Cloning and characterization of a HOG-type MAP kinase encoding gene from Fusarium proliferatum

Fphog1 , a HOG-type mitogen-activated protein kinase (MAPK) encoding gene of Fusarium proliferatum was constitutively expressed in all types of fungal cells. Δ Fphog1 mutants grew normally on artificial media; sporulation and spore germination were also normal. The mating capability of M24, a representative strain of the Δ Fphog1 mutants, showed no detectable decline, indicating that this HOG-type MAPK gene is dispensable for growth and reproduction under optimal culture conditions. Strain M24 had increased tolerance to vinclozoline and fludioxonil fungicides. Invasive growth of the wild type and three Δ Fphog1 gene replacement mutants (M21, M24, M36) were assessed on tomato fruits. All strains behaved similarly, i.e. they produced visible symptoms on the second day after infection, and produced ∼3 cm lesion, overgrown by fungal mycelium after six days of incubation. These data suggest that the HOG-type MAPK pathway is not required for the invasive growth of this fungus