Abstract:
Contrary to the many whole genome duplication events recorded for angiosperms (flowering
plants), whole genome duplications in gymnosperms (non-flowering seed plants) seem to
be much rarer. Although ancient whole genome duplications have been reported for most
gymnosperm lineages as well, some are still contested and need to be confirmed. For
instance, data for ginkgo, but particularly cycads have remained inconclusive so far, likely
due to the quality of the data available and flaws in the analysis. We extracted and sequenced
RNA from both the cycad Encephalartos natalensis and Ginkgo biloba. This was
followed by transcriptome assembly, after which these data were used to build paralog age
distributions. Based on these distributions, we identified remnants of an ancient whole
genome duplication in both cycads and ginkgo. The most parsimonious explanation would
be that this whole genome duplication event was shared between both species and had
occurred prior to their divergence, about 300 million years ago.
