Interspecific allelopathy suppresses potato cyst nematodes by 1-decanol derived from Houttuyniacordata.

Potato cyst nematodes (PCNs), Globodera rostochiensis, are an important group of quarantine plant-parasitic nematodes that pose a serious threat to the potato industry and global food security due to the lack of effective control measures. In this study, intercropping with Houttuynia cordata is shown to effectively reduce PCN populations while increasing potato yield. This effect is associated with the release of a key allelopathic volatile compound, 1-decanol, which exhibits strong nematicidal activity (LC50 = 31.5 μg/mL) markedly exceeding that of the commercial nematicide avermectin (LC50 = 63.8 μg/mL). Meanwhile, root irrigation with 1-decanol significantly reduces PCN infection in potato. Mechanistically, 1-decanol directly damages nematode surface structures, induces cellular apoptosis, and disrupts the oxidative stress regulation system, while also downregulating defense-related metabolic pathways in potato, thereby promoting the reallocation of metabolic resources from defense to growth. Moreover, 1-decanol does not alter the overall diversity of the rhizosphere microbial community but selectively reduces the abundance of pathogenic taxa, such as Fusarium while recruiting beneficial microbiota to the potato rhizosphere, thereby limiting synergistic infections by pathogens and nematodes. These data suggest that intercropping with H. cordata suppresses PCNs and enhances potato yield through the antimicrobial activity of its allelochemicals and their effects on nematodes, the rhizosphere microbiome, and host physiology. Ultimately, intercropping with H. cordata provides a sustainable strategy for PCN management.