title: Differential stress-response expression of two flavonol synthase genes and accumulation of flavonols in tartary buckwheat.
abstract: Flavonoids are ubiquitously present in plants and play important roles in these organisms as well as in the human diet. Flavonol synthase (FLS) is a key enzyme of the flavonoid biosynthetic pathway, acting at the diverging point into the flavonol subclass branch. We isolated and characterized a FLS isoform gene, FtFLS2, from tartary buckwheat (Fagopyrum tataricum). FtFLS2 shares 48% identity and 67% similarity with the previously reported FtFLS1, whereas both genes share 47-65% identity and 65-69% similarity with FLSs from other plant species. Using quantitative real-time PCR and high-performance liquid chromatography (HPLC), the expression of FtFLS1/2 and the production of 3 main flavonols (kaempferol, myricetin and quercetin) was detected in roots, leaves, stems, flowers and different stages of developing seeds. The relationship between the expression of the 2 FLS genes and the accumulation of the 3 basic flavonols was analyzed in 2 tartary buckwheat cultivars. FtFLS1 and FtFLS2 exhibited differential transcriptional levels between the tartary buckwheat cultivars 'Hokkai T10' and 'Hokkai T8'. Generally, higher transcript levels of FtFLS1 and FtFLS2 and a higher amount of flavonols were observed in the 'Hokkai T10' cultivar than 'Hokkai T8'. The content of flavonols showed tissue-specific accumulation between the 2 cultivars. The transcription of FtFLS1 was inhibited by the exogenous application of abscisic acid (ABA), salicylic acid (SA) and sodium chloride (NaCl), while FtFLS2 was not affected by ABA but up-regulated by SA and NaCl. These data indicate that the 2 FtFLS isoforms of buckwheat have different functions in the response of buckwheat to environmental stress.
authors.affiliation: Department of Crop Science, Chungnam National University, 99 Daehak-Ro, Yuseong-gu, Daejeon 305-764, Republic of Korea.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Li
authors.forename: Yeon Bok
authors.initials: YB
authors.lastname: Kim
authors.forename: Yeji
authors.initials: Y
authors.lastname: Kim
authors.forename: Shicheng
authors.initials: S
authors.lastname: Zhao
authors.forename: Haeng Hoon
authors.initials: HH
authors.lastname: Kim
authors.forename: Eunsook
authors.initials: E
authors.lastname: Chung
authors.forename: Jai-Heon
authors.initials: JH
authors.lastname: Lee
authors.forename: Sang Un
authors.initials: SU
authors.lastname: Park
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D019612:Fagopyrum / Q000201:enzymology* / Q000235:genetics*; D005419:Flavonoids / Q000378:metabolism; D044948:Flavonols / Q000737:chemistry / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D006801:Humans; D044949:Kaempferols / Q000378:metabolism; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011794:Quercetin / Q000378:metabolism; D036226:Seedlings / Q000235:genetics; D016415:Sequence Alignment; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D005419:Flavonoids; D044948:Flavonols; D044949:Kaempferols; D010940:Plant Proteins; C006552:kaempferol; C040015:myricetin; D011794:Quercetin; D010088:Oxidoreductases; C085313:flavonol synthase
keywords: ABA; Environmental stress; FLS; Flavonol biosynthesis; Flavonol synthase; Gene expression; HPLC; NaCl; SA; Tartary buckwheat; abscisic acid; flavonol synthase; high-performance liquid chromatography; salicylic acid; sodium chloride