Photosynthesis Research

, Volume 107, Issue 3, pp 223–235

The interrelationship between the lower oxygen limit, chlorophyll fluorescence and the xanthophyll cycle in plants


    • Atlantic Food and Horticulture Research CentreAgriculture and Agri-Food Canada
    • Department of BiologyDalhousie University
  • John M. DeLong
    • Atlantic Food and Horticulture Research CentreAgriculture and Agri-Food Canada
  • Arunika H. L. A. N. Gunawardena
    • Department of BiologyDalhousie University
  • Robert K. Prange
    • Atlantic Food and Horticulture Research CentreAgriculture and Agri-Food Canada
Regular Paper

DOI: 10.1007/s11120-011-9621-9

Cite this article as:
Wright, A.H., DeLong, J.M., Gunawardena, A.H.L.A.N. et al. Photosynth Res (2011) 107: 223. doi:10.1007/s11120-011-9621-9


The lower oxygen limit (LOL) in plants may be identified through the measure of respiratory gases [i.e. the anaerobic compensation point (ACP) or the respiratory quotient breakpoint (RQB)], but recent work shows it may also be identified by a sudden rise in dark minimum fluorescence (Fo). The interrelationship between aerobic respiration and fermentative metabolism, which occur in the mitochondria and cytosol, respectively, and fluorescence, which emanates from the chloroplasts, is not well documented in the literature. Using spinach (Spinacia oleracea), this study showed that Fo and photochemical quenching (qP) remained relatively unchanged until O2 levels dropped below the LOL. An over-reduction of the plastoquinone (PQ) pool is believed to increase Fo under dark + anoxic conditions. It is proposed that excess cytosolic reductant due to inhibition of the mitochondria’s cytochrome oxidase under low-O2, may be the primary reductant source. The maximum fluorescence (Fm) is largely unaffected by low-O2 in the dark, but was severely quenched, mirroring changes to the xanthophyll de-epoxidation state (DEPS), under even low-intensity light (≈4 μmol m−2 s−1). In low light, the low-O2-induced increase in Fo was also quenched, likely by non-photochemical and photochemical means. The degree of quenching in the light was negatively correlated with the level of ethanol fermentation in the dark. A discussion detailing the possible roles of cyclic electron flow, the xanthophyll cycle, chlororespiration and a pathway we termed ‘chlorofermentation’ were used to interpret fluorescence phenomena of both spinach and apple (Malus domestica) over a range of atmospheric conditions under both dark and low-light.


ChlorofermentationChlororespirationFermentationNon-photochemical quenchingPhotochemical quenchingXanthophyll cycle

Supplementary material

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Supplementary material 1 (PPT 2597 kb)
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Supplementary material 2 (PPT 748 kb)
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Supplementary material 3 (TIFF 2666 kb)

Copyright information

© Her Majesty the Queen in Right of Canada 2011