Data from: Comparative transcriptomics revealed parallel evolution and innovation of photosymbiosis molecular mechanisms in a marine bivalve

Photosymbioses between heterotrophic hosts and autotrophic symbionts are
evolutionarily prevalent and ecologically significant. However, molecular
mechanisms behind such symbioses remain less elucidated, which hinders our
understanding of their origin and adaptive evolution. This study compared
gene expression patterns in a photosymbiotic bivalve (Fragum sueziense)
and a closely related non-symbiotic species (Trigoniocardia granifera)
under different light conditions to detect potential molecular pathways
involved in mollusk photosymbiosis. We discovered that the presence of
algal symbionts greatly impacted host gene expression in
symbiont-containing tissues. We found that the host immune functions were
suppressed under normal light compared to those in the dark. In addition,
we found that cilia in the symbiont-containing tissues play important
roles in symbiont regulation or photoreception. Interestingly, many
potential photosymbiosis genes could not be annotated or do not exhibit
orthologs in T. granifera transcriptomes, indicating unique molecular
functions in photosymbiotic bivalves. Overall, we found both novel and
known molecular mechanisms involved in animal-algal photosymbiosis within
bivalves. Given that many of the molecular pathways are shared among
distantly related host lineages, such as mollusks and cnidarians, it
indicates that parallel and/or convergent evolution is instrumental in
driving host-symbiont adaptations in diverse organisms.