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Effects of high light and desiccation on the operation of the xanthophyll cycle in two marine brown algae

Published online by Cambridge University Press:  01 February 1999

MARK HARKER
Affiliation:
School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK
CLAIRE BERKALOFF
Affiliation:
Dynamique et Photoregulation des Membranes Végétales, URA CNRS 1810, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris Cedex 05, France
YVES LEMOINE
Affiliation:
Cytophysiologie Végétale et Phycologie, Université de Lille, 59655 Villeneuve d'Ascq, France
GEORGE BRITTON
Affiliation:
Department of Biochemistry, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK
ANDREW J. YOUNG
Affiliation:
School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK
JEAN-CLAUDE DUVAL
Affiliation:
Dynamique et Photoregulation des Membranes Végétales, URA CNRS 1810, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris Cedex 05, France
NOUR-EDDINE RMIKI
Affiliation:
Cytophysiologie Végétale et Phycologie, Université de Lille, 59655 Villeneuve d'Ascq, France
BERNARD ROUSSEAU
Affiliation:
Dynamique et Photoregulation des Membranes Végétales, URA CNRS 1810, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris Cedex 05, France
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Abstract

Two brown algae, Pelvetia canaliculata and Laminaria saccharina, from the higher and lower mediolittoral belts respectively, have been tested for their capacity to overcome high-light stress in water and in air (in both fully hydrated and desiccated states). When exposed to supersaturating light irradiance in water, the two species developed non-photochemical quenching of fluorescence (NPQ) which was correlated with an increase in the de-epoxidation ratio (DR) of the xanthophyll cycle carotenoids (violaxanthin, antheraxanthin and zeaxanthin) and was followed by a slower decrease in oxygen evolution. NPQ reached values of up to 9 in P. canaliculata but only 4·5 in L. saccharina, at DRs of 0·65 and 0·5, respectively. In air, the xanthophyll cycle was also operative but the efficiency of de-epoxidation decreased linearly with the degree of hydration of the thallus. Photoprotection capacities in air also appeared higher in P. canaliculata than in L. saccharina, probably due to the higher molar content of the xanthophyll cycle pool size relative to chlorophyll a (Chl a) in the former (nearly double of that L. saccharina at 19 carotenoid molecules per 100 Chl a), which may be associated with a higher DR at the same level of desiccation. The concomitant higher accumulation of zeaxanthin in P. canaliculata might divert a higher percentage of the incident energy from the reaction centres, as demonstrated by the levels of NPQ, with steady-state fluorescence reduced to below the initial F0 level. Such differences, together with the unequal resistance to desiccation of the operation of the xanthophyll cycle, should be considered as possible factors responsible for the distribution for these two species on the shore.

Type
Research Article
Copyright
© 1999 British Phycological Society

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