Invisible Shields: Fungi Empower Trees

This article comments on: ‘Alliance Between Conifer Trees and Endophytic Fungi Against Insect Defoliators’. The article reveals that fungal endophytes play a crucial role in conifer defence against herbivores by producing toxic metabolites and volatile organic compounds (VOCs) that alter budworm behaviour and physiology, potentially reducing growth and fitness. Their study across 30 white spruce families shows that endophyte community composition, influenced by host genotype and environment, correlates with defensive metabolite profiles. Inoculation experiments further demonstrate that endophytes not only exert direct anti‐herbivore effects but also enhance host production of monoterpenes and sesquiterpenes. These findings support the ‘Plant Partnership (PP) Hypothesis’, suggesting a coevolutionary relationship among endophytes, plant defences, and herbivores. This study highlights endophytes as both biochemical defenders and modulators of host metabolism.