Differential activation of defence genes and enzymes in mayze genotypes with contrasting levels of resistance to Fusarium verticillioides

We attempt to identify genes involved in Fusarium ear rot resistance using resistant and susceptible maize genotypes. Gene expression data were obtained from microarray hybridizations using seeds inoculated at 15 days after silking. At 48 hours after infection, differentially expressed sequences were identified and classified into 11 functional categories, principally assigned to the category cell rescue, defence and virulence in both lines. These genes encode for PR proteins, detoxification enzymes and beta-glucosidases. The differentialy expressed genes were validated in qPCR, also performed in silks 12, 24, 48 and 72 h after F. verticillioides infection. Parallel, we have studied the detoxifying enzymes ascorbate peroxidase (APX), catalase (CAT), total peroxidase (POD) and superoxide dismutase (SOD) in seedlings, before and at five days after F. verticillioides infection. In resistant seedlings, before infection, the defence genes, APX and SOD enzymatic activities were higher than in the susceptible ones while, after treatment, they remained unchanged. On the other hand, in susceptible seedlings, except for SOD, all enzymes and defence genes were activated by the pathogen.