Divinyl chlorophyll a in the marine eukaryotic protist A lexandrium ostenfeldii ( D inophyceae)

Summary Here it is reported the first detection of DV ‐chl a together with the usual chl a in the marine dinoflagellate A lexandrium ostenfeldii from the B altic S ea. Growth response and photosynthetic parameters were examined at two irradiances (80 and 240 μmol photons m −2  s −1 ) and temperatures (15°C and 19°C) in a divinylic strain ( AOTV ‐OS20) versus a monovinylic one ( AOTV ‐OS16), using in vivo chl a fluorescence kinetics of PSII to characterize photosynthetic parameters by pulse amplitude modulated fluorescence, 14 C assimilation rates and toxin analyses. The divinylic isolate exhibited slower growth and stronger sensitivity to high irradiance than normal chl a strain. DV ‐chl a  : chl a ratios decreased along time (from 11.3 to < 0.5 after 10 months) and to restore them sub‐cloning and selection of strains with highest DV ‐chl a content was required. A mutation and/or epigenetic changes in the expression of divinyl reductase gene/s in A. ostenfeldii may explain this altered pigment composition. Despite quite severe limitations (reduced fitness and gradual loss of DV ‐chl a content), the DV ‐chl a ‐containing line in A. ostenfeldii could provide a model organism in photosynthetic studies related with chl biosynthesis and evolution.