title: An ancestral MADS-box gene duplication occurred before the divergence of plants and animals.
abstract: Changes in genes encoding transcriptional regulators can alter development and are important components of the molecular mechanisms of morphological evolution. MADS-box genes encode transcriptional regulators of diverse and important biological functions. In plants, MADS-box genes regulate flower, fruit, leaf, and root development. Recent sequencing efforts in Arabidopsis have allowed a nearly complete sampling of the MADS-box gene family from a single plant, something that was lacking in previous phylogenetic studies. To test the long-suspected parallel between the evolution of the MADS-box gene family and the evolution of plant form, a polarized gene phylogeny is necessary. Here we suggest that a gene duplication ancestral to the divergence of plants and animals gave rise to two main lineages of MADS-box genes: TypeI and TypeII. We locate the root of the eukaryotic MADS-box gene family between these two lineages. A novel monophyletic group of plant MADS domains (AGL34 like) seems to be more closely related to previously identified animal SRF-like MADS domains to form TypeI lineage. Most other plant sequences form a clear monophyletic group with animal MEF2-like domains to form TypeII lineage. Only plant TypeII members have a K domain that is downstream of the MADS domain in most plant members previously identified. This suggests that the K domain evolved after the duplication that gave rise to the two lineages. Finally, a group of intermediate plant sequences could be the result of recombination events. These analyses may guide the search for MADS-box sequences in basal eukaryotes and the phylogenetic placement of new genes from other plant species.
authors.affiliation: Department of Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA. abuylla@servidor.unam.mx
authors.forename: E R
authors.initials: ER
authors.lastname: Alvarez-Buylla
authors.forename: S
authors.initials: S
authors.lastname: Pelaz
authors.forename: S J
authors.initials: SJ
authors.lastname: Liljegren
authors.forename: S E
authors.initials: SE
authors.lastname: Gold
authors.forename: C
authors.initials: C
authors.lastname: Burgeff
authors.forename: G S
authors.initials: GS
authors.lastname: Ditta
authors.forename: L
authors.initials: L
authors.lastname: Ribas de Pouplana
authors.forename: L
authors.initials: L
authors.lastname: Martínez-Castilla
authors.forename: M F
authors.initials: MF
authors.lastname: Yanofsky
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D019143:Evolution, Molecular; D005658:Fungi / Q000235:genetics; D020440:Gene Duplication; D014644:Genetic Variation; D026161:MADS Domain Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics; D010944:Plants / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D026161:MADS Domain Proteins; D010940:Plant Proteins; D014157:Transcription Factors