Data for: Euglenozoan kleptoplasty illuminates the early evolution of photoendosymbiosis

Kleptoplasts (kP) are distinct among photosynthetic organelles in
eukaryotes (i.e., plastids) because they are routinely sequestered from
prey algal cells and function only temporarily in the new host cell.
Therefore, the hosts of kleptoplasts benefit from photosynthesis without
constitutive photoendosymbiosis. Here, we report that the euglenozoan
Rapaza viridis has only kleptoplasts derived from a specific strain of
green alga, Tetraselmis sp., but no canonical plastids like those found in
its sister group, the Euglenophyceae. R. viridis showed a dynamic change
in the accumulation of cytosolic polysaccharides in response to light–dark
cycles, and 13 C isotopic labeling of ambient bicarbonate demonstrated
that these polysaccharides originate in situ via photosynthesis;
these data indicate that the kleptoplasts of R. viridis are functionally
active. We also identified 276 sequences encoding putative
plastid-targeting proteins and 35 sequences of presumed kleptoplast
transporters in the transcriptome of R. viridis . These genes originated
in a wide range of algae other than Tetraselmis sp., the source of the
kleptoplasts, suggesting a long history of repeated horizontal gene
transfer events from different algal prey cells. Many of the kleptoplast
proteins, as well as the protein-targeting system, in R. viridis were
shared with members of the Euglenophyceae, providing evidence that the
early evolutionary stages in the green alga-derived secondary plastids of
euglenophytes also involved kleptoplasty.