Issue 7, 2019

Hydroxycinnamic acids in sunflower leaves serve as UV-A screening pigments

Abstract

Flavonoids and hydroxycinnamic acid derivatives, which are located in the upper epidermis of plants, are well known to screen ultraviolet radiation, thus protecting the underlying tissue from these harmful wavelengths. Both classes of secondary products complement each other over the UV spectral region according to their absorption spectra: flavonoids are most efficient as UV-A attenuators while hydroxycinnamates (HCAs) screen well within the UV-B region. Analysis of epidermal transmittance revealed a substantial UV-A screen in Helianthus annuus L. cv. Peredovick. Identifying responsible pigments by HPLC-MS, we found surprisingly low amounts of flavonoids but dominant abundance of the HCA derivatives chlorogenic and di-caffeoyl quinic acid. Both display low UV-A absorbance and thus, should contribute only a little to UV-A protection. However, growth at high light led to a decrease of epidermal transmittance at 366 nm of up to 90%. Underpinning the screening role, HCA autofluorescence microscopy revealed storage to occur predominantly in vacuoles of the upper epidermis. UV-A treatment in the absence of D1-repair resulted in photosystem II inactivation proportional to epidermal UV-A transmittance. Our findings suggest that UV-A protection can be achieved solely with HCAs, apparently through accumulation of high amounts of these compounds.

Graphical abstract: Hydroxycinnamic acids in sunflower leaves serve as UV-A screening pigments

Supplementary files

Article information

Article type
Paper
Submitted
01 oct. 2018
Accepted
01 mai 2019
First published
09 mai 2019

Photochem. Photobiol. Sci., 2019,18, 1649-1659

Hydroxycinnamic acids in sunflower leaves serve as UV-A screening pigments

J. Stelzner, R. Roemhild, A. Garibay-Hernández, B. Harbaum-Piayda, H. Mock and W. Bilger, Photochem. Photobiol. Sci., 2019, 18, 1649 DOI: 10.1039/C8PP00440D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements