Expression analysis and biochemical studies of defense-related genes in the pathosystem Fusarium verticilliodes-maize

Fusarium ear rot leads to mycotoxin contamination of kernels and loss of yield. We tested in six maize genotypes with contrasting levels of resistance to Fusarium verticillioides, genes involved in defense response. At 15 days after anthesis, on caryopses harvested 72 hours after infection, the expression of PR1, PR5, PRm3, PRm6, peroxidase, catalase 2, ascorbate peroxidase and superoxide dismutase 2, was evaluated. The level of induction was stronger in susceptible lines, followed by intermediate lines, while resistant lines responded with lower fold changes values. The trend of expression of the genes matched with the absolute quantification of the fungus beta-tubulin, indicating a higher copy number of the gene in susceptible genotypes, than resistant ones. Parallel, the activity of enzymes catalase, ascorbate peroxidase, generic peroxidases, superoxide dismutase, was determined to verify their effectiveness and involvement level in Fusarium verticillioides-maize pathosystem. In addition, the redox state of ascorbate and protein thiols as well the hydrogen peroxide and malondyaldheide contents were determined to evaluate the oxidation level in maize caryopses after infection.