Data from: Horizontal transfer of an adaptive chimeric photoreceptor from bryophytes to ferns

Ferns are well known for their shade-dwelling habits. Their ability to
thrive under low-light conditions has been linked to the evolution of a
novel chimeric photoreceptor—neochrome—that fuses red-sensing phytochrome
and blue-sensing phototropin modules into a single gene, thereby
optimizing phototropic responses. Despite being implicated in facilitating
the diversification of modern ferns, the origin of neochrome has remained
a mystery. We present evidence for neochrome in hornworts (a bryophyte
lineage) and demonstrate that ferns acquired neochrome from hornworts via
horizontal gene transfer (HGT). Fern neochromes are nested within hornwort
neochromes in our large-scale phylogenetic reconstructions of phototropin
and phytochrome gene families. Divergence date estimates further support
the HGT hypothesis, with fern and hornwort neochromes diverging 179 Mya,
long after the split between the two plant lineages (at least 400 Mya). By
analyzing the draft genome of the hornwort Anthoceros punctatus, we also
discovered a previously unidentified phototropin gene that likely
represents the ancestral lineage of the neochrome phototropin module.
Thus, a neochrome originating in hornworts was transferred horizontally to
ferns, where it may have played a significant role in the diversification
of modern ferns.