooperative Research Centre for Viticulture, PO Box 350, Glen Osmond, SA 5064, Australia.
J Exp Bot. 2006;57(12):3209-16. doi: 10.1093/jxb/erl091. Epub 2006 Aug 25.
Potassium accumulation is essential for grapevine (Vitis vinifera L.) growth and development, but excessive levels in berries at harvest may reduce wine quality particularly for red wines. In addition to decreasing the free acid levels, potassium also combines with tartaric acid to form largely insoluble potassium bitartrate. This precipitates during winemaking and storage, resulting in an increase in wine pH that is associated with negative impacts on wine colour, flavour, and microbiological stability. For these reasons, a better understanding of potassium transport and accumulation within the vine and berries is important for producing fruit with improved winemaking characteristics. Here two genes encoding KUP/KT/HAK-type potassium transporters that are expressed in grape berries are described. Their function as potassium transporters was demonstrated by complementation of an Escherichia coli mutant. The two transporters are expressed most highly in the berry skin during the first phase of berry development (pre-veraison), with similar patterns in two grapevine varieties. The timing and location of expression of these transporters are consistent with an involvement in potassium accumulation in grape berries.
钾的积累对葡萄（Vitis vinifera L.）的生长发育至关重要，但收获时浆果中钾含量过高可能会降低葡萄酒品质，尤其是对于红葡萄酒。除了降低游离酸水平外，钾还会与酒石酸结合形成基本上不溶的酒石酸氢钾。这在酿酒和储存过程中会沉淀，导致葡萄酒pH值升高，这会对葡萄酒的颜色、风味和微生物稳定性产生负面影响。出于这些原因，更好地了解葡萄藤和浆果内钾的运输和积累对于生产具有改善酿酒特性的果实很重要。本文描述了两个在葡萄浆果中表达的编码KUP/KT/HAK型钾转运蛋白的基因。通过对大肠杆菌突变体的互补作用证明了它们作为钾转运蛋白的功能。这两种转运蛋白在浆果发育的第一阶段（转色前）在浆果表皮中表达最高，在两个葡萄品种中具有相似的模式。这些转运蛋白表达的时间和位置与参与葡萄浆果中钾的积累一致。
