Trans-2-decenal inhibits Phytophthora capsici by inducing ROS accumulation and mitochondrial dysfunction

Phytophthora capsici is a highly destructive plant-pathogenic oomycete that poses a severe threat to global agricultural production. Trans-2-decenal is a natural plant-derived unsaturated aliphatic aldehyde, whose antimicrobial properties against plant pathogens remain poorly understood. In this study, its inhibitory efficacy and underlying mechanisms against P. capsici were systematically investigated. Trans-2-decenal exhibited potent inhibitory activity against P. capsici via biofumigation, with an EC₅₀ value of 12.37 μg/mL. It not only impacted normal hyphal morphology and ultrastructure, but also inhibited sporangia formation, zoospore release, and germination in a dose-dependent manner. Calcofluor white staining showed that trans-2-decenal disrupted cell wall integrity. Trans-2-decenal treatment compromised cell membrane integrity and permeability, accompanied by DNA and soluble protein leakage. Additionally, trans-2-decenal triggered intracellular ROS accumulation, reduced glutathione levels, and disrupted mitochondrial membrane potential, ultimately leading to cellular dysfunction and death. In planta assays validated its robust control efficacy against P. capsici infection. Transcriptomic analysis further identified 2557 differentially expressed genes, with significant downregulation in critical metabolic pathways such as nitrogen metabolism, tyrosine metabolism and phenylalanine metabolism. Taken together, these results elucidate a multitarget inhibitory mechanism of trans-2-decenal against P. capsici, and highlight its potential as an eco-friendly agent for the sustainable management of Phytophthora-induced plant diseases.