Photosynthetic pigments in 37 species (65 strains) of Haptophyta: Implications for oceanography and chemotaxonomy

Abstract

The pigment compositions of 37 species (65 strains) of cultured haptophytes were analysed using improved HPLC methods. We distinguished 8 pigment types based on the distribution of 9 chlorophyll c (chl c) pigments and 5 fucoxanthin derivatives. All types contained chl c2 and Mg-2,4-divinyl phaeoporphyrin a5 monomethyl ester (MgDVP), fucoxanthin, diadinoxanthin and β,β-carotene. Pigment types were based on the following additional pigments: Type 1: chl c1; Type 2: chl c 1 and chl c2-Pavlova gyrans-type-, Type 3: chl c 1 and chl c2-monogalactosyl diacylglyceride ester (chl c2-MGDG [18:4/14:0]); Type 4: chl c1, chl c3 and non-polar chl c1-like; Type 5: chl c1, chl c 3, chl c2-MGDG [18:4/14:0] and 4-keto-fucoxanthin; Type 6: chl c3, monovinyl chl c3 (MV-chl c3), chl c2-MGDG [18:4/14:0], 19′-hexanoyloxyfucoxanthin and its 4-keto derivative, and traces of 19′-butanoyloxyfucoxanthin; Type 7: similar to Type 6, minus MV-chl c3 but with chl c2-MGDG [14:0/14:0] added; Type 8: similar to Type 6, minus MV-chl c3 but with significant 19′-butanoyloxyfucoxanthin. Taxonomic associations ranged from single genera to multiple families - Type 1: Pavlovaceae, Isochrysidaceae and Pleurochrysidaceae; Type 2: Pavlovaceae; Type 3: Isochrysidaceae; Type 4: Prymnesium spp.; Type 5: Ochrosphaera spp.; Type 6: Nöelaerhabdaceae, notably Emiliania spp.; Type 7: Chrysochromulina spp.; Type 8: Phaeocystaceae, Prymnesiaceae and Isochrysidaceae. These pigment types showed a strong correlation with available phylogenetic trees, supporting a genetic basis for the pigment associations. The additional marker pigments offer oceanographers greater power for detecting haptophytes in mixed populations, while also distinguishing a greater proportion of them from diatoms.