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Senescence‐specific regulation of catalases in Arabidopsis thaliana (L.) Heynh
Author(s) -
ZIMMERMANN PETRA,
HEINLEIN CHRISTINA,
ORENDI GABRIELE,
ZENTGRAF ULRIKE
Publication year - 2006
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2005.01459.x
Subject(s) - catalase , senescence , peroxisome , peroxidase , chemistry , arabidopsis , arabidopsis thaliana , gene isoform , biochemistry , hydrogen peroxide , cytosol , carotenoid , enzyme , microbiology and biotechnology , biology , gene , mutant
Oxygen free radicals are thought to play an essential role in senescence, especially those derived from peroxisomes. Therefore, the activities of different isoforms of the peroxisomal hydrogen peroxide (H 2 O 2 )‐scavenging enzyme catalase (CAT) were analysed during senescence of Arabidopsis . CAT2 activity decreased with bolting time parallel with cytosolic ascorbate peroxidase 1 (APX1) activity before loss of chlorophyll could be measured. At the same time point, the H 2 O 2 content increased. Subsequently, the stress‐inducible CAT3 isoform was activated and APX1 activity was recovered, accompanied by a decline of the H 2 O 2 content. In very late stages, low activities of the seed‐specific CAT1 became detectable in leaves, but H 2 O 2 increased again. Further analyses of CAT expression by promoter : β ‐glucuronidase ( GUS ) fusions in transgenic plants revealed a vasculature‐specific CAT3 expression, whereas CAT2 expression turned out to be specific for photosynthetic active tissues. CAT2 expression is down‐regulated during leaf senescence, while CAT3 expression is induced with age and corresponds to an accumulation of H 2 O 2 in the vascular bundles. CAT2 down‐regulation on the transcriptional level appears as the initial step in creating the H 2 O 2 peak during bolting time, while the decrease in APX1 activity might only be a secondary and amplifying effect.