Abstract

In response to pine wood nematode (PWN) invasion, pine trees can activate immune responses involving effector-triggered signalling, leading to redox imbalance and programmed cell death. However, such hypersensitive responses are also implicated in disrupting water conduction and accelerating wilting. Despite the identification of several PWN effectors, their roles in modulating host immunity remain unclear. Using integrated transcriptomic and metabolomic analyses across PWN infection timepoints, we revealed that the jasmonate (JA) pathway played a central role in the induction of defence responses; the expression levels of genes involved in JA biosynthesis and signal transduction changed markedly at different stages of PWN invasion. Through yeast two-hybrid screening, we revealed that the PWN effector BxCDP1 interacts with PmTIFY8, a key transcriptional regulator of the Jasmonate ZIM-domain (JAZ) family in the JA signalling pathway. We further demonstrated that this interaction occurs in the nucleus, attenuates reactive oxygen species (ROS)-mediated cell death, and modulates the expression of JA-responsive genes. Our results indicate that the interaction of BxCDP1 with JAZ proteins can impede the JA-mediated immune responses, which is a key link of PWN pathogenicity and provides information for genetic improvement to enhance resistance in pine trees.