Phylogenetic relatedness, co-occurrence, and rhizomes increase lateral gene transfer among grasses 
Hibdige, et al., 2020

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.

Time-calibrated phylogenetic tree of 17 model grass species used in this study (extracted from Christin et al. 2014; scale in million years - Myr). The direction of LGT between grass clades is shown with arrows whose size is proportional to the number of LGT. The black portion of pie charts on key nodes of the phylogeny indicates the quartet support for the observed topology based on a multigene coalescence analysis. The size of each pie chart is proportional to the number of species within the clade.

https://www.biorxiv.org/content/10.1101/2020.02.17.952150v1 
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