A chromosome-scale assembly of the quinoa genome provides insights into the structure and dynamics of its subgenomes

<p>Quinoa (<em>Chenopodium</em> <em>quinoa</em> Willd.) is an allotetraploid seed crop with the potential to help address global food security concerns. Genomes have been assembled for three accessions of quinoa; however, all assemblies are fragmented and do not reflect known chromosome biology. Here, we used in vitro and in vivo Hi-C data to produce a chromosome-scale assembly of the Chilean quinoa accession PI 614886 (QQ74). The final assembly spanned 1.326 Gb, of which 90.5% was assembled into 18 chromosome-scale scaffolds. The genome was annotated with 54,499 protein-coding genes, 97% of which were located on the 18 largest scaffolds. We also produced an updated genome assembly for the B-genome diploid <em>C. suecicum</em> and used it, together with the A-genome diploid<em> C. pallidicaule</em>, to identify genomic rearrangements within the quinoa genome, including a large pericentromeric inversion representing 71.7% of chromosome Cq3B. Repetitive sequences comprise 65.20%, 48.61%, and 57.91% of the quinoa, <em>C. pallidicaule</em>, and <em>C. suecicum</em> genomes, respectively. Evidence suggests that the B subgenome is more dynamic and has expanded more than the A subgenome. These genomic resources will enable more accurate assessments of genome evolution within the Amaranthaceae and will facilitate future efforts to identify variation in genes underlying important agronomic traits in quinoa.</p>