The interplay of anthocyanin biosynthesis and chlorophyll catabolism in senescing leaves and the question of photosystem II photoprotection
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Fully exposed, senescing leaves of Cornus sanguinea and Parthenocissus quinquefolia display during autumn considerable variation in both anthocyanin and chlorophyll (Chl) concentrations. They were used in this study to test the hypothesis that anthocyanins may have a photoprotective function against photosystem II (PSII) photoinhibitory damage. The hypothesis could not be confirmed with field sampled leaves since maximum photochemical efficiency (Fv/Fm) of PSII was negatively correlated to anthocyanin concentration and the possible effects of anthocyanins were also confounded by a decrease in Fv/Fm with Chl loss. However, after short-term laboratory photoinhibitory trials, the percent decrease of Fv/Fm was independent of Chl concentration. In this case, a slight alleviation of PSII damage with increasing anthocyanins was observed in P. quinquefolia, while a similar trend in C. sanguinea was not statistically significant. It is inferred that the assumed photoprotection, if addressed to PSII, may be of limited advantage and only under adverse environmental conditions.
Additional keywordsanthocyanins chlorophyll fluorescence Cornus sanguinea Parthenocissus quinquefolia photoinhibition photoprotection senescence
anthocyanin reflectance index
minimal fluorescence yield of dark-adapted state
maximum fluorescence yield of dark-adapted state
maximum photochemical efficiency of PSII
Karlsruhe Institute of Technology
near infrared reflectance
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