© 1994 Heron Publishing—Victoria, Canada
Accumulation of flavanols in yellowing beech leaves from forest decline sites
W. Feucht, D. Treutter and E. Christ
Technical University of Munich, Faculty of Agriculture and Horticulture, D-8050 Freising-Weihenstephan, Germany / Received June 7, 1993
Summary
Beech leaves were sampled during two consecutive years from three sites characterized by forest decline. Both monomeric and
oligomeric flavanols from green and yellowing leaves were determined quantitatively by reversed-phase, high-performance liquid
chromatography (HPLC) combined with a chemical reaction detection technique (CRD). Yellowing leaves generally contained more
than twice the quantity of flavanols than normal green leaves. The monomeric flavanols, epicatechin and (+)-catechin, comprised
up to 80% of the total flavanol fraction. Histochemical staining with p-dimethylaminocinnamaldehyde was used to determine local deposition of flavanols, including insoluble oligomeric flavanols,
in leaf tissues. The yellowing leaves stained intensely, whereas the green leaves stained lightly. Flavanol staining was strongest
in the spongy parenchyma followed by the palisade cells. The upper epidermis stained more intensely than the lower epidermis.
A 4-day treatment of small leaf pieces (5 × 5 mm) with 0.04 mM paraquat resulted in browning of the leaf pieces. The browning
reaction was prevented when the paraquat treatment was carried out in the presence of 0.16 mM (+)-catechin, indicating an
antioxidative property for this flavanol.
Keywords:
catechins, Fagus sylvatica, flavanols, forest decline, paraquat, proanthocyanidins.
