Photoinhibition and zeaxanthin formation in intact leaves. A possible role of the xanthophyll cycle in the dissipation of excess light energy. [Populus balsamifera; Hedera; helix; Monstrosa deliciosa]

Journal Article · Fri May 01 04:00:00 EDT 1987 · Plant Physiol.; (United States)

OSTI ID:6060385

Demmig, B; Winter, K; Krueger, A; Czygan, F C

Comparative studies of chlorophyll a fluorescence, measured with a pulse amplitude modulated fluorometer, and of the pigment composition of leaves, suggest a specific role of zeaxanthin, a carotenoid formed in the xanthophyll cycle, in protecting the photosynthetic apparatus against the adverse effects of excessive light. This conclusion is based on the following findings: (a) exposure of leaves of Populus balsamifera, Hedera helix, and Monstera deliciosa to excess excitation energy (high light, air; weak light, 2% O/sub 2/, 0% CO/sub 2/) led to massive formation of zeaxanthin and a decrease in violaxanthin. (b) When exposed to photoinhibitory light levels in air, shade leaves of H. helix had a higher capacity for zeaxanthin formation, at the expense of ..beta..-carotene, than shade leaves of M. deliciosa. Changes in fluorescence characteristics suggested that, in H. helix, the predominant response to high light was an increase in the rate of nonradiative energy dissipation, whereas, in M. deliciosa, photoinhibitory damage to photosystem II reaction centers was the prevailing effect. (c) Exposure of a sun leaf of P. balsamifera to increasing photon flux densities in 2% O/sub 2/ and 0% CO/sub 2/ resulted initially in increasing levels of zeaxanthin (matched by decreases in violaxanthin) and was accompanied by fluorescence changes indicative of increased nonradiative energy dissipation. Above the light level at which no further increase in zeaxanthin content was observed, fluorescence characteristics indicated photoinhibitory damage. (d) A linear relationship was obtained between the ratio of variable to maximum fluorescence, F/sub V/F/sub M/, determined with the modulated fluorescence technique at room temperature, and the photon yield of O/sub 2/ evolution.

• Research Organization: Universitaet Wuerzburg, West Germany
• OSTI ID: 6060385
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 84:1; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

551000 -- Physiological Systems
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL EFFECTS
BIOLOGICAL FUNCTIONS
CARBOXYLIC ACIDS
CAROTENOIDS
CHEMICAL REACTIONS
CHLOROPHYLL
ELEMENTS
ENERGY LOSSES
FLUORESCENCE
FLUORIMETERS
FUNCTIONS
HEAT LOSSES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
LOSSES
LUMINESCENCE
MEASURING INSTRUMENTS
MEMBRANES
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORNAMENTAL PLANTS
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHOTOSYNTHETIC MEMBRANES
PHYSIOLOGY
PHYTOCHROMES
PIGMENTS
PLANTS
POPLARS
PORPHYRINS
PROTEINS
SYNTHESIS
TERPENES
TREES