Overexpression of the maize 9-lipoxygenase gene <i>LOX4</i> confers resistance to <i>Fusarium verticillioides</i> via the oxylipin- and jasmonic acid-mediated pathways

Fusarium verticillioides is a widespread pathogen in cereals that reduces crop yields and poses a threat to food safety by producing the secondary metabolites fumonisins. Maize lipoxygenase genes (LOXs) are involved in the biosynthesis of oxylipins that function as signals in regulating defense. Previously, we showed that mutation of LOX4 is associated with susceptibility to Fusarium verticillioides in kernels, seedlings, and ears via alterations in both transcript profiles and LOX enzymatic activity. In this current study, we show that LOX4 overexpression results in enhanced resistance to pathogen infection and fumonisin contamination, substantiating its role in defense. Transcriptomic and lipidomic analyses revealed that LOX4 overexpression up-regulated expression of 9-LOX genes, thereby increasing the production of 9-oxylipin under fungal infection. The increased expression of jasmonic acid-related genes observed in infected plants was enhanced when LOX4 was overexpressed, correlating with wider accumulation of jasmonic acid-related metabolites. Our results indicate that LOX4 is a good target gene for future engineering of cultivars with increased resistance to F. verticillioides.