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NPQ activation reduces chlorophyll triplet state formation in the moss Physcomitrella patens.
MedLine Citation:
PMID:  22634338     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Plants live in variable environments in which light intensity can rapidly change, from limiting to excess conditions. Non-Photochemical Quenching (NPQ) is a regulatory mechanism which protects plants from oxidative stress by dissipating excess Chl singlet excitation. In this work, the physiological role of NPQ was assessed by monitoring its influence on the population of the direct source of light excess damage, i.e., Chl triplets ((3)Chl*). (3)Chl* formation was evaluated in vivo, with the moss Physcomitrella patens, by exploiting the high sensitivity of fluorescence-detected magnetic resonance (FDMR). A dark adapted sample was compared with a pre-illuminated sample in which NPQ was activated, the latter showing a strong reduction in (3)Chl*yield. In line with this result, mutants unable to activate NPQ showed only a minor effect in (3)Chl* yield upon pre-illumination. The decrease in (3)Chl*yield is equally experienced by all the Chl pools associated to PS II, suggesting that NPQ is effective in protecting both the core and the peripheral antenna complexes. Moreover, the FDMR results show that the structural reorganization in the photosynthetic apparatus, required by NPQ, does not lead to the formation of new (3)Chl* traps in the LHCs. This work demonstrates that NPQ activation leads to effective photoprotection, promoting a Photosystem II state characterized by a reduced probability of (3)Chl* formation, due to a decreased singlet excited state population, while maintaining an efficient quenching of the (3)Chl*eventually formed by carotenoids.
Authors:
Donatella Carbonera; Caterina Gerotto; Bianca Posocco; Giorgio Mario Giacometti; Tomas Morosinotto
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-5-23
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  -     ISSN:  0006-3002     ISO Abbreviation:  -     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-5-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier B.V.
Affiliation:
Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy.
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