Catabolism of plant secondary metabolites can yield bioactive breakdown products. However, these compounds often remain poorly characterized. Here, we report on the discovery, biosynthesis, and biological relevance of 5 Methoxy-2-Nitrophenol (5M2NP), a secondary metabolite breakdown product which accumulates in damaged maize tissues. We used mutant plants, biochemical complementation, and metabolomic analyses to determine the biosynthetic origin of 5M2NP. Additionally, we assessed 5M2NP′s role in plant defense against herbivores. For this, we surveyed defense-associated responses (gene expression, phytohormones, volatile organic compounds) in wounded, 5M2NP-supplemented maize leaves, and performed bioassays with herbivorous insects. We found that 5M2NP accumulation upon tissue disruption is contingent upon a functional benzoxazinoid biosynthesis pathway. Labeling experiments demonstrated that 5M2NP is derived from DIMBOA. Physiological doses of exogenous 5M2NP increased the wound-induced expression of defense genes and emission of terpenoids. Additionally, 5M2NP exhibited antibiotic and antixenotic activities towards both generalist and specialist herbivores in nano- to micromolar quantities. We conclude that 5M2NP, which represents a novel class of plant-derived compounds, can act as a direct defense and a defense modulator. 5M2NP thus expands the functional repertoire of benzoxazinoids and likely contributes to their protective function against insect herbivores. The discovery of 5M2NP highlights the multifunctionality of plant secondary metabolites and their breakdown products.

中文翻译：

---

苯并恶嗪类分解产物 5-甲氧基-2-硝基苯酚在玉米防御草食害虫方面具有双重功能

植物次生代谢物的分解代谢可以产生具有生物活性的分解产物。然而，这些化合物的表征往往仍然很差。在这里，我们报告了 5 甲氧基-2-硝基苯酚 (5M2NP) 的发现、生物合成和生物学相关性，5M2NP 是一种在受损玉米组织中积累的次级代谢分解产物。我们使用突变植物、生化互补和代谢组学分析来确定 5M2NP 的生物合成来源。此外，我们还评估了 5M2NP 在植物防御食草动物中的作用。为此，我们调查了补充 5M2NP 的受伤玉米叶子中与防御相关的反应（基因表达、植物激素、挥发性有机化合物），并用草食性昆虫进行了生物测定。我们发现组织破坏时 5M2NP 的积累取决于功能性苯并恶嗪类生物合成途径。标记实验表明5M2NP源自DIMBOA。生理剂量的外源 5M2NP 增加了伤口诱导的防御基因表达和萜类化合物的排放。此外，5M2NP 对普通和专科食草动物表现出纳摩尔至微摩尔量的抗生素和抗异种活性。我们得出的结论是，5M2NP 代表了一类新型植物源化合物，可以充当直接防御和防御调节剂。因此，5M2NP 扩展了苯并恶嗪类化合物的功能库，并可能有助于其针对食草昆虫的保护功能。5M2NP的发现凸显了植物次生代谢产物及其分解产物的多功能性。