Single cell genomics of uncultured marine alveolates shows paraphyly of basal dinoflagellates

Abstract

Marine alveolates (MALVs) are diverse and widespread early-branching dinoflagellates, but most knowledge of the group comes from a few cultured species that are generally not abundant in natural samples, or from diversity analyses of PCR-based environmental SSU rRNA gene sequences. To more broadly examine MALV genomes, we generated single cell genome sequences from seven individually isolated cells. Genes expected of heterotrophic eukaryotes were found, with interesting exceptions like presence of proteorhodopsin and vacuolar H-pyrophosphatase. Phylogenetic analysis of concatenated SSU and LSU rRNA gene sequences provided strong support for the paraphyly of MALV lineages. Dinoflagellate viral nucleoproteins were found only in MALV groups that branched as sister to dinokaryotes. Our findings indicate that multiple independent origins of several characteristics early in dinoflagellate evolution, such as a parasitic life style, underlie the environmental diversity of MALVs, and suggest they have more varied trophic modes than previously thought.

Transcriptome of Thalassicolla nucleata Holobiont Reveals Details of a Radiolarian Symbiotic Relationship

“…Besides photosynthetic symbionts, heterotrophic protists (parasites) can also be found in radiolarian species. The most commonly observed parasites belong to marine alveolates Syndiniales, such as Merodinium, Solenodinium, and Syndinium (Anderson, 1983;Coats, 1999;Dolven et al, 2007).…”

Characterising planktonic dinoflagellate diversity in Singapore using DNA metabarcoding

“…While this and previous studies (e.g. Guillou et al 2008;Leong et al 2015) find Syndiniales to be monophyletic, as a whole, it may be paraphyletic (Strassert et al 2018). Syndiniales are obligate parasites found throughout marine habitats from the water surface to sediments and are often highly represented in environmental samples .…”

Phylogeny, evidence for a cryptic plastid, and distribution of Chytriodinium parasites (Dinophyceae) infecting copepods

“…Seawater was sampled from 60 m depth with Niskin bottles mounted on a rosette sampler in October 2014 in Monterey Bay (coordinates: 36°47'44.9" N, 121°50'47.4" W; for more details, see Strassert et al 2018). Four sporocytes released from a copepod-attached cyst were manually isolated using micro-capillaries.…”

“…With exception of the genome assembly, the procedures were generally conducted as described elsewhere (Strassert et al 2018). In short: the sequence data of the four samples (showing nearly identical SSU rRNA gene sequences) was pooled and FastQC (Andrews 2010) was used to evaluate the data quality.…”