Pathocycles: Ustilago maydis as a model to study the relationships between cell cycle and virulence in pathogenic fungi.

Activation of virulence in pathogenic fungi often involves differentiation processes that need the reset of the cell cycle and induction of a new morphogenetic program. Therefore, the fungal capability to modify its cell cycle constitutes an important determinant in carrying out a successful infection. The dimorphic fungus Ustilago maydis is the causative agent of corn smut disease and has lately become a highly attractive model in addressing fundamental questions about development in pathogenic fungi.

Histone deacetylase Hda1 acts as repressor of the Ustilago maydis biotrophic marker gene mig1.

The Ustilago maydis mig1 gene is extensively up-regulated during growth within its host plant. A genetic approach was set up to identify mutants expressing mig1 during axenic growth. Five independent mutants were identified that not only displayed increased transcript levels of mig1 but also of egl1, an endoglucanase expressed in dikaryotic filaments.