title: Molecular evolution and functional specialization of chalcone synthase superfamily from Phalaenopsis orchid.
abstract: Plant genomes appear to exploit the process of gene duplication as a primary means of acquiring biochemical and developmental flexibility. The best example is the gene encoding chalcone synthase (CHS, EC2.3.1.74), the first committed step in flavonoid biosynthesis. In this study, we examined the molecular evolution of three CHS family members of Phalaenopsis including a novel chs gene (phchs5), which is slowly evolved. The inferred phylogeny of the chs genes of Phalaenopsis with other two orchid plants, Bromoheadia finlaysoniana and Dendrobium hybrid, suggested that gene duplication and divergence have occurred before divergence of these three genera. Relatively quantitative RT-PCR analysis identified expression patterns of these three chs genes in different floral tissues at different developmental stages. Phchs5 was the most abundantly expressed chs gene in floral organs and it was specifically transcribed in petal and lip at the stages when anthocyanin accumulated (stage1-4). Phchs3 and phchs4 were expressed at much lower levels than phchs5. Phchs3 was expressed in pigmented tissue (including lip, petal and sepal) at middle stages (stages 2-4) and in colorless reproductive tissue at late stage (stage 5). Phchs4 was only expressed in petal at earlier stages (stage 1-3) and in lip at middle stage (stage 4). These results present new data on differentiation of gene expression among duplicate copies of chs genes in Phalaenopsis.
authors.affiliation: State Key Laboratory of Genetic Engineering, Research Centre of Gene Diversity and Designed Agriculture, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science, Fudan University, Shanghai, China,
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Han
authors.forename: Feng
authors.initials: F
authors.lastname: Ming
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Jing-Wen
authors.initials: JW
authors.lastname: Wang
authors.forename: Ming-Ming
authors.initials: MM
authors.lastname: Ye
authors.forename: Da-Leng
authors.initials: DL
authors.lastname: Shen
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D031667:Dendrobium / Q000201:enzymology / Q000235:genetics; D019143:Evolution, Molecular; D020440:Gene Duplication; D017343:Genes, Plant; D008969:Molecular Sequence Data; D005810:Multigene Family; D029595:Orchidaceae / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics*; D010641:Phenotype; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D018744:DNA, Plant; D000217:Acyltransferases; C020141:flavanone synthetase