Transcription factor acting downstream of the MPS1 MAP kinase (MAPK) cascade during conidiation and plant infection (PubMed:18344407). Required for overcoming plant defense responses and the differentiation of secondary infectious hyphae in live plant cells (PubMed:18344407). Interacts with MAPK MPS1. Expressed in conidia but not in aerial hyphae or conidiophores. The MADS-box domain is essential for the function but dispensable for nuclear localization. Leads to reduced aerial hyphal growth and conidiation (PubMed:18344407). Does not affect appressorium formation but impairs infectious growth (PubMed:18344407). Belongs to the MEF2 family.