Abstract
Background: Lateral gene transfer (LGT) has been documented in a broad range of eukaryotes, where it can promote adaptation. In plants, LGT of functional nuclear genes has been repeatedly reported in parasitic plants, ferns and grasses, but the exact extent of the phenomenon remains unknown. Systematic studies are now needed to identify the factors that govern the frequency of LGT among plants. Results: Here we scan the genomes of a diverse set of grass species that span more than 50 million years of divergence and include major crops. We identify protein coding LGT in a majority of them (13 out of 17). There is variation among species in the amount of LGT received, with rhizomatous species receiving more genes. In addition, the amount of LGT increases with phylogenetic relatedness, which might reflect genomic compatibility among close relatives facilitating successful transfers. However, we also observe genetic exchanges among distantly related species that diverged shortly after the origin of the grass family when they co-occur in the wild, pointing to a role of biogeography. The dynamics of successful LGT in grasses therefore appear to be dependent on both opportunity (co-occurrence and rhizomes) and compatibility (phylogenetic distance). Conclusion: Overall, we show that LGT is a widespread phenomenon in grasses, which is boosted by repeated contact among related lineages. The process has moved functional genes across the entire grass family into domesticated and wild species alike.
Phylogenetic relatedness, co-occurrence, and rhizomes increase lateral gene transfer among grasses (Pre-print, not peer reviewed)
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