title: Chalcone synthase family genes have redundant roles in anthocyanin biosynthesis and in response to blue/UV-A light in turnip (Brassica rapa; Brassicaceae).
abstract: OBJECTIVE
  The epidermis of Brassica rapa (turnip) cv. Tsuda contains light-induced anthocyanins, visible signs of activity of chalcone synthase (CHS), a key anthocyanin biosynthetic enzyme, which is encoded by the CHS gene family. To elucidate the regulation of this light-induced pigmentation, we isolated Brassica rapa CHS1-CHS6 (BrCHS1-CHS6) and characterized their cis-elements and expression patterns.
  
  
  METHODS
  Epidermises of light-exposed swollen hypocotyls (ESHS) were harvested to analyze transcription levels of BrCHS genes by real-time PCR. Different promoters for the genes were inserted into tobacco to examine pCHS-GUS activity by histochemistry. Yeast-one-hybridization was used to detect binding activity of BrCHS motifs to transcription factors.
  
  
  RESULTS
  Transcript levels of BrCHS1, -4, and -5 and anthocyanin-biosynthesis-related genes F3H, DFR, and ANS were high, while those of BrCHS2, -3, and -6 were almost undetectable in pigmented ESHS. However, in leaves, CHS5, F3H, and ANS expression was higher than in nonpigmented ESHS, but transcription of DFR was not detected. In the analysis of BrCHS1 and BrCHS3 promoter activity, GUS activity was strong in pigmented flowers of BrPCHS1-GUS-transformed tobacco plants, but nearly absent in BrPCHS3-GUS-transformed plants. Transcript levels of regulators, BrMYB75 and BrTT8, were strongly associated with the anthocyanin content and were light-induced. Coregulated cis-elements were found in promoters of BrCHS1,-4, and -5, and BrMYB75 and BrTT8 had high binding activities to the BrCHS Unit 1 motif.
  
  
  CONCLUSIONS
  The chalcone synthase gene family encodes a redundant set of light-responsive, tissue-specific genes that are expressed at different levels and are involved in flavonoid biosynthesis in Tsuda turnip.
authors.affiliation: College of Life Science, Northeast Forestry University, 26 Hexing Road, Harbin 150040, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Yaguang
authors.initials: Y
authors.lastname: Zhan
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Li
authors.forename: Saneyuki
authors.initials: S
authors.lastname: Kawabata
mesh_terms: D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D000872:Anthocyanins / Q000096:biosynthesis / Q000235:genetics*; D029741:Brassica rapa / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D035264:Flowers / Q000201:enzymology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D010860:Pigments, Biological / Q000096:biosynthesis / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D010860:Pigments, Biological; D010940:Plant Proteins; D014157:Transcription Factors; D000217:Acyltransferases; C020141:flavanone synthetase
keywords: Brassica rapa; Brassicaceae; CHS; UV-A; anthocyanin; gene family