Pigment-based chloroplast types in dinoflagellates

Most photosynthetic dinoflagellates contain a chloroplast with peridinin as the major carotenoid. Chloroplasts from other algal lineages have been reported, suggesting multiple plastid losses and replacements through endosymbiotic events. The pigment composition of 64 dinoflagellate species (122 strains) was analysed by using high-performance liquid chromatography. In addition to chlorophyll (chl) a, both chl c(2) and divinyl protochlorophyllide occurred in chl c-containing species. Chl c(1) co-occurred with chl c(2) in some peridinin-containing (e. g. Gambierdiscus spp.) and fucoxanthin-containing dinoflagellates (e. g. Kryptoperidinium foliaceum). Chl c(3) occurred in dinoflagellates whose plastids contained 19'-acyloxyfucoxanthins (e. g. Karenia mikimotoi). Chl b was present in green dinoflagellates (Lepidodinium chlorophorum). Based on unique combinations of chlorophylls and carotenoids, 6 pigment-based chloroplast types were defined: Type 1: peridinin/dinoxanthin/chl c(2) (Alexandrium minutum); Type 2: fucoxanthin/19'-acyloxy fucoxanthins/4-keto-19'-acyloxy-fucoxanthins/gyroxanthin diesters/chl c(2), c(3), mono- galactosyl-diacylglycerol-chl c(2) (Karenia mikimotoi); Type 3: fucoxanthin/19'-acyloxyfucoxanthins/gyroxanthin diesters/chl c(2), c(3) (Karlodinium veneficum); Type 4: fucoxanthin/chl c(1), c(2) (K. foliaceum); Type 5: alloxanthin/chl c(2)/phycobiliproteins (Dinophysis tripos); Type 6: neoxanthin/violaxanthin/a major unknown carotenoid/chl b (Lepidodinium chlorophorum). While plastids with peridinin, and probably those with chl b, originated by secondary endosymbiosis, the other chloroplast types were obtained through tertiary endosymbiosis. Chloroplast types corresponded with evolutionary lineages within dinoflagellates. Caution must be observed when only peridinin is used for tracking photosynthetic dinoflagellates in field samples. The additional marker pigments offer oceanographers greater power for detecting dinophytes in mixed populations.