The vacuolar channel VvALMT9 mediates malate and tartrate accumulation in berries of Vitis vinifera
The vacuolar channel VvALMT9 mediates malate and tartrate accumulation in berries of Vitis vinifera
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DOI：
10.1007/s00425-013-1888-y
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发表时间：
2013-08-01
期刊：
影响因子：
4.3
通讯作者：
Regalado, Ana
中科院分区：
文献类型：
--
作者：
De Angeli, Alexis;Baetz, Ulrike;Regalado, Ana
欧洲葡萄是一种重要的经济果树。葡萄和葡萄酒的味道是由一系列复杂的化合物组成的。浆果的酸度是决定葡萄浆果品质的主要参数，用于酿酒和水果消费。尽管苹果酸和酒石酸(TA)的储存和运输对葡萄浆果的酸度很重要，但到目前为止还没有发现苹果酸或酒石酸的液泡转运体。拟南芥的铝激活苹果酸转运体(ALMT)阴离子通道家族中的一些成员已被证明参与调节液泡膜上的苹果酸通量。因此，我们假设这些通道的同源物可能在葡萄浆果中具有类似的作用。我们通过在葡萄基因组数据库上进行TBLASTX搜索，鉴定了拟南芥液泡阴离子通道AtALMT9的同源物。我们从葡萄果实中克隆了与AtALMT9最接近的同源基因，命名为VvALMT9。表达谱显示VvALMT9在浆果中果皮组织中有结构性表达，并在果实成熟过程中转录水平升高。此外，我们还发现VvALMT9是针对液泡膜的。利用膜片钳分析，我们可以证明，除了苹果酸，VvALMT9介导的酒石酸电流高于其在拟南芥中的同源物。综上所述，在本研究中，我们提供了VvALMT9是一种在葡萄浆果中表达的液泡型苹果酸通道的证据。有趣的是，在产酒石酸盐的葡萄属植物中，通道的渗透性显然被调节为TA。
Vitis vinifera L. represents an economically important fruit species. Grape and wine flavour is made from a complex set of compounds. The acidity of berries is a major parameter in determining grape berry quality for wine making and fruit consumption. Despite the importance of malic and tartaric acid (TA) storage and transport for grape berry acidity, no vacuolar transporter for malate or tartrate has been identified so far. Some members of the aluminium-activated malate transporter (ALMT) anion channel family from Arabidopsis thaliana have been shown to be involved in mediating malate fluxes across the tonoplast. Therefore, we hypothesised that a homologue of these channels could have a similar role in V. vinifera grape berries. We identified homologues of the Arabidopsis vacuolar anion channel AtALMT9 through a TBLASTX search on the V. vinifera genome database. We cloned the closest homologue of AtALMT9 from grape berry cDNA and designated it VvALMT9. The expression profile revealed that VvALMT9 is constitutively expressed in berry mesocarp tissue and that its transcription level increases during fruit maturation. Moreover, we found that VvALMT9 is targeted to the vacuolar membrane. Using patch-clamp analysis, we could show that, besides malate, VvALMT9 mediates tartrate currents which are higher than in its Arabidopsis homologue. In summary, in the present study we provide evidence that VvALMT9 is a vacuolar malate channel expressed in grape berries. Interestingly, in V. vinifera, a tartrate-producing plant, the permeability of the channel is apparently adjusted to TA.