Anatomical Differentiation and Photosynthetic Adaptation in Brown Algae

doi:2005.20.3.233

Algae > Volume 20(3); 2005 > Article

Algae 2005;20(3): 233-238. doi: https://doi.org/10.4490/algae.2005.20.3.233

David J. Garbary and Kwang Young Kim¹^*

Department of Biology, St. Francis Xavier University, Antigonish, Nova Scotia, B2G 2W5, Canada
¹Department of Oceanography, Chonnam National University, Gwangju 500-757, Korea

ABSTRACT

The photosynthetic parameters of dark- adapted minimum fluorescence (Fo) and maximum quantum yield of charge separation in PSII (Fv/Fm) were measured in transverse sections of eight species of marine Phaeophyceae (species of Laminariales, Fucales, Desmarestiales, Chordariales) using pulse amplified modulation (PAM) fluorometry. Within each transverse section fluorescence was measured in three regions corresponding to outer cortical and meristoderm cells, inner cortical cells and innermost medullary cells. Minimum fluorescence declined from 19-74% (mean of 39%) from outermost to innermost cells. Maximum quantum yield varied from 0.51-0.59 in outermost cell layers and this was reduced to 0.23-0.40 in innermost cell layers, with an average reduction of 50%. Despite the reduction Fo in medullary cells (inner), medullas of all species showed maximum quantum yields consistent with a photosynthetic role in carbon fixation. These results show that medullary cells of complex brown algae have more than a role in structure, storage or transport, and may also provide an important role in carbon fixation.

Key words: anatomy, brown algae, medullas, PAM, Phaeophyceae, photosynthesis