The oxidant/antioxidant balance affects the ripening time of tomato fruit. Ripening of tomato fruit is associated with several modifications such as loss of cell wall firmness and transformation of chloroplasts to chromoplasts. Besides a peak in H2O2, reactive oxygen species (ROS) are observed at the transition stage. However, the role of different components of oxidative stress metabolism in fruit ripening has been scarcely addressed. Two GDP-l-galactose phosphorylase (GGP) Solanum lycopersicum L. cv Micro-Tom mutants which have fruit with low ascorbic acid content (30% of wild type) were used in this work to unravel the participation of ascorbic acid and H2O2 in fruit maturation. Both GGP mutants show delayed fruit maturation with no peak of H2O2; treatment with ascorbic acid increases its own concentration and accelerates ripening only in mutants to become like wild type plants. Unexpectedly, the treatment with ascorbic acid increases H2O2 synthesis in both mutants resembling what is observed in wild type fruit. Exogenous supplementation with H2O2 decreases its own synthesis delaying fruit maturation in plants with low ascorbic acid content. The site of ROS production is localized in the chloroplasts of fruit of all genotypes as determined by confocal microscopy analysis. The results presented here demonstrate that both ascorbic acid and H2O2 actively participate in tomato fruit ripening.

中文翻译：

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低抗坏血酸含量对番茄果实成熟的影响

氧化剂/抗氧化剂平衡影响番茄果实的成熟时间。番茄果实的成熟与一些改变有关，例如细胞壁硬度的丧失和叶绿体向有色体的转化。除了 H2O2 的峰值外，在过渡阶段还观察到活性氧 (ROS)。然而，氧化应激代谢的不同成分在果实成熟中的作用几乎没有得到解决。在这项工作中使用了两种 GDP-l-半乳糖磷酸化酶 (GGP) Solanum lycopersicum L. cv Micro-Tom 突变体，其果实中抗坏血酸含量低（野生型的 30%），以揭示抗坏血酸和 H2O2 在果实中的作用成熟。两种 GGP 突变体均显示延迟果实成熟，没有 H2O2 峰值；用抗坏血酸处理会增加其自身的浓度，并仅在突变体中加速成熟，使其变得像野生型植物。出乎意料的是，抗坏血酸处理增加了两种突变体中 H2O2 的合成，类似于在野生型水果中观察到的情况。在抗坏血酸含量低的植物中，外源补充 H2O2 会降低其自身的合成，从而延缓果实成熟。如通过共聚焦显微镜分析所确定的，ROS产生的位点位于所有基因型的果实的叶绿体中。这里提供的结果表明，抗坏血酸和 H2O2 都积极参与番茄果实成熟。在抗坏血酸含量低的植物中，外源补充 H2O2 会降低其自身的合成，从而延缓果实成熟。如通过共聚焦显微镜分析所确定的，ROS产生的位点位于所有基因型的果实的叶绿体中。这里提供的结果表明，抗坏血酸和 H2O2 都积极参与番茄果实成熟。在抗坏血酸含量低的植物中，外源补充 H2O2 会降低其自身的合成，从而延缓果实成熟。如通过共聚焦显微镜分析所确定的，ROS产生的位点位于所有基因型的果实的叶绿体中。这里提供的结果表明，抗坏血酸和 H2O2 都积极参与番茄果实成熟。