Sugars, especially glucose and fructose, contribute to the taste and quality of tomato fruits. These compounds are translocated from the leaves to the fruits and then unloaded into the fruits by various sugar transporters at the plasma membrane. SWEETs, are sugar transporters that regulate sugar efflux independently of energy or pH. To date, the role of SWEETs in tomato has received very little attention. In this study, we performed functional analysis of SlSWEET7a and SlSWEET14 to gain insight into the regulation of sugar transport and storage in tomato fruits. SlSWEET7a and SlSWEET14 were mainly expressed in peduncles, vascular bundles, and seeds. Both SlSWEET7a and SlSWEET14 are plasma membrane-localized proteins that transport fructose, glucose, and sucrose. Apart from the resulting increase in mature fruit sugar content, silencing SlSWEET7a or SlSWEET14 resulted in taller plants and larger fruits (in SlSWEET7a-silenced lines). We also found that invertase activity and gene expression of some SlSWEET members increased, which was consistent with the increased availability of sucrose and hexose in the fruits. Overall, our results demonstrate that suppressing SlSWEET7a and SlSWEET14 could be a potential strategy for enhancing the sugar content of tomato fruits.

中文翻译：

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质膜定位的 SlSWEET7a 和 SlSWEET14 调节番茄果实中的糖转运和储存


糖，尤其是葡萄糖和果糖，有助于改善番茄果实的味道和品质。这些化合物从叶子转移到果实，然后通过质膜上的各种糖转运蛋白卸载到果实中。 SWEET 是糖转运蛋白，可独立于能量或 pH 值调节糖流出。迄今为止，甜食在番茄中的作用还很少受到关注。在这项研究中，我们进行了功能分析甜甜7a和甜甜14深入了解番茄果实中糖运输和储存的调节。甜甜7a和甜甜14主要表达于花序梗、维管束和种子中。 SlSWEET7a 和 SlSWEET14 都是质膜定位蛋白，可转运果糖、葡萄糖和蔗糖。除了导致成熟果实糖含量增加外，沉默甜甜7a或者甜甜14导致更高的植物和更大的果实（在甜甜7a - 静音线）。我们还发现转化酶活性和一些基因表达甜甜的成员增加，这与水果中蔗糖和己糖的可用性增加一致。总的来说，我们的结果表明，抑制甜甜7a和甜甜14可能是提高番茄果实糖含量的潜在策略。