Dynamics of flavonol accumulation in leaf tissues under different UV-B regimes in Centella asiatica (Apiaceae)

• Published in: Planta 2015-09, Vol.242 (3), p.545-559
• Main Authors: Bidel, Luc P. R., Chomicki, Guillaume, Bonini, Fabien, Mondolot, Laurence, Soulé, Julien, Coumans, Marc, La Fisca, Philippe, Baissac, Yves, Petit, Virginie, Loiseau, Alain, Cerovic, Zoran G., Gould, Kevin S., Jay-Allemand, Christian
• Format: Article
• Language: English
• Subjects: Accumulation; Agricultural sciences; Agriculture; Apiaceae - metabolism; Apiaceae - radiation effects; Biomedical and Life Sciences; Biosynthesis; Ecology; Epidermis; Flavonols - metabolism; Forestry; Leaves; Life Sciences; Liquid chromatography; Mass spectrometry; Original Article; Plant Leaves - metabolism; Plant Leaves - radiation effects; Plant Sciences; Plant tissues; Polyphenols: biosynthesis and function in plants and ecosystems; Ultraviolet Rays; Vegetal Biology
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-015-2291-7

Main conclusion 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.