title: Ultraviolet irradiation induces accumulation of isoflavonoids and transcription of genes of enzymes involved in the calycosin-7-O-β-d-glucoside pathway in Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao.
abstract: Isoflavonoids are a group of phenolic secondary metabolites found almost exclusively in leguminous plants. Formononetin, calycosin and calycosin-7-O-β-d-glucoside (CG) are isoflavonoid products in the CG pathway. Accumulation of the three isoflavonoids plus daidzein and expression of six genes of enzymes involved in the CG pathway were studied in Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao with ultraviolet (UV) irradiation. Our results showed that (1) main isoflavonoids in roots, stems and leaves were CG, daidzein and calycosin, respectively; they accumulated significantly under the induction of UV irradiation during 8 days but their content declined later; (2) expression of six genes of enzymes involved in the CG pathway was inhibited slightly at early stage but the expression was increased greatly afterward; (3) chalcone synthase, chalcone reductase and chalcone isomerase were expressed to their individual maximum level within shorter hours than were cinnamate 4-hydroxylase, isoflavone synthase (IFS) and isoflavone 3'-hydroxylase and (4) more calycosin but less daidzein accumulated in leaves. IFS was highly expressed in leaves, which might lead to high accumulation of the common precursor of daidzein and 2,7-dihydroxy-4'-O-methoxy-isoflavanone, the latter of which would be converted to formononetin, calycosin and CG via a series of reactions. Little daidzein accumulated in leaves, which suggested that rather than be converted to daidzein, the 2,7,4'-trihydroxyisoflavanone was probably more easily caught by 2-hydroxyisoflavanone 4'-O-methyltransferase and hence provided more precursors for formononetin. The findings were discussed in terms of the influence of UV irradiation in the accumulation of isoflavonoids.
authors: Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Fudan University, Shanghai, China.
authors: Rong-Yan
authors: RY
authors: Xu
authors: Peng
authors: P
authors: Nan
authors: Yixin
authors: Y
authors: Yang
authors: Haiyun
authors: H
authors: Pan
authors: Tongshui
authors: T
authors: Zhou
authors: Jiakuan
authors: J
authors: Chen
mesh_terms: D027885:Astragalus propinquus / Q000201:enzymology* / Q000235:genetics* / Q000528:radiation effects; D053898:Biosynthetic Pathways / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D017343:Genes, Plant / Q000235:genetics; D005960:Glucosides / Q000378:metabolism*; D007529:Isoflavones / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000235:genetics / Q000528:radiation effects; D018515:Plant Leaves / Q000235:genetics / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D005960:Glucosides; D007529:Isoflavones; D010940:Plant Proteins; C526426:calycosin-7-O-beta-D-glucoside