Planta

, Volume 223, Issue 3, pp 407–417

Thallus morphology and optical characteristics affect growth and DNA damage by UV radiation in juvenile Arctic Laminaria sporophytes

  • Michael Y. Roleda
  • Christian Wiencke
  • Dieter Hanelt
Original Article

DOI: 10.1007/s00425-005-0092-0

Cite this article as:
Roleda, M.Y., Wiencke, C. & Hanelt, D. Planta (2006) 223: 407. doi:10.1007/s00425-005-0092-0

Abstract

Growth of young sporophytes of the brown algae Laminaria digitata, L. saccharina and L. solidungula from Spitsbergen were measured in the laboratory after being exposed for 21 days to either photosynthetically active radiation (PAR=P) or to full light spectrum (PAR + UV-A + UV-B=PAB) using of cutoff glass filters. The plants were grown at 8±2°C and 16 h light : 8 h dark cycles with 6 h additional ultraviolet radiation (UVR) exposure in the middle of the light period. Growth was measured every 10 min using growth chambers with online video measuring technique. Tissue morphology and absorption spectra were measured in untreated young sporophytes while chlorophyll (Chl) a content and DNA damage were measured in treated thalli at the end of the experiment. In all species, growth rates were significantly higher in sporophytes exposed to P alone compared to sporophytes exposed to PAB. Tissue DNA damage is dependent on thallus thickness and absorption spectra characteristics of pigments and UV-absorbing compounds. In sporophytes exposed to UVR, energy demands for repair of DNA damage and synthesis of UV-absorbing compounds for protection effectively diverts photosynthate at the expense of growth. Photosynthetic pigment was not significantly different between treatments suggesting a capacity for acclimation to moderate UVR fluence. The general growth pattern in sporophytes exposed to P alone showed an increasing growth rate from the onset of light (0500–0900 hours) to a peak at the middle of the light phase (0900–1500 hours), a decline towards the end of the light phase (1500–2100 hours) and a minimum “low” growth in the dark (2100–0500 hours) relative to growth during the entire light phase. Under PAB, different growth patterns were observed such as growth compensation at night in L. digitata, delayed growth recovery in L. saccharina and minimal but continuous growth in L. solidungula. Growth as an integrative parameter of all physiological processes showed that the effect of UVR is correlated to the depth distribution of these species.

Keywords

Cyclobutane pyrimidine dimers (CPDs) Growth Laminaria digitata Laminaria saccharina Laminaria solidungula Pigments 

Abbreviations

PAR

Photosynthetically active radiation

UV-A

Ultraviolet-A

UV-B

Ultraviolet-B

UVR

UV radiation

P

PAR

PAB

PAR + UV-A + UV-B

PFD

Photon flux density

Chl

Chlorophyll

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Michael Y. Roleda
    • 1
    • 2
  • Christian Wiencke
    • 3
  • Dieter Hanelt
    • 4
  1. 1.Alfred Wegener Institute for Polar and Marine ResearchBiologische Anstalt HelgolandHelgolandGermany
  2. 2.Biology DepartmentDe La Salle UniversityManilaPhilippines
  3. 3.Foundation Alfred Wegener Institute for Polar and Marine ResearchBremerhavenGermany
  4. 4.Biozentrum Klein FlottbekUniversity of HamburgHamburgGermany

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