Overexpression of the maize 9-lipoxygenase gene ZmLOX4 confers resistance to Fusarium verticillioides via the oxylipin and jasmonic acid-mediated pathways.

Fusarium verticillioides is a prominent pathogen in cereals that reduces crop yields and poses a threat to food safety by producing the secondary metabolites fumonisins. Maize lipoxygenases (ZmLOXs) genes are involved in the biosynthesis of oxylipins that function as signals in regulating defense. Previously, we showed that ZmLOX4 gene mutagenesis was associated with susceptibility to F. verticillioides in kernels, seedlings and ears altering ZmLOX transcript profiles as well as LOX enzymatic activity. In the current study, we show that ZmLOX4 overexpression results in enhanced pathogen and fumonisin contamination resistance, substantiating its role in defense and making ZmLOX4 a good target to confer disease resistance. Transcriptomic and lipidomic analyses reveal that ZmLOX4 overexpression up-regulates 9-LOX gene expression and boosts the 9-oxylipin production under fungal infection. The increased expression of jasmonic acid-related genes is also observed, but is reinforced when ZmLOX4 is overexpressed, correlating with wider accumulation of jasmonic acid-related metabolites. The ZmLOX4 gene has potential applications in engineering cropping plants to increase immunity to F. verticillioides.