title: Dynamics of flavonol accumulation in leaf tissues under different UV-B regimes in Centella asiatica (Apiaceae).
abstract: A cumulative effect of UV-B doses on epidermal flavonol accumulation was observed during the first week of a time course study in Centella asiatica (Apiaceae). However, once flavonol levels had peaked, additional accumulation was possible only if higher daily UV-B irradiances were applied. We aimed to understand the dynamics of flavonol accumulation in leaf tissues using non-destructive spectroscopy and HPLC-mass spectrometry. When leaves that had grown without UV-B were given brief daily exposures to low-irradiance UV-B, they accumulated flavonols, predominantly kaempferol-3-O-β-D-glucuronopyranoside and quercetin-3-O-β-D-glucuronopyranoside, in their exposed epidermis, reaching a plateau after 7 days. More prolonged UV-B exposures or higher doses eventually augmented flavonol concentrations even in non-exposed tissues. If UV-B irradiance was subsequently reduced, leaves appeared to lose their ability to accumulate further flavonols in their epidermis even if the duration of daily exposure was increased. A higher irradiance level was then necessary to further increase flavonol accumulation. When subsequently acclimated to higher UV-B irradiances, mature leaves accumulated less flavonols than did developing ones. Our study suggests that levels of epidermal flavonols in leaves are governed primarily by UV-B irradiance rather than by duration of exposure.
authors.affiliation: INRA, UMR AGAP, Centre de Recherche de Montpellier, 2 Place Pierre Viala-Bât. 21, 34060, Montpellier, France, Luc.Bidel@univ-montp2.fr.
authors.forename: Luc P R
authors.initials: LP
authors.lastname: Bidel
authors.forename: Guillaume
authors.initials: G
authors.lastname: Chomicki
authors.forename: Fabien
authors.initials: F
authors.lastname: Bonini
authors.forename: Laurence
authors.initials: L
authors.lastname: Mondolot
authors.forename: Julien
authors.initials: J
authors.lastname: Soulé
authors.forename: Marc
authors.initials: M
authors.lastname: Coumans
authors.forename: Philippe
authors.initials: P
authors.lastname: La Fisca
authors.forename: Yves
authors.initials: Y
authors.lastname: Baissac
authors.forename: Virginie
authors.initials: V
authors.lastname: Petit
authors.forename: Alain
authors.initials: A
authors.lastname: Loiseau
authors.forename: Zoran G
authors.initials: ZG
authors.lastname: Cerovic
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Gould
authors.forename: Christian
authors.initials: C
authors.lastname: Jay-Allemand
mesh_terms: D019661:Apiaceae / Q000378:metabolism* / Q000528:radiation effects; D044948:Flavonols / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D044948:Flavonols