Molecular evolution and functional specialization of chalcone synthase superfamily from Phalaenopsis Orchid
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, EC22.214.171.124), 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.
KeywordsChalcone synthase Expression regulation Gene duplication Phalaenopsis Phylogenetic
polymerase chain reaction
Unable to display preview. Download preview PDF.
- Feinbaum RL, Ausubel FM (1988) Transcriptional regulation of the Arabidopsis thaliana chalcone sythase gene. Mol Cell Biol 8:985–1992Google Scholar
- Han YY, Ming F, Wang JW, Ye MM, Shen DL (2005) Molecular characterization and functional analysis of a novel chalcone synthase gene from Phalaenopsis Orchid in transgenic tobacco. Plant Mol Biol Rep 23:193–193Google Scholar
- Helariutta Y, Kotilainen M, Elomaa P, Kalkkinen N, Bremer K, Teeri TH, Albert VA (1996) Duplication and functional divergence in the chalcone synthase gene family of Asteraceae: evolution with substrate change and catalytic simplification. Proc Natl Acad Sci USA 93:9033–9038PubMedCrossRefGoogle Scholar
- Helariutta Y, Elomma P, Kotilainen M, Griesbach RJ, Schroder J, Teeri TH (1995) Chalcone synthase-like genes active during corolla development are differentially expressed and encode enzyme with different catalytic properties in Gerbera hybrida (Asteraceae). Plant Mol Biol 28:47–60PubMedCrossRefGoogle Scholar
- Kumar S, Tamura K, Jakobsen IB, Nei M (2001) MEGA2: molecular evolutionary genetics analysis software. Arizona State University, Tempe, ArizGoogle Scholar
- Li WH (1997) Molecular evolution. Sinauer Associate, Inc., Sunderland, MassGoogle Scholar
- Muse SV, Gaut BS (1994) A likelihood approach for comparing synonymous and nonsynonymous nucleotide substitution rates with application to the chloroplast genome. Mol Biol Evol 3:418–426Google Scholar
- Shiokawa K, Inagaki Y, Mor H, Hsu T, Iida S, Noguchi H (2000) The functional expression of the CHS-D and CHS-E genes of the common morning glory(Ipomoea purpurea) in Escherichia coli and characterization of their gene products. Plant Biotechnol 17:203–210Google Scholar
- Taylor LP, Jorgensen R (1992) Conditional male fertility in chalcone synthase-deficient petunia. J Heredity 831:1–17Google Scholar