Plants, though sessile, employ various strategies to defend themselves against herbivorous insects. The production of terpenoids, and formation of symbiotic associations with arbuscular mycorrhizal fungi (AM) are two such defensive strategies.

Terpenoids deter herbivores, attract their predators and serve as airborne signals that induce defence responses in neighbouring uninfested plants. Sharma et al. show that AM affect the concentration and composition of terpenoids, boosting defence against herbivores. Hyphal networks in soil serve as conduits facilitating the transfer of defence signals and terpenoids between plants. Improved understanding of terpenoids and AM in plant defence will have significant implications for sustainable pest management in agricultural ecosystems.
This paper is part of the Annals of Botany Special Issue on Plant Immunity. It will be free access till June 2017 and after April 2018.