Photosynthetic light reactions comprise a significant source of hydrogen peroxide (H2O2) in illuminated leaves. APXs (ascorbate peroxidases) reduce H2O2 to water and play an important role in the antioxidant system of plants. In the present study we addressed the significance of chloroplast APXs in stress tolerance and signalling in Arabidopsis thaliana. To this end, T-DNA (transfer DNA) insertion mutants tapx, sapx and tapx sapx, lacking the tAPX (thylakoid-bound APX), sAPX (stromal APX) or both respectively, were characterized. Photo-oxidative stress during germination led to bleaching of chloroplasts in sapx single-mutant and particularly in the tapx sapx double-mutant plants, whereas the greening process of wild-type and tapx plants was only partially impaired. Mature leaves of tapx sapx double mutants were also susceptible to short-term photo-oxidative stress induced by high light or methyl viologen treatments. After a 2-week acclimation period under high light or under low temperature, none of the mutants exhibited enhanced stress symptoms. Immunoblot analysis revealed that high-light-stress-acclimated tapx sapx double mutants compensated for the absence of tAPX and sAPX by increasing the level of 2-cysteine peroxiredoxin. Furthermore, the absence of tAPX and sAPX induced alterations in the transcriptomic profile of tapx sapx double-mutant plants already under quite optimal growth conditions. We conclude that sAPX is particularly important for photoprotection during the early greening process. In mature leaves, tAPX and sAPX are functionally redundant, and crucial upon sudden onset of oxidative stress. Moreover, chloroplast APXs contribute to chloroplast retrograde signalling pathways upon slight fluctuations in the accumulation of H2O2 in chloroplasts.
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Research Article|
May 14 2008
Diverse roles for chloroplast stromal and thylakoid-bound ascorbate peroxidases in plant stress responses
Saijaliisa Kangasjärvi;
Saijaliisa Kangasjärvi
*Department of Biology, University of Turku, FI-20014 Turku, Finland
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Anna Lepistö;
Anna Lepistö
*Department of Biology, University of Turku, FI-20014 Turku, Finland
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Kati Hännikäinen;
Kati Hännikäinen
*Department of Biology, University of Turku, FI-20014 Turku, Finland
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Mirva Piippo;
Mirva Piippo
*Department of Biology, University of Turku, FI-20014 Turku, Finland
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Eeva-Maria Luomala;
Eeva-Maria Luomala
†Agrifood Research Finland, FI-21500 Piikkiö, Finland
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Eva-Mari Aro;
Eva-Mari Aro
*Department of Biology, University of Turku, FI-20014 Turku, Finland
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Eevi Rintamäki
Eevi Rintamäki
1
*Department of Biology, University of Turku, FI-20014 Turku, Finland
1To whom correspondence should be addressed (email evirin@utu.fi).
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Publisher: Portland Press Ltd
Received:
January 03 2008
Revision Received:
February 21 2008
Accepted:
February 28 2008
Accepted Manuscript online:
February 28 2008
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2008 Biochemical Society
2008
Biochem J (2008) 412 (2): 275–285.
Article history
Received:
January 03 2008
Revision Received:
February 21 2008
Accepted:
February 28 2008
Accepted Manuscript online:
February 28 2008
Citation
Saijaliisa Kangasjärvi, Anna Lepistö, Kati Hännikäinen, Mirva Piippo, Eeva-Maria Luomala, Eva-Mari Aro, Eevi Rintamäki; Diverse roles for chloroplast stromal and thylakoid-bound ascorbate peroxidases in plant stress responses. Biochem J 1 June 2008; 412 (2): 275–285. doi: https://doi.org/10.1042/BJ20080030
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