Abstract A common response of plant leaves and roots to stress, biotic or abiotic, is the oxidative burst. In leaves, this results in reactive oxygen species being produced within the apoplast, the space surrounding the responding cells. A second response that occurs in the tobacco apoplast during this period is the production and accumulation of phenolic metabolites. The interaction of these redox active metabolites should have major effects on the redox potential of the apoplast and subsequently affect the outcome of the plant tissue. To begin to understand the effects of these responses on the redox potential, two induced phenolics, acetovanillone (AV) and acetosyringone (AS) were studied in vitro with peroxidase and H2O2, all of which are present in the tobacco apoplast. While both phenolics were observed to be substrates for peroxidase, AV was found to react 10x faster than AS. The oxidation of AV resulted in an increase of the redox potential to a maximum of 0.35 V. The oxidation of AS resulted in an increase to a maximum of 0.55 V. Interestingly, the redox potential was not proportional to the oxidation of either phenolic. It was found that when present together, co-oxidation occurs with the faster acting AV as a catalyst to oxidize AS. This has an immediate effect on the redox potential. The rate of AS oxidation is dependent on the AV concentration and thus so is the redox potential reaching 4.5 V. The results suggest that these phenolics could play a role in the regulation of the apoplast redox potential during the early stages of stress.

中文翻译：

---

质外体氧化还原代谢：乙酰香草酮（夹竹桃素）和乙酰丁香酮对其共氧化和氧化还原特性的影响

摘要 植物叶和根对生物或非生物胁迫的常见反应是氧化爆发。在叶子中，这会导致在质外体（响应细胞周围的空间）内产生活性氧。在此期间烟草质外体中发生的第二个反应是酚类代谢物的产生和积累。这些氧化还原活性代谢物的相互作用应该对质外体的氧化还原电位产生重大影响，并随后影响植物组织的结果。为了开始了解这些反应对氧化还原电位的影响，使用过氧化物酶和 H2O2 在体外研究了两种诱导酚类物质，乙酰香草酮 (AV) 和乙酰丁香酮 (AS)，所有这些物质都存在于烟草质外体中。虽然观察到两种酚类物质都是过氧化物酶的底物，发现 AV 的反应速度比 AS 快 10 倍。AV 的氧化导致氧化还原电位增加到最大值 0.35 V。AS 的氧化导致增加到最大值 0.55 V。有趣的是，氧化还原电位与任一酚类的氧化都不成正比。发现当一起存在时，发生共氧化，同时作用较快的 AV 作为氧化 AS 的催化剂。这对氧化还原电位有直接影响。AS 氧化的速率取决于 AV 浓度，因此达到 4.5 V 的氧化还原电位也是如此。结果表明，这些酚类物质可以在应激的早期阶段调节质外体氧化还原电位。AS 的氧化导致增加到最大值 0.55 V。有趣的是，氧化还原电位与任一酚类的氧化都不成正比。发现当一起存在时，发生共氧化，同时作用较快的 AV 作为氧化 AS 的催化剂。这对氧化还原电位有直接影响。AS 氧化的速率取决于 AV 浓度，因此达到 4.5 V 的氧化还原电位也是如此。结果表明，这些酚类物质可以在应激的早期阶段调节质外体氧化还原电位。AS 的氧化导致增加到最大值 0.55 V。有趣的是，氧化还原电位与任一酚类的氧化都不成正比。发现当一起存在时，发生共氧化，同时作用较快的 AV 作为氧化 AS 的催化剂。这对氧化还原电位有直接影响。AS 氧化的速率取决于 AV 浓度，因此达到 4.5 V 的氧化还原电位也是如此。结果表明，这些酚类物质可以在应激的早期阶段调节质外体氧化还原电位。这对氧化还原电位有直接影响。AS 氧化的速率取决于 AV 浓度，因此达到 4.5 V 的氧化还原电位也是如此。结果表明，这些酚类物质可以在应激的早期阶段调节质外体氧化还原电位。这对氧化还原电位有直接影响。AS 氧化的速率取决于 AV 浓度，因此达到 4.5 V 的氧化还原电位也是如此。结果表明，这些酚类物质可以在应激的早期阶段调节质外体氧化还原电位。