Any of a superfamily of genes that encode transcription factors having crucial roles in the development of plants, animals, and fungi. The transcription factors are characterized by the MADS box, a sequence of about 56 amino acids that forms part of a DNA-binding domain of the protein. The acronym refers to the founding members of the family: MCM1 (from yeast), AGAMOUS and DEFICIENS (from flowering plants), and SRF (serum response factor, from mammals). Gymnosperms, angiosperms, ferns, and mosses all have numerous MADS box genes, which encode proteins involved in ensuring the correct timing and sequence of plant development, including determination of floral organ identity. Some act as homeotic genes, analogous to the Hox genes of animals, with mutations causing the transformation of one flower part into another (see abc model). Many of these aspects, such as timing of flowering, vernalization, and induction of bolting, are of great significance to commercial plant breeders, which makes manipulation of MADS genes a major avenue of research.