Effects of seed infection by Fusarium verticillioides on maize performance against Sesamia nonagrioides attack

In maize (Zea mays L), the fungus Fusarium verticillioides can behave as a pathogen, but it is also able of asymptomatic colonization as an endophyte. Therefore, it would be of great value to identify metabolites and/or metabolic pathways implicated in mutualistic and pathogenic interactions. The objectives of the present study were: (i) to investigate the effect of seed colonization by F. verticillioides on maize growth in a group of inbreds with contrasting resistance to F. verticillioides; (ii) to know if maize priming by Fusarium seed infection affects maize response to other parasites and if these differences could depend on genotype resistance to Fusarium; and (iii) to determine which metabolites could be associated to beneficial/detrimental changes on maize performance. Targeted and untargeted metabolomic approaches were carried out to characterize the response of control and primed plants to the most common maize pest in the Mediterranean area, Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae). The study cannot assume a differential pattern of infection between resistant and susceptible inbreds, but seed inoculation with F. verticillioides upon infestation with S. nonagrioides, significantly altered defense metabolism in resistant inbreds. Meanwhile it also induced a lipid response in susceptible inbreds that could mediate their increased plant susceptibility to insect attack. Although an endophytic interaction between the fungus and specific genotypes cannot be proven, defense pathways were favorably altered by F. verticillioides colonization among resistant inbreds.