In strawberry, sucrose is the major form of carbohydrate translocated from the leaves to the fruits and plays an important role in fruit ripening. As a conserved energy sensor, sucrose nonfermenting-1 (SNF1)-related kinase 1 (SnRK1) plays an important role in plant carbon metabolism. However, evidence that SnRK1 regulates sucrose accumulation in fruits is lacking. In this study, we transiently expressed FaSnRK1α in strawberry fruits and found that overexpression (OE) of the FaSnRK1α gene significantly increased the sucrose content, whereas repression of FaSnRK1α by RNA interference (RNAi) decreased the sucrose content. Further analysis revealed that FaSnRK1α increased the expression of FaSUS1 and FaSUS3 as well as the activity of sucrose synthase (SUS; EC 2.4.1.13) and that FaSPS1 expression and sucrose phosphate synthase (SPS; EC 2.4.1.14) activity were strongly downregulated, which decreased the accumulation of sucrose. However, the expression of FaSPS3, which is reported to contribute to sucrose accumulation, was induced by FaSnRK1α, and FaNI expression and invertase (INV; EC 3.2.1.26) activity were upregulated by FaSnRK1α. In addition, FaSnRK1α positively upregulated the expression of the sucrose transporter (SUT) genes FaSUT1 and FaSUT5 and interacted with FaSUS1, FaSPS1 and FaSPS3 proteins but not with FaSUS3, FaNI, FaSUT1 or FaSUT5 proteins. Overall, FaSnRK1α systematically regulates the expression of the genes and activities of key enzymes involved in the sucrose metabolic pathway and promotes the long-distance transport of sucrose, thereby increasing sucrose accumulation and ultimately promoting fruit ripening. However, the mechanisms by which sucrose transport and degradation are regulated by SnRK1 warrant additional research.

中文翻译：

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蛋白激酶FaSnRK1α调节草莓果实中的蔗糖积累。

在草莓中，蔗糖是碳水化合物从叶子转移到果实的主要形式，并且在果实成熟中起重要作用。蔗糖非发酵-1（SNF1）相关激酶1（SnRK1）作为一种保守的能量传感器，在植物碳代谢中起着重要的作用。但是，缺乏SnRK1调节水果中蔗糖积累的证据。在这项研究中，我们在草莓果实中瞬时表达FaSnRK1α，发现FaSnRK1α基因的过表达（OE）显着增加了蔗糖含量，而通过RNA干扰（RNAi）抑制FaSnRK1α降低了蔗糖含量。进一步的分析表明，FaSnRK1α增加了FaSUS1和FaSUS3的表达以及蔗糖合酶（SUS； EC 2.4.1.13）的活性； FaSPS1表达和蔗糖磷酸合酶（SPS； EC 2.4.1）。14）活性被强烈下调，这降低了蔗糖的积累。然而，据报道促成蔗糖积累的FaSPS3的表达被FaSnRK1α诱导，而FaNI的表达和转化酶（INV； EC 3.2.1.26）活性被FaSnRK1α上调。此外，FaSnRK1α积极上调了蔗糖转运蛋白（SUT）基因FaSUT1和FaSUT5的表达，并与FaSUS1，FaSPS1和FaSPS3蛋白相互作用，但与FaSUS3，FaNI，FaSUT1或FaSUT5蛋白没有相互作用。总体而言，FaSnRK1α系统调节蔗糖代谢途径中涉及的关键酶基因的表达和活性，并促进蔗糖的长距离运输，从而增加了蔗糖的积累并最终促进了果实的成熟。然而，