Premium
Contrasting modes of inorganic carbon acquisition amongst Symbiodinium (Dinophyceae) phylotypes
Author(s) -
Brading Patrick,
Warner Mark E.,
Smith David J.,
Suggett David J.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12379
Subject(s) - symbiodinium , dinophyceae , total inorganic carbon , dinoflagellate , biology , phylotype , carbon fixation , rubisco , botany , ocean acidification , carbonic anhydrase , carbon dioxide in earth's atmosphere , symbiosis , ecology , photosynthesis , carbon dioxide , bacteria , phytoplankton , biochemistry , phylogenetics , gene , seawater , nutrient , genetics , enzyme
Summary Growing concerns over ocean acidification have highlighted the need to critically understand inorganic carbon acquisition and utilization in marine microalgae. Here, we contrast these characteristics for the first time between two genetically distinct dinoflagellate species of the genus Symbiodinium (phylotypes A13 and A20) that live in symbiosis with reef‐forming corals. Both phylotypes were grown in continuous cultures under identical environmental conditions. Rubisco was measured using quantitative Western blots, and radioisotopic 14 C uptake was used to characterize light‐ and total carbon dioxide (TCO 2 )‐dependent carbon fixation, as well as inorganic carbon species preference and external carbonic anhydrase activity. A13 and A20 exhibited similar rates of carbon fixation despite cellular concentrations of Rubisco being approximately four‐fold greater in A13. The uptake of CO 2 overHCO 3−was found to support the majority of carbon fixation in both phylotypes. However, A20 was also able to indirectly utilizeHCO 3−by first converting it to CO 2 via external carbonic anhydrase. These results show that adaptive differences in inorganic carbon acquisition have evolved within the Symbiodinium genus, which thus carries fundamental implications as to how this functionally key genus will respond to ocean acidification, but could also represent a key trait factor that influences their productivity when in hospite of their coral hosts.