AlTPS6 from Atractylodes lancea Is a Crucial Regulatory Target for Root-Knot Nematode Infestation.

Root-knot nematodes (RKNs) are widespread parasites that damage crops by weakening the plant immune system, causing root galls and stunting growth. However, the molecular mechanisms behind how RKNs regulate host plant defenses remain largely unknown. The medicinal plant Atractylodes lancea frequently suffers losses from RKNs. We investigated the alterations in A. lancea pre- and postinfection by Meloidogyne hapla utilizing histological, transcriptomic, and metabolomic assessment. Infected roots exhibited compromised tissue and giant cell formation as well as a notable reduction of essential oils and four typical bioactive components, i.e., β-eudesmol, hinesol, atractylon, and atractylodin. Transcriptomic analysis revealed significant changes in gene expression related to the cell wall, MAPK pathway, heat shock proteins, peroxidases, ubiquitin proteases, TFs, TPS, and hormones. The AlTPS6 gene was identified as responsible for producing β-caryophyllene, which exhibited strong attraction at low concentrations and nematicidal activity at high concentrations. Taken together, M. hapla downregulated AlTPS6 expression by manipulating host MAPK signaling and related genes to succeed in their infection and reproduction in A. lancea. Our results broaden our insight into the interaction and regulation between RKNs and host.