Lateral gene transfer generates accessory genes that accumulate at different rates within a grass lineage

<p><span></span></p> <p>Lateral gene transfer (LGT) is the <span>movement</span> of DNA between <span>organism</span> without sexual <span>reproduction. </span>The acquired genes represent genetic novelties that <span>have</span> independently evolved in the donor<span>'</span>s genome. <span>Phylogenetic</span> methods <span>have</span> shown that LGT is widespread across the entire grass family, although we know little about the underlying dynamics.</p> <p>We identify laterally acquired genes in five de novo reference genomes from the same grass genus (four <em>Alloteropsis semialata</em> and one <em>Alloteropsis angusta</em>). Using additional resequencing data for a further 40 Alloteropsis individuals, we place the acquisition of each gene onto a phylogeny using stochastic character mapping, and then infer rates of gains and losses.</p> <p>We detect 168 laterally acquired genes in the five reference genomes [32-100 per genome]. Exponential decay models indicate that the rate of LGT acquisitions [6-28 per Ma] and subsequent losses [11-24% per Ma] varied significantly among lineages. Laterally acquired genes were lost at a higher rate than vertically inherited loci [0.02-0.8% per Ma].</p> <p>This high turnover creates intraspecific gene content variation, with a preponderance of them occurring as accessory genes in the <em>Alloteropsis</em> pangenome. This rapid turnover generates standing variation that can ultimately fuel local adaptation.</p>