title: Identification and expression of isoflavone synthase, the key enzyme for biosynthesis of isoflavones in legumes.
abstract: Isoflavones have drawn much attention because of their benefits to human health. These compounds, which are produced almost exclusively in legumes, have natural roles in plant defense and root nodulation. Isoflavone synthase catalyzes the first committed step of isoflavone biosynthesis, a branch of the phenylpropanoid pathway. To identify the gene encoding this enzyme, we used a yeast expression assay to screen soybean ESTs encoding cytochrome P450 proteins. We identified two soybean genes encoding isoflavone synthase, and used them to isolate homologous genes from other leguminous species including red clover, white clover, hairy vetch, mung bean, alfalfa, lentil, snow pea, and lupine, as well as from the nonleguminous sugarbeet. We expressed soybean isoflavone synthase in Arabidopsis thaliana, which led to production of the isoflavone genistein in this nonlegume plant. Identification of the isoflavone synthase gene should allow manipulation of the phenylpropanoid pathway for agronomic and nutritional purposes.
authors.affiliation: Agricultural Biotechnology, The Dupont Company, Experimental Station; Wilmington, DE 19880-0402, USA.
authors.forename: W
authors.initials: W
authors.lastname: Jung
authors.forename: O
authors.initials: O
authors.lastname: Yu
authors.forename: S M
authors.initials: SM
authors.lastname: Lau
authors.forename: D P
authors.initials: DP
authors.lastname: O'Keefe
authors.forename: J
authors.initials: J
authors.lastname: Odell
authors.forename: G
authors.initials: G
authors.lastname: Fader
authors.forename: B
authors.initials: B
authors.lastname: McGonigle
mesh_terms: D000872:Anthocyanins / Q000096:biosynthesis; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D019663:Chenopodiaceae / Q000201:enzymology / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D007887:Fabaceae / Q000201:enzymology / Q000235:genetics*; D044950:Flavanones; D005419:Flavonoids / Q000378:metabolism; D017343:Genes, Plant; D005822:Genetic Vectors; D019833:Genistein / Q000378:metabolism; D015698:Genomic Library; D007529:Isoflavones / Q000378:metabolism*; D008031:Lignin / Q000096:biosynthesis; D010105:Oxygenases / Q000096:biosynthesis / Q000235:genetics*; D030821:Plants, Genetically Modified; D010946:Plants, Medicinal; D017422:Sequence Analysis, DNA; D013025:Glycine max / Q000201:enzymology / Q000235:genetics
chemical_list: D000872:Anthocyanins; D044950:Flavanones; D005419:Flavonoids; D007529:Isoflavones; C004742:daidzein; D008031:Lignin; D003577:Cytochrome P-450 Enzyme System; D019833:Genistein; D010105:Oxygenases; C048489:isoflavone synthase; C005273:naringenin