Journal
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY
Volume 84, Issue 3, Pages 197-203Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jphotobiol.2006.03.004
Keywords
antioxidant; L-ascorbic acid; circadian; Euglena gracilis; midday; photooxidation; spinach
Categories
Ask authors/readers for more resources
Plant defenses against photo-oxidative stress have been studied almost exclusively with respect to stress responses, and little is known about how non-enzymic antioxidants change under constant conditions without a time cue or an environmental stress. Here, we show that, in both the flagellated alga Euglena gracilis Z and the angiosperm Spinacia oleracea L., the potent antioxidant L-ascorbic acid (Asc) displays a circadian rhythm with a maximum at subjective midday, a physiological state reflecting that attained at noon under daily light/dark cycles. Thus, photosynthetic organisms can maximize antioxidant levels in anticipation of midday, when photo-oxidative stress is most severe. These results may partly explain the in-phase circadian UV-C resistance rhythm recently identified in the alga. However, the Asc, but not the resistance, rhythm wanes in continuous darkness. This suggests the presence of persistent circadian rhythms in the levels of other antioxidants in continuous darkness, which may account for the UV-C resistance rhythm. (c) 2006 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available