Acta Physiologiae Plantarum

, Volume 28, Issue 2, pp 127–136

Adaptation of the photosynthetic apparatus of Nitellopsis obtusa to changing light intensity at the molecular level: different pathways of a singlet excitation quenching

  • Wiesław I. Gruszecki
  • Małgorzata Gospodarek
  • Anna Ja kowska
  • Edward piewla
Article

DOI: 10.1007/s11738-006-0039-5

Cite this article as:
Gruszecki, W.I., Gospodarek, M., Ja kowska, A. et al. Acta Physiol Plant (2006) 28: 127. doi:10.1007/s11738-006-0039-5

Abstract

The effect of prolonged illumination (60 min) with photosynthetically active monochromatic radiation of low intensity (3 µmol m−2 s−1) and high intensity (60 µmol m−2 s−1), corresponding to the physiological conditions and light stress conditions, respectively, was studied in the algae Nitellopsis obtusa. Illumination of Nitellopsis obtusa cells with strong light was associated with activation of the xanthophyll cycle, manifested by the deepoxidation of violaxanthin and accumulation of antheraxanthin and zeaxanthin. At the same time, the efficient singlet excitation quenching in the photosynthetic apparatus was activated, as demonstrated by the decrease in the intensity of the chlorophyll a fluorescence emission by ca 50 %. The difference of the fluorescence excitation spectra recorded before and after the light treatment match the difference absorption spectrum of the xanthophyll cycle pigments. The illumination with low light intensity resulted also in the chlorophyll a fluorescence quenching but the effect was very small (less than 10 %). The fluorescence quenching is interpreted in terms of the energy transfer between the Qy energy level of chlorophyll a and the 21 Ag energy level of zeaxanthin. The singlet energy levels of carotenoids, corresponding to the green spectral region, are also taken into consideration in the interpretation of the excitation energy exchange between the carotenoids and chlorophylls. Possible molecular mechanisms involved in the activation of the strong and the weak excitation quenching, including violaxanthin isomerization, and possible physiological functions of such pathways of energy transfer are discussed.

Key words

Nitellopsis obtusa photosynthesis carotenoids xanthophylls cycle violaxanthin zeaxanthin light stress algae 

Copyright information

© Department of Plant Physiology 2009

Authors and Affiliations

  • Wiesław I. Gruszecki
    • 1
  • Małgorzata Gospodarek
    • 2
  • Anna Ja kowska
    • 2
  • Edward piewla
    • 2
  1. 1.Department of Biophysics, Institute of PhysicsMaria Curie-Skłodowska UniversityLublinPoland
  2. 2.Department of General Physics, Institute of PhysicsLublin Technical UniversityLublinPoland

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