Study of pathogenicity and determination of mating type of Fusarium proliferatum isolates

Fusarium proliferatum is the dominant agent of maize fusarium ear rot in many areas of the world especially in Iran. Among several Fusarium isolates recovered from infected maize ears, 12 isolates were identified as F. proliferatum according to morphological and physiological characteristics. In order to determine mating population and mating type of isolates, all 12 isolates were crossed with standard tester isolates of F. proliferatum on Carrot Agar (CA) media and were incubated under the mixture of cool-white and near-UV lights for three to four weeks. This test was repeated twice with three replications. Morphological identification of all isolates was confirmed by mating population test so that all 12 isolates of F. proliferatum belonged to mating population D of Gibberella fujikuroi complex. The results of mating type test showed that seven isolates were MAT-1 (58.3% frequency) and five isolates were MAT-2 (47.7% frequency). Pathogenicity test on stems of susceptible maize line (MO17) was done using toothpicks method in field, greenhouse and laboratory (Detached stem). The Pathogenicity of isolates was evaluated by measuring the necrosis length on inoculated stem. The results of variance analysis of pathogenicity tests showed significant differences among isolates in all mentioned methods. In field, greenhouse and laboratory trials, isolates SK27, SK32 and SK24 had the highest diseases severity (length necrosis), respectively. Significant and positive correlations were observed between field and greenhouse tests (r = 0.86**), field and  laboratory tests (r = 0.75**), and greenhouse and laboratory tests (r = 0.75**).