MADS-domain transcription factors can serve as stage-specific ‘master’ regulators of development programs. They often act in multimeric complexes along with 2 or more other MADS-domain factors. The MIKC* factors are primarily expressed in pollen and control a large number of pollen-expressed genes. The double mutant combination of agl66-1 and agl104-2 eliminates nearly all MIKC* activity. The mutant pollen is morphologically normal but the rate and frequency of germination is reduced and tube growth is slow. They don’t stand a chance if they are competing against wild type pollen!
See Adamczyk, B.J., and D.E. Fernandez (2009). MIKC* MADS-domain heterodimers are required for pollen maturation and tube growth in Arabidopsis. Plant Physiol. 149: 1713-1723.