The gymnosperm Welwitschia mirabilis belongs to the ancient, enigmatic gnetophyte lineage. It is a unique desert plant with extreme longevity and two ever-elongating leaves. We present a chromosome-level assembly of its genome (6.8 Gb/1 C) together with methylome and transcriptome data to explore its astonishing biology. We also present a refined, high-quality assembly of Gnetum montanum to enhance our understanding of gnetophyte genome evolution. The Welwitschia genome has been shaped by a lineage-specific ancient, whole genome duplication (~86 million years ago) and more recently (1-2 million years) by bursts of retrotransposon activity. High levels of cytosine methylation (particularly at CHH motifs) are associated with retrotransposons, whilst long-term deamination has resulted in an exceptionally GC-poor genome. Changes in copy number and/or expression of gene families and transcription factors (e.g. R2R3MYB, SAUR) controlling cell growth, differentiation and metabolism underpin the plant’s longevity and tolerance to temperature, nutrient and water stress.
Wan, T., Liu, Z., Leitch, I.J. et al.
CC BY 4.0
<p><a rel="nofollow" class="external free" href="https://www.nature.com/articles/s41467-021-24528-4">https://www.nature.com/articles/s41467-021-24528-4</a>
</p>
<a rel="nofollow" class="external free" href="https://doi.org/10.1038/s41467-021-24528-4">https://doi.org/10.1038/s41467-021-24528-4</a>