Operation of the xanthophyll cycle in the seagrass Zostera marina in response to variable irradiance |
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| Authors: | PJ Ralph SM PolkKA Moore RJ OrthWO Smith Jr |
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| Institution: | a Institute for Water and Environmental Resource Management, University of Technology, Sydney, Westbourne St. Gore Hill, Sydney, NSW 2065, Australia
b Virginia Institute of Marine Sciences, School of Marine Sciences, College of William and Mary, Gloucester Point, Williamsburg, VA, 23602, USA |
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| Abstract: | Changes in the photobiology and photosynthetic pigments of the seagrass Zostera marina from Chesapeake Bay (USA) were examined under a range of natural and manipulated irradiance regimes. Photosynthetic activity was assessed using chlorophyll-a fluorescence, and photosynthetic pigments were measured by HPLC. Large changes in the violaxanthin, zeaxanthin, and antheraxanthin content were concomitant with the modulation of non-photochemical quenching (NPQ). Photokinetics (Fv/Fm, rapid light curves (RLC), and non-photochemical quenching) varied as a result of oscillating irradiance and were highly correlated to xanthophyll pigment content. Zeaxanthin and antheraxanthin concentrations increased under elevated light conditions, while violaxanthin increased in darkened conditions. Unusually high concentrations of antheraxanthin were found in Z. marina under a wide range of light conditions, and this was associated with the partial conversion of violaxanthin to zeaxanthin. These results support the idea that xanthophyll intermediate pigments induce a photoprotective response during exposure to high irradiances in this seagrass. |
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| Keywords: | Carotenoids Xanthophyll Non-photochemical quenching Chlorophyll-a fluorescence Light stress |
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