Université de Bordeaux, ISVV, Ecophysiologie et Génomique Fonctionnelle de la Vigne, UMR 1287, F-33140 Villenave d'Ornon, France.
Plant Cell Physiol. 2012 Oct;53(10):1776-92. doi: 10.1093/pcp/pcs121. Epub 2012 Sep 5.
Among various environmental factors, temperature is a major regulator affecting plant growth, development and fruit composition. Grapevine is the most cultivated fruit plant throughout the world, and grapes are used for wine production and human consumption. The molecular mechanisms involved in grapevine tolerance to high temperature, especially at the fruit level, are poorly understood. To better characterize the sensitivity of berries to the microenvironment, high temperature conditions were locally applied to Vitis vinifera Cabernet Sauvignon clusters. Two genes, VvGOLS1 and VvHsfA2, up-regulated by this treatment, were identified and further characterized. The expression profile of VvGOLS1 correlated positively with galactinol accumulation in heat-stressed berries. However, no galactinol derivatives, such as raffinose and stachyose, accumulated upon heat stress. Heterologous expression of VvGOLS1 in Escherichia coli showed that it encodes a functional galactinol synthase. Transient expression assays showed that the heat stress factor VvHsfA2 transactivates the promoter of VvGOLS1 in a heat stress-dependent manner. Taken together, our results highlight the intrinsic capacity of grape berries to perceive heat stress and to initiate adaptive responses, suggesting that galactinol may play a signaling role in these responses.
在各种环境因素中，温度是影响植物生长、发育和果实组成的主要调节因素。葡萄是全球种植最广泛的水果植物，葡萄用于酿酒和人类消费。葡萄对高温的耐受性的分子机制，特别是在果实水平上，还知之甚少。为了更好地描述浆果对微环境的敏感性，对酿酒葡萄赤霞珠（Vitis vinifera Cabernet Sauvignon）的果穗进行了局部高温处理。鉴定并进一步表征了受该处理上调的两个基因 VvGOLS1 和 VvHsfA2。VvGOLS1 的表达谱与受热浆果中半乳糖醇的积累呈正相关。然而，在热胁迫下没有半乳糖醇衍生物（如棉子糖和水苏糖）积累。VvGOLS1 在大肠杆菌中的异源表达表明它编码一种功能性半乳糖醇合酶。瞬时表达试验表明，热胁迫因子 VvHsfA2 以热应激依赖的方式反式激活 VvGOLS1 的启动子。总之，我们的研究结果突出了葡萄浆果感知热应激和启动适应性反应的内在能力，表明半乳糖醇可能在这些反应中发挥信号作用。
