Epidermal UVA screening capacity measured in situ as an indicator of light acclimation state of leaves of a very plastic alpine plant Soldanella alpina L

• Published in: Plant physiology and biochemistry Vol. 151; no. 10; pp. 10 - 20
• Main Authors: Bidel, Luc P.R., Meyer, Sylvie, Talhouët, Anne-Claire, Baudin, Xavier, Daniel, Caroline, Cazals, Guillaume, Streb, Peter
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.06.2020; Elsevier
• Subjects: Acclimatization; Carotenoids; Chlorophyll; Dualex; Epidermal UV absorbance; Flavonoids; Leaf flavonoids; Life Sciences; Light acclimation; Photosynthesis; Plant Leaves; Primulaceae; Soldanella alpina; Sunlight Ultraviolet Rays; Vegetal Biology; Soldanella alpina; LMA; UV; Leaf flavonoids; Chl-index; Chl; Dualex; Epidermal UV absorbance; HCA; Light acclimation; DEA322, DEA375; Car; m/z; Flav
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2020.02.045

Soldanella alpina differing in leaf epidermal UV-A absorbance (DEA375), as measured with the Dualex, was investigated as a model alpine plant for the flavonoid (Flav) composition and concentration and for anatomical and pigment characteristics. In sun leaves, twenty-three flavones were characterised by their mass formula, their maximum absorption, their glycosylation, their methylation and dehydroxylation pattern. The flavones belonged to four subfamilies (tetra-hydroxy-flavones, penta-hydroxy-flavones, penta-hydroxy-methyl-flavones and tri-hydroxy-di-methoxy-flavones), abundant in sun and shade leaves. Their concentration was estimated by their absorption at 350 nm after HPLC separation. Sun leaves contained relatively higher contents of penta-hydroxy-methyl-flavones and shade leaves higher contents of tetra-hydroxy-flavones. The flavones were present mainly in vacuoles, all over the leaf. After shade-sun transfer, the content of most flavones increased, irrespective of the presence or absence of UV radiation. Highly significant correlations with the log-transformed DEA375 suggest that DEA375 can be readily applied to predict the flavone content of S. alpina leaves. Shade-sun transfer of leaves decreased the hydroxycinnamic acid (HCA) content, the mass-based chlorophyll (Chl) a+b content and the Chl/Carotenoid (Car) ratio but increased DEA375, and the Car content. Together with previously reported anatomical characteristics all these parameters correlated significantly with the DEA375. The Flav content is therefore correlated to most of the structural characteristics of leaf acclimation to light and this can be probed in situ by DEA375. •S. alpina leaves have twenty-three different flavones belonging to four subfamilies.•The flavones show different methylation and glycosylation pattern.•The flavonoids increased in response to sunlight independent of UV-radiation and were distributed over the whole leaf.•Optical measurements in situ, correlate to the flavonoid pattern, the leaf anatomy and the carotenoid content.