A single origin of the peridinin- and fucoxanthin-containing plastids in dinoflagellates through tertiary endosymbiosis

Abstract

The most widely distributed dinoflagellate plastid contains chlorophyll c 2 and peridinin as the major carotenoid. A second plastid type, found in taxa such as Karlodinium micrum and Karenia spp., contains chlorophylls c 1 ؉ c2 and 19 -hexanoyloxy-fucoxanthin and͞or 19 -butanoyloxy-fucoxanthin but lacks peridinin. Because the presence of chlorophylls c 1 ؉ c2 and fucoxanthin is typical of haptophyte algae, the second plastid type is believed to have originated from a haptophyte tertiary endosymbiosis in an ancestral peridinin-containing dinoflagellate. This hypothesis has, however, never been thoroughly tested in plastid trees that contain genes from both peridinin-and fucoxanthin-containing dinoflagellates. To address this issue, we sequenced the plastid-encoded psaA (photosystem I P700 chlorophyll a apoprotein A1), psbA (photosystem II reaction center protein D1), and ''Form I'' rbcL (ribulose-1,5-bisphosphate carboxylase͞oxygenase) genes from various red and dinoflagellate algae. The combined psaA ؉ psbA tree shows significant support for the monophyly of peridinin-and fucoxanthin-containing dinoflagellates as sister to the haptophytes. The monophyly with haptophytes is robustly recovered in the psbA phylogeny in which we increased the sampling of dinoflagellates to 14 species. As expected from previous analyses, the fucoxanthin-containing dinoflagellates formed a wellsupported sister group with haptophytes in the rbcL tree. Based on these analyses, we postulate that the plastid of peridinin-and fucoxanthin-containing dinoflagellates originated from a haptophyte tertiary endosymbiosis that occurred before the split of these lineages. Our findings imply that the presence of chlorophylls c 1 ؉ c2 and fucoxanthin, and the Form I rbcL gene are in fact the primitive (not derived, as widely believed) condition in dinoflagellates.

There is more to maerl than meets the eye: DNA barcoding reveals a new species in Britain, Lithothamnion erinaceum sp. nov. (Hapalidiales, Rhodophyta)

“…The type specimen of L. lemoineae was sequenced separately to avoid contamination. Two gene fragments were amplified: (1) a standard DNA barcode of 664 bp, the 5' mitochondrial end of the cytochrome oxidase 1 unit (CO1-5P), using primers M13LF3 and M13Rx (Saunders & Moore, 2013); and (2) a 950 bp barcode of the plastid Photosystem II thylakoid membrane protein (psbA), using primers psbAF1 and psbAR2 (Yoon et al, 2002). extension at 72 °C for 1 min; final extension at 72 °C for 7 min and final hold at 10 °C) (Saunders & Moore, 2013).…”

“…The plastid psbA gene can be seen as a viable alternative for routine DNA barcoding (Carro et al, 2014) and phylogenetic analysis (Bittner et al, 2011). As the psbA gene evolves more slowly than the mitochondrial CO1 gene, it is used to recover deep phylogenetic relationships (Yoon et al, 2002) and to resolve intrageneric relationships (Seo et al, 2003, ;Yang & Boo, 2004). The results of the initial barcoding study led to a phylogenetic analysis using historical and contemporary material of Lithothamnion around Britain, as well as an assessment of the disparity between molecular and morphological diversity.…”

Phylogeny and morphology of a Chattonella (Raphidophyceae) species from the Mediterranean Sea: what is C. subsalsa?

“…The PCR steps were a hold at 94°C for 9 min, followed by 20 cycles of 94°C for 30 s, 55°C for 30 s and 72°C for 9 m. For ITS, we used ITS A (5′-CCAAGCTTCTAGATCGTAACAAGGHT CCGTAGGT-3′) and ITS B (5′-CCTGCAGTCGACAKA TGCTTAARTTCAGCRGG-3′) (Adachi et al, 1996), with PCR steps comprising a hold at 94°C for 5 min, followed by 35 cycles of 94°C for 20 s, 57°C for 10 s and 70°C for 5 min. The primers for rbcL were 130F (5′-AACWACWACTTGG ATTTGGAA-3′) and 1600R (5′-GCATGAATATGMTG WACCAT-3′) (Yoon et al, 2002), with PCR steps comprising a hold at 94°C for 2 min, followed by 39 cycles of 94°C for 20 s, 46°C for 30 s and 70°C for 5 min. Finally, for amplifying psaA, the primers were F3 (5′-GCTTACCGTG TAGATCCAGTTCC-3′) and R3 (5′-CCTTCTAATTTA CCAACAACTG-3′) (Beszteri, 2005); PCR conditions were a hold at 94°C for 3 min, followed by 39 cycles of 94°C for 30 s, 44.5°C for 30 s, and 70°C for 5 min.…”

“…The sequencing reaction conditions were the same as for PCR. Additional primers were used for long sequences; for SSU these were 528F (5′-GCGGTAATTCCAGCTCC AA-3′), 1055F (5′-GGTGGTGCATGGCCGTTCTT-3′), 536R (5′-AATTACCGCGGCKGCTGGCA-3′) and 1055R (5′-ACGGCCATGCACCACCACCCAT-3′) (Scholin et al, 1994); and for psaA, 870F (5′-ggnggwytatggttaagtga-3′) (Yoon et al, 2002).…”

The Life History and Cell Cycle of Kryptoperidinium foliaceum, A Dinoflagellate with Two Eukaryotic Nuclei

“…Dinoflagellates are unique among eukaryotic algae in that they have taken the process of endosymbiosis one step further, since in several independent lineages the peridinin plastid has been replaced either with a successive secondary plastid or with a plastid from another secondary alga, resulting in tertiary plastids. Examples are the dinoflagellate groups of haptophyte (Karenia, Karlodinium, Takayama) (Yoon et al 2002), green algal (Lepidodinium) (Watanabe et al 1990), and diatom origin (Kryptoperidinium, Durinskia, Galeidinium, and Dinothrix as well as some species presently included in Peridinium [P. quinquecorne] and Gymnodinium [G. quadrilobatum]).The diatom endosymbiont is related to either centric (P. quinquecorne) (Horiguchi and Takano 2006) or pennate (Kryptoperidinium) (Chesnick et al 1996(Chesnick et al , 1997 groups. The tertiary endosymbiosis is more or less stable, depending on the dinoflagellate group, although knowledge of the symbiont-host system is limited, mainly restricted to genera such as Kryptoperidinium.…”