Probable transcription factor that forms a heterodimer with the MADS-box protein AGL30 and is involved in the regulation of pollen maturation at the late stages of pollen development and pollen tube growth. Forms a heterodimer with AGL30. Expressed in pollen. No visible phenotype under normal growth conditions. Pollen grains from the double mutant agl66 and agl104 have severely reduced viability, delayed germination and aberrant pollen tube growth. Extended C-terminus.