Document Detail

High-light stress and photoprotection in Umbilicaria antarctica monitored by chlorophyll fluorescence imaging and changes in zeaxanthin and glutathione.
MedLine Citation:
PMID:  15143442     Owner:  NLM     Status:  MEDLINE    
The effect of high light on spatial distribution of chlorophyll (Chl) fluorescence parameters over a lichen thallus (Umbilicaria antarctica) was investigated by imaging of Chl fluorescence parameters before and after exposure to high light (1500 micro mol m (-2) s (-1), 30 min at 5 degrees C). False colour images of F (V)/F (M) and Phi (II) distribution, taken over thallus with 0.1 mm (2) resolution, showed that maximum F (V)/F (M) and Phi (II) values were located close to the thallus centre. Minimum values were typical for thallus margins. After exposure to high light, a differential response of F (V)/F (M) and Phi (II) was found. The marginal thallus part exhibited a loss of photosynthetic activity, manifested as a lack of Chl fluorescence signal, and close-to-centre parts showed a different extent of F (V)/F (M) and Phi (II) decrease. Subsequent recovery in the dark led to a gradual return of F (V)/F (M) and Phi (II) to their initial values. Fast (30 min) and slow (1 - 22 h) phase of recovery were distinguished, suggesting a sufficient capacity of photoprotective mechanisms in U. antarctica to cope with low-temperature photoinhibition. Glutathione and xanthophyll cycle pigments were analyzed by HPLC. High light led to an increase in oxidized glutathione (GSSG), and a conversion of violaxanthin to zeaxanthin, expressed as their de-epoxidation state (DEPS). The responses of GSSG and DEPS were reversible during subsequent recovery in the dark. GSSG and DEPS were highly correlated to non-photochemical quenching (NPQ), indicating involvement of these antioxidants in the resistance of U. antarctica to high-light stress. Heterogeneity of Chl fluorescence parameters over the thallus and differential response to high light are discussed in relation to thallus anatomy and intrathalline distribution of the symbiotic alga Trebouxia sp.
M Barták; J Hájek; H Vráblíková; J Dubová
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Plant biology (Stuttgart, Germany)     Volume:  6     ISSN:  1435-8603     ISO Abbreviation:  Plant Biol (Stuttg)     Publication Date:  2004 May 
Date Detail:
Created Date:  2004-05-14     Completed Date:  2004-08-04     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  101148926     Medline TA:  Plant Biol (Stuttg)     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  333-41     Citation Subset:  IM    
Masaryk University, Faculty of Science, Department of Plant Physiology and Anatomy, Brno, Czech Republic.
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MeSH Terms
Acclimatization / radiation effects
Algae / growth & development
Chlorophyll / metabolism*
Cold Temperature
Fluorometry / methods
Glutathione / metabolism*
Lichens / cytology,  physiology*,  radiation effects
Photosynthetic Reaction Center Complex Proteins / physiology*,  radiation effects
beta Carotene / analogs & derivatives,  metabolism*
Reg. No./Substance:
0/Photosynthetic Reaction Center Complex Proteins; 0/Xanthophylls; 1406-65-1/Chlorophyll; 144-68-3/zeaxanthin; 70-18-8/Glutathione; 7235-40-7/beta Carotene

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