title: Sequence evolution and sex-specific expression patterns of the C class floral identity gene, SpAGAMOUS, in dioecious Spinacia oleracea L.
abstract: Development in dioecious cultivated spinach, Spinacia oleracea, is distinguished by the absence of alternative reproductive organ primordia in male and female flowers. Given the highly derived floral developmental program in spinach, we wished to characterize a spinach C class floral identity gene and to determine the patterns of sequence evolution as well as compare the spatial and temporal expression patterns with those of AGAMOUS. The isolated cDNA sequence clusters phylogenetically within the AGAMOUS/FARINELLI C class clade. In comparison with the SLM1 sequence from the related Silene latifolia, amino acid replacements are highly conservative and non-randomly distributed, being predominantly found in hinge regions or on exposed surfaces of helices. The spinach gene (SpAGAMOUS) appears to be exclusively expressed in reproductive tissues and not in vegetative organs. Initial expression of SpAGAMOUS is similar in male and female floral primordia. However, upon initiation of the first whorl organs, SpAGAMOUS becomes restricted to meristemic regions from which the reproductive primordia will develop. This results in an early gender-specific pattern. Thus, the spinach C class gene is differentially expressed prior to reproductive organ development and is, at least, correlated with, if not directly involved in, the sexual dimorphism in spinach.
authors.affiliation: Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
authors.forename: D Noah
authors.initials: DN
authors.lastname: Sather
authors.forename: Amber
authors.initials: A
authors.lastname: York
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Pobursky
authors.forename: Edward M
authors.initials: EM
authors.lastname: Golenberg
mesh_terms: D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D035264:Flowers / Q000235:genetics*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D026161:MADS Domain Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012727:Sex Characteristics; D018724:Spinacia oleracea / Q000235:genetics*
chemical_list: D026161:MADS Domain Proteins; D010940:Plant Proteins