Transcriptomic and metabolomic analysis revealed the herbicidal mechanisms of root-derived allelochemicals from Quercus mongolica against weeds.

Abstract

Plant allelochemicals have attracted increasing attention as environmental herbicides for weed management. However, the herbicidal mechanisms of plant-derived allelochemicals remain insufficiently explored. In this study, Quercus mongolica plantation was found to possess extremely sparse understory vegetation, and its root extracts exhibited broad-spectrum inhibitory effects against five common weeds. Phytochemical analysis identified fifteen compounds as potential herbicidal constituents in Q. mongolica root extracts. Portulaca oleracea, which showed the highest suppression to the extracts (inhibition rate of 68.92% at a concentration of 1mg/mL), was therefore selected as a representative weed for mechanistic analysis. The dose-response analysis indicates that the extracts at a concentration of 2mg/mL are able to effectively inhibit seedling growth. Microscopic observations revealed pronounced root browning, cell wall disruption, and leaf deformation in extract-treated P. oleracea seedlings. Meanwhile, the oxidative stress was observed in extract-treated P. oleracea seedlings. In addition, transcriptomic analysis indicated significant downregulation of nine photosynthesis-related genes, suggesting disruption of photosynthetic electron transport and the Calvin cycle, thereby inhibiting seedling growth. Metabolomic analysis further showed the accumulation of metabolites associated with the phenylpropanoid pathway in seedlings following extract-induced damage. In summary, Q. mongolica root extracts may represent a potential natural source for further development of botanical herbicides.

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