title: Diurnal and light regulation of sulphur assimilation and glucosinolate biosynthesis in Arabidopsis.
abstract: Glucosinolates are a major class of sulphur-containing secondary metabolites involved in plant defence against pathogens. Recently many regulatory links between glucosinolate biosynthesis and sulphate assimilation were established. Since sulphate assimilation undergoes diurnal rhythm and is light regulated, this study analysed whether the same is true for glucosinolate biosynthesis. The levels of glucosinolates and glutathione were found to be higher during the day than during the night. This agreed with variation in sulphate uptake as well as activity of the key enzyme of the sulphate assimilation pathway, adenosine 5'-phosphosulphate reductase. Correspondingly, the flux through sulphate assimilation was higher during the day than during the night, with the maximum flux through primary assimilation preceding maximal incorporation into glucosinolates. Prolonged darkness resulted in a strong reduction in glucosinolate content. Re-illumination of such dark-adapted plants induced accumulation of mRNA for many genes of glucosinolate biosynthesis, leading to increased glucosinolate biosynthesis. The light regulation of the glucosinolate synthesis genes as well as many genes of primary sulphate assimilation was controlled at least partly by the LONG HYPOCOTYL5 (HY5) transcription regulator. Thus, glucosinolate biosynthesis is highly co-regulated with sulphate assimilation.
authors: Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich, UK. stine_huseby@yahoo.no
authors: Stine
authors: S
authors: Huseby
authors: Anna
authors: A
authors: Koprivova
authors: Bok-Rye
authors: BR
authors: Lee
authors: Shikha
authors: S
authors: Saha
authors: Richard
authors: R
authors: Mithen
authors: Anne-Berit
authors: AB
authors: Wold
authors: Gunnar B
authors: GB
authors: Bengtsson
authors: Stanislav
authors: S
authors: Kopriva
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005961:Glucosinolates / Q000096:biosynthesis*; D005978:Glutathione / Q000235:genetics / Q000378:metabolism; D008027:Light; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013462:Sulfur Radioisotopes / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D005961:Glucosinolates; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D012333:RNA, Messenger; D013431:Sulfates; D013462:Sulfur Radioisotopes; D013455:Sulfur; D005978:Glutathione