The root endophytic fungus Trichoderma atroviride induces foliar herbivory resistance in maize plants

Plant roots naturally associate with Trichoderma spp., which can promote plant health and nutrition. Despite that Trichoderma spp. are well-known biocontrol agents, information on their effects against foliar insect herbivory is limited. Here, we examined the effects of T. atroviride in providing maize (Zea mays) resistance against the insect herbivore Spodoptera frugiperda. Increased plant growth, reduced herbivory and altered insect feeding pattern were observed after maize inoculation with T. atroviride. Plant protection was correlated with increased emission of volatile terpenes and accumulation of jasmonic acid, an activator of defense responses against herbivory. Chemical analyses revealed that T. atroviride produced the volatiles 1-octen-3-ol and 6-pentyl-2H-pyran-2-one. Pharmacological tests showed that both compounds reduced the consumption of foliar tissue and altered the feeding pattern of S. frugiperda in a similar way to T. atroviride. These results provide new insight into the role of T. atroviride in plant health in terms of induction of resistance to insect herbivory and production of antifeedant secondary metabolites.