Transcription activator. Binds to 5'-CAACTGTC-3' and/or 5'-TAACAAA-3' motif in target gene promoter to promote their expression. Together with MYB101 and MYB120, functions as a male factor that controls pollen tube-synergid interaction in fertilization. Required for pollen tube growth arrest and sperm cell release in the female gametophyte, probably via the regulation of pollen tube-specific gene expression