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Responses of epidermal phenolic compounds to light acclimation: In vivo qualitative and quantitative assessment using chlorophyll fluorescence excitation spectra in leaves of three woody species

Paper ID Volume ID Publish Year Pages File Format Full-Text
30984 44523 2007 17 PDF Available
Title
Responses of epidermal phenolic compounds to light acclimation: In vivo qualitative and quantitative assessment using chlorophyll fluorescence excitation spectra in leaves of three woody species
Abstract

Chlorophyll fluorescence (ChlF) excitation spectra were measured to assess the UV-sunscreen compounds accumulated in fully expanded leaves of three woody species belonging to different chemotaxons, (i.e. Morus nigra L., Prunus mahaleb L. and Lagerstroemia indica L.), grown in different light microclimates. The logarithm of the ratio of ChlF excitation spectra (logFER) between two leaves acclimated to different light microclimates was used to assess the difference in epidermal absorbance (EAbs). EAbs increased with increasing solar irradiance intercepted for the three species. This epidermal localisation of UV-absorbers was confirmed by the removal of the epidermis. It was possible to simulate EAbs as a linear combination of major phenolic compounds (Phen) identified in leaf methanol extracts by HPLC-DAD. Under UV-free radiation conditions, shaded leaves of M. nigra accumulated chlorogenic acid. Hydroxybenzoic acid (HBA) derivatives and hydroxycinnamic acid (HCA) derivatives greatly increased with increasing PAR irradiance under the low UV-B conditions found in the greenhouse. These traits were also observed for the HCA of the two other species. Flavonoid (FLAV) accumulation started under low UV-A irradiance, and became maximal in the adaxial epidermis of sun-exposed leaves outdoors. A decrease in the amount of HCA was observed concomitantly to the intense accumulation of FLAV for both leaf sides of the three species. Judging from the logFER, under low UV-B conditions, larger amounts of HCA are present in the epidermis in comparison to FLAV for the three species. Upon transition from the greenhouse to full sunlight outdoors, there was a decrease in leaf-soluble HCA that paralleled FLAV accumulation in reaction to increasing solar UV-B radiation in the three species. In M. nigra, that contains large amounts of HCA, the logFER analysis showed that this decrease occurred in the adaxial epidermis, whereas the abaxial epidermis, which is protected from direct UV-B radiation, continued to accumulate large amounts of HCA.

Keywords
Biospectroscopy; Chlorophyll fluorescence excitation spectra; Leaf polyphenols; Shading effect; Light acclimation; UV-absorbers
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Responses of epidermal phenolic compounds to light acclimation: In vivo qualitative and quantitative assessment using chlorophyll fluorescence excitation spectra in leaves of three woody species
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 88, Issues 2–3, 25 September 2007, Pages 163–179
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us