title: Analysis of the floral MADS-box genes from monocotyledonous Trilliaceae species indicates the involvement of SEPALLATA3-like genes in sepal-petal differentiation.
abstract: The evolution of greenish sepals from petaloid outer tepals has occurred repeatedly in various lineages of non-grass monocots. Studies in distinct monocot species showed that the evolution of sepals could be explained by the ABC model; for example, the defect of B-class function in the outermost whorl was linked to the evolution of sepals. Here, floral MADS-box genes from three sepal-bearing monocotyledonous Trilliaceae species, Trillium camschatcense, Paris verticillata, and Kinugasa japonica were examined. Unexpectedly, expression of not only A- but also B-class genes was detected in the sepals of all three species. Although the E-class gene is generally expressed across all floral whorls, no expression was detected in sepals in the three species examined here. Overexpression of the E-class SEPALLATA3-like gene from T. camschatcense (TcamSEP) in Arabidopsis thaliana produced phenotypes identical to those reported for orthologs in other monocots. Additionally, yeast hybrid experiments indicated that TcamSEP could form a higher-order complex with an endogenous heterodimer of B-class APETALA3/DEFICIENS-like (TcamDEF) and PISTILLATA/GLOBOSA-like (TcamGLO) proteins. These results suggest a conserved role for Trilliaceae SEPALLATA3-like genes in functionalization of the B-class genes, and that a lack of SEPALLATA3-like gene expression in the outermost whorl may be related to the formation of greenish sepals.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan. Electronic address: skubota44@gmail.com.
authors.forename: Shosei
authors.initials: S
authors.lastname: Kubota
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan. Electronic address: kanno@ige.tohoku.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Kanno
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D019143:Evolution, Molecular; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D019668:Liliaceae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D016415:Sequence Alignment; D031446:Trillium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D026161:MADS Domain Proteins; D010940:Plant Proteins
keywords: ABC model; E-class gene; Flower development; Kinugasa japonica; Paris verticillata; Trillium camschatcense