Evaluation of resistance and the role of some defense responses in wheat cultivars to Fusarium head blight

Fusarium graminearum and F. culmorum are the causal agents of Fusarium head blight (FHB) in cereal crops worldwide. Application of resistant cultivars is the most effective and economic method for management of FHB and reducing mycotoxin production in wheat. Understanding the physiological and biochemical mechanisms involved in basal resistance of wheat to FHB disease is limited. In this research, after screening resistance levels of eighteen wheat cultivars planted in Iran, Gaskozhen and Falat were identified as partially resistant and susceptible wheat cultivars against Fusarium spp., respectively. Also, we investigated the role of hydroxyl radical (OH−), nitric oxide (NO), callose deposition, lipid peroxidation and protein content in basal resistance of wheat to the hemi-biotrophic and necrotrophic Fusarium species causing FHB. Nitric oxide as a signaling molecule may be involved in physiological and defensive processes in plants. Our results showed that NO generation increased in seedlings and spikes of wheat cultivars after inoculation with Fusarium species. We observed earlier and stronger callose deposition at early time points after infection by Fusarium spp. isolates than in non-infected plants, which was positively related to the resistance levels in wheat cultivars. Higher levels of OH− and malondialdehyde (MDA) accumulation (as a marker of lipid peroxidation) were observed in the Falat than in the Gaskozhen cultivar, under non-infected and infected conditions. So, estimation of lipid peroxidation could be useful to evaluate cultivars’ susceptibility. These findings can provide novel insights for better recognition of physiological and biochemical markers of FHB resistance, which could be used for rapid screening of resistance levels in wheat cultivars against this destructive fungal disease.