Beneficial worm allies warn plants of parasite attack belowground and reduce aboveground herbivore preference and performance

We investigated responses of tomato (Solanum lycopersicum) to two functional guilds of nematodes - plant parasite (Meloidogyne javanica) and entomopathogens (Heterorhabditis bacteriophora, Steinernema feltiae belowground, and S. carpocapsae) - as well as a leaf mining insect (Tuta absoluta) aboveground. Our results indicate that entomopathogenic nematodes (EPNs): 1) induced plant defense responses, 2) reduced root knot nematode (RKN) infestation belowground and 3) reduced herbivore (T. absoluta) host preference and performance aboveground. Concurrently, we investigated the plant signaling mechanisms underlying these interactions using biochemical and transcriptome analyses. We found that both entomopathogen and parasite triggered immune responses in plant roots with shared gene expression. Tomato plants responded similarly to presence of RKN or EPN in the rootzone, by rapidly activating polyphenol oxidase (PPO) and guaiacol peroxidase (GP) activity in roots, but simultaneously suppresse...