title: Single cell genome analysis supports a link between phagotrophy and primary plastid endosymbiosis.
abstract: Two cases of primary plastid endosymbiosis are known. The first occurred ca. 1.6 billion years ago and putatively gave rise to the canonical plastid in algae and plants. The second is restricted to a genus of rhizarian amoebae that includes Paulinella chromatophora. Photosynthetic Paulinella species gained their plastid from an α-cyanobacterial source and are sister to plastid-lacking phagotrophs such as Paulinella ovalis that ingest cyanobacteria. To study the role of feeding behavior in plastid origin, we analyzed single-cell genome assemblies from six P. ovalis-like cells isolated from Chesapeake Bay, USA. Dozens of contigs in these cell assemblies were derived from prey DNA of α-cyanobacterial origin and associated cyanophages. We found two examples of horizontal gene transfer (HGT) in P. ovalis-like nuclear DNA from cyanobacterial sources. This work suggests the first evidence of a link between feeding behavior in wild-caught cells, HGT, and plastid primary endosymbiosis in the monophyletic Paulinella lineage.
authors.forename: Debashish
authors.initials: D
authors.lastname: Bhattacharya
authors.forename: Dana C
authors.initials: DC
authors.lastname: Price
authors.forename: Hwan Su
authors.initials: HS
authors.lastname: Yoon
authors.forename: Eun Chan
authors.initials: EC
authors.lastname: Yang
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Poulton
authors.forename: Robert A
authors.initials: RA
authors.lastname: Andersen
authors.forename: Sushma Parankush
authors.initials: SP
authors.lastname: Das