Zhang Xinsheng, Feng Chaoyang, Wang Manning, Li Tianlai, Liu Xin, Jiang Jing
College of Horticulture, Shenyang Agricultural University, 110866, Shenyang, Liaoning, China.
Key Laboratory of Protected Horticulture of Education Ministry, 110866, Shenyang, Liaoning, China.
Hortic Res. 2021 Aug 1;8(1):186. doi: 10.1038/s41438-021-00624-w.
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.
糖类，尤其是葡萄糖和果糖，对番茄果实的口感和品质有影响。这些化合物从叶片转运至果实，然后通过质膜上的各种糖转运蛋白卸载到果实中。SWEETs是一类能独立于能量或pH调节糖外排的糖转运蛋白。迄今为止，SWEETs在番茄中的作用很少受到关注。在本研究中，我们对SlSWEET7a和SlSWEET14进行了功能分析，以深入了解番茄果实中糖运输和储存的调控机制。SlSWEET7a和SlSWEET14主要在果梗、维管束和种子中表达。SlSWEET7a和SlSWEET14都是定位在质膜上的蛋白，可转运果糖、葡萄糖和蔗糖。除了使成熟果实的糖含量增加外，沉默SlSWEET7a或SlSWEET14还导致植株更高、果实更大（在沉默SlSWEET7a的株系中）。我们还发现一些SlSWEET成员的转化酶活性和基因表达增加，这与果实中蔗糖和己糖可用性的增加一致。总体而言，我们的结果表明，抑制SlSWEET7a和SlSWEET14可能是提高番茄果实糖含量的一种潜在策略。
