Sugars act as signaling molecules to modulate various growth processes and enhance plant tolerance to various abiotic and biotic stresses. Moreover, sugars contribute to the post-harvest flavor in fleshy fruit crops. To date, the regulation of sugar metabolism and its effect in plant growth, fruit ripening, postharvest quality and stress resistance remains not fully understood. In this study, we investigated the role of tomato gene encoding a vacuolar invertase, hydrolyzing sucrose to glucose and fructose. SlVI is specifically expressed during the tomato fruit ripening process. We found that overexpression of SlVI resulted in increased leaf size and early flowering, while knockout of SlVI led to increased fruit sucrose content, enhanced fruit firmness, and elevated resistance of postharvest fruit to Botrytis cinerea. Moreover, the content of naringenin and total soluble solids was significantly increased in SlVI knockout fruit at postharvest stage. Transcriptome analysis showed a negative feedback regulation triggered by sucrose accumulation in SlVI knockout fruit resulting in a downregulation of BAM3 and AMY2, which are critical for starch degradation. Moreover, genes associated with cell wall, cutin, wax, and flavonoid biosynthesis and pathogen resistance were upregulated in SlVI knockout fruit. Conversely, the expression levels of genes involved in cell wall degradation were decreased in knockout fruit. These results are consistent with the enhanced postharvest quality and resistance. Our findings not only provide new insights into the relationship between tomato fruit sucrose content and postharvest fruit quality, but also suggest new strategies to enhance fruit quality and extend postharvest shelf life.

中文翻译：

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液泡转化酶基因 SlVI 调节番茄糖代谢、采后果实品质和抗逆性


糖作为信号分子调节各种生长过程并增强植物对各种非生物和生物胁迫的耐受性。此外，糖有助于肉质水果作物收获后的风味。迄今为止，糖代谢的调节及其对植物生长、果实成熟、采后品质和抗逆性的影响仍不完全清楚。在这项研究中，我们研究了编码液泡转化酶的番茄基因的作用，该酶将蔗糖水解为葡萄糖和果糖。 SlVI 在番茄果实成熟过程中特异性表达。我们发现SlVI的过度表达导致叶片尺寸增大和提前开花，而SlVI的敲除导致果实蔗糖含量增加、果实硬度增强以及采后果实对灰霉病菌的抗性增强。此外，SlVI敲除果实在采后阶段柚皮素和总可溶性固形物的含量显着增加。转录组分析显示，SlVI 敲除果实中蔗糖积累引发负反馈调节，导致 BAM3 和 AMY2 下调，而 BAM3 和 AMY2 对淀粉降解至关重要。此外，与细胞壁、角质、蜡和类黄酮生物合成以及病原体抗性相关的基因在SlVI敲除果实中上调。相反，在基因敲除的果实中，参与细胞壁降解的基因的表达水平降低。这些结果与采后品质和抗性的增强是一致的。我们的研究结果不仅为番茄果实蔗糖含量与采后果实品质之间的关系提供了新的见解，而且还提出了提高果实品质和延长采后保质期的新策略。