title: Histochemical screening, metabolite profiling and expression analysis reveal Rosaceae roots as the site of flavan-3-ol biosynthesis.
abstract: Histochemical screening of 30 Rosaceae genera representing all classic subfamilies demonstrated flavan-3-ols (catechins) as general secondary metabolites in roots of Rosaceae. Semi-quantitative LC-MS analyses confirmed the presence of catechin, epicatechin and various dimeric flavan-3-ols (also representing higher polymeric proanthocyanidins) as prominent polyphenols in root tips of Fragaria (strawberry), Malus (apple), Rosa (rose), Pyrus (pear) and Prunus (plum). Distinct patterns of flavan-3-ol distribution at the cellular level were found in strawberry (Fragaria × ananassa) and apple (Malus × domestica) root tips. The calyptras (root caps) showed the most prominent flavan-3-ol staining for these two genera. Border cells of Fragaria and Malus, as first demonstrated here for Rosaceae, were also found to contain flavan-3-ols. Transcript analyses with cDNA demonstrated root expression of known flavonoid genes expressed in the respective fruits and leaves. Primarily, this proves in situ biosynthesis of flavan-3-ols in these roots. Knowledge of the distinct cellular distribution patterns and their in situ biosynthesis in roots provides a basis for analysis of the functional roles of Rosaceae root flavan-3-ols.
authors.affiliation: Biotechnology of Natural Products, Technical University Munich, Freising, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Hoffmann
authors.forename: R
authors.initials: R
authors.lastname: Friedlhuber
authors.forename: C
authors.initials: C
authors.lastname: Steinhauser
authors.forename: I
authors.initials: I
authors.lastname: Tittel
authors.forename: K
authors.initials: K
authors.lastname: Skowranek
authors.forename: W
authors.initials: W
authors.lastname: Schwab
authors.forename: T C
authors.initials: TC
authors.lastname: Fischer
mesh_terms: D001692:Biological Transport; D002392:Catechin / Q000096:biosynthesis; D005419:Flavonoids / Q000096:biosynthesis*; D005638:Fruit / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006651:Histocytochemistry; D010937:Plant Growth Regulators / Q000096:biosynthesis; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism*; D044945:Proanthocyanidins / Q000096:biosynthesis; D027824:Rosaceae / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D005419:Flavonoids; D010937:Plant Growth Regulators; D044945:Proanthocyanidins; C404987:flavan-3-ol; D002392:Catechin