Sucrose metabolism is a fundamental process during tomato ripening. Studies have shown the role of the phytohormone methyl jasmonate (MeJA) in tomato fruit ripening. However, the role of MeJA in regulating sucrose metabolism in tomato is still unclear. In this study, mature green cherry tomato fruit were infiltrated with MeJA (0.5 mM) or sterile deionized water (control). The changes in color, firmness, and ethylene production in fruit, the contents of sucrose, glucose and fructose, and the enzymatic activities and the expression levels of key genes associated with sucrose metabolism were determined periodically during a storage period of 16 d. MeJA-treated fruit showed a significant acceleration in ripening, with higher a* value and ethylene production and lower firmness. MeJA treatment enhanced sucrose phosphate synthase (SPS) activity, whereas it inhibited acid invertase (AI) and neutral invertase (NI) activities. These changes in enzyme activities together resulted in a significantly higher sucrose content and lower glucose and fructose contents. Furthermore, exogenous MeJA upregulated the gene expression levels of sucrose-phosphate synthase1–4 (SPS1-4) and sucrose-phosphate phosphatase2 (SPP2), which were associated with sucrose biosynthesis, and downregulated those related to sucrose degradation, except for sucrose synthase2 (SUS2) and SUS3. The findings indicated that exogenous MeJA might alter sucrose metabolism during tomato ripening by regulating the enzymatic activities and gene expression levels. This research provides valuable information to elucidate the mechanisms via which MeJA regulates tomato sucrose metabolism.

蔗糖代谢是番茄成熟过程中的一个基本过程。研究表明植物激素茉莉酸甲酯 (MeJA) 在番茄果实成熟中的作用。然而，MeJA 在调节番茄蔗糖代谢中的作用尚不清楚。在这项研究中，成熟的绿色樱桃番茄果实被 MeJA (0.5 mM) 或无菌去离子水（对照）渗透。在16 d的贮藏期内定期测定果实颜色、硬度、乙烯产量、蔗糖、葡萄糖和果糖含量的变化，以及与蔗糖代谢相关的关键基因的酶活性和表达水平。MeJA 处理的果实在成熟方面表现出显着加速，具有更高的 a* 值和乙烯产量以及更低的硬度。MeJA 处理增强了蔗糖磷酸合酶 (SPS) 活性，而它抑制酸性转化酶 (AI) 和中性转化酶 (NI) 的活性。酶活性的这些变化共同导致显着更高的蔗糖含量和更低的葡萄糖和果糖含量。此外，外源性 MeJA 上调了蔗糖磷酸合酶 1-4 的基因表达水平（SPS1 - 4）和蔗糖磷酸phosphatase2（SPP2），这与蔗糖生物合成相关联，并且下调那些与蔗糖的分解，除了蔗糖synthase2（SUS2）和SUS3。研究结果表明，外源性 MeJA 可能通过调节酶活性和基因表达水平来改变番茄成熟过程中的蔗糖代谢。这项研究为阐明 MeJA 调节番茄蔗糖代谢的机制提供了宝贵的信息。