Ascorbic acid (ASA) is an essential antioxidant, participating in diverse processes. In this study, tomato fruit at two maturity stages (mature-green, breaker) were first exposed to light at four photosynthetic photon flux density (PPFD) levels [0 (darkness), 50, 300, 600 μmol m-² s^-1], and then to darkness. As PPFD increased, ASA content was enhanced. The light-induced ASA content increase was dependent on the maturity stage, and persisted following darkening. High PPFD up-regulated the expression of key genes of the D-mannose/L-galactose pathway, showing the biosynthesis contributed, while the ASA recycling had a limited contribution. Weighted correlation network analysis showed that high PPFD potentially enhances the photosynthetic photon transduction, especially cyclic electron flow to excess photons. High PPFD up-regulated the expression of genes encoding non-enzymatic antioxidant biosynthesis. We show that photosynthetic photon transduction mediates fruit adaptation to light intensity, and provides new insights into the interactive regulation of fruit ASA accumulation.

抗坏血酸 (ASA) 是一种必不可少的抗氧化剂，参与多种过程。在这项研究中，番茄果实在两个成熟阶段（成熟-绿色、破碎）首先暴露在四个光合光子通量密度（PPFD）水平 [0（黑暗）、50、300、600 μmol m- ² s ^-1]，然后进入黑暗。随着 PPFD 增加，ASA 含量增加。光诱导的 ASA 含量增加取决于成熟阶段，并在变暗后持续存在。高 PPFD 上调 D-甘露糖/L-半乳糖途径关键基因的表达，表明生物合成有贡献，而 ASA 回收的贡献有限。加权相关网络分析表明，高 PPFD 可能会增强光合光子转导，尤其是循环电子流向过量光子。高 PPFD 上调编码非酶促抗氧化剂生物合成的基因的表达。我们表明光合光子转导介导水果对光强度的适应，并为水果 ASA 积累的交互调节提供了新的见解。