The Evolution of the SEPALLATA Subfamily of MADS-Box GenesSequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. AY850178, AY850179, AY850180, AY850181, AY850182, AY850183, AY850184, AY850185, AY850186.

Abstract

Members of the SEPALLATA (SEP ) MADS-box subfamily are required for specifying the "floral state" by contributing to floral organ and meristem identity. SEP genes have not been detected in gymnosperms and seem to have originated since the lineage leading to extant angiosperms diverged from extant gymnosperms. Therefore, both functional and evolutionary studies suggest that SEP genes may have been critical for the origin of the flower. To gain insights into the evolution of SEP genes, we isolated nine genes from plants that occupy phylogenetically important positions. Phylogenetic analyses of SEP sequences show that several gene duplications occurred during the evolution of this subfamily, providing potential opportunities for functional divergence. The first duplication occurred prior to the origin of the extant angiosperms, resulting in the AGL2/3/4 and AGL9 clades. Subsequent duplications occurred within these clades in the eudicots and monocots. The timing of the first SEP duplication approximately coincides with duplications in the DEFICIENS/GLOBOSA and AGAMOUS MADS-box subfamilies, which may have resulted from either a proposed genome-wide duplication in the ancestor of extant angiosperms or multiple independent duplication events. Regardless of the mechanism of gene duplication, these pairs of duplicate transcription factors provided new possibilities of genetic interactions that may have been important in the origin of the flower.

Inflorescence Meristem Identity in Rice Is Specified by Overlapping Functions of Three AP1/FUL-Like MADS Box Genes and PAP2, a SEPALLATA MADS Box Gene

“…The SEP subfamily of rice consists of five genes, including PAP2 (Malcomber and Kellogg, 2005;Zahn et al, 2005). As previously reported (Arora et al, 2007;Kobayashi et al, 2010), none of the other four SEP genes, MADS1, MADS5, MADS7, (A) Micrographs of the meristem stages that were analyzed.…”

Evolution ofAGL6-likeMADS Box Genes in Grasses (Poaceae): Ovule Expression Is Ancient and Palea Expression Is New

“…Phylogenetic analysis of MADS box genes and/or proteins has shown that AGL6-like genes are sister to the SEPALLATA-like genes (E-function) (Purugganan et al, 1995;Theissen et al, 2000;Zahn et al, 2005). AGL6-like genes have been found in both in angiosperms and gymnosperms but not in ferns (Theissen et al, 2000).…”

“…AGL6-like genes have been found in both in angiosperms and gymnosperms but not in ferns (Theissen et al, 2000). All members of the AGL6 and SEPALLATA clades share a conserved hydrophobic motif in the C-terminal domain, suggesting that they might potentially interact (Moon et al, 1999;Litt and Irish, 2003;Vandenbussche et al, 2003;Zahn et al, 2005).…”

Degradation of class E MADS-domain transcription factors in Arabidopsis by a phytoplasmal effector, phyllogen

“…16 It is also interesting from the perspective of the phylogenetic differences between SEP Keywords: Arabidopsis, floral development, MADS transcription factors, phyllody, phyllogen, phytoplasma, SEPALLATA genes: in an evolutionary analysis of SEP gene sub-family, SEP3 and the other 3 SEP genes of Arabidopsis were divided into 2 different clades. 17 In this study, we examined whether a phyllogen degrades SEP1, SEP2, and SEP4 of Arabidopsis. We transiently expressed YFP-fused SEP1, SEP2, SEP3, SEP4, or bZIP63, a basic leucine zipper transcription factor involved in the glucose-abscisic acid interaction network of Arabidopsis, 18 in Nicotiana benthamiana leaves by agroinfiltration in combination with either GUS protein (control) or a phyllogen (PHYL1) of OY-W phytoplasma, 19 and monitored their accumulation and subcellular localization by confocal microscopy.…”

“…1,4,14,15 Moreover, SEP3-and SEP1/2/4-like genes are highly conserved among various angiosperms as genes of the SEP sub-family encoding class E MADS TFs. 17 Therefore, it is likely that phyllogens broadly target class E proteins of angiosperms, including eudicots, monocots, and other taxa, for degradation. Future studies investigating the target specificity of phyllogens will shed further light on the relationships between phyllody caused by phytoplasmas and the function of class E genes in angiosperms.…”