Assembly and annotation of a draft genome sequence for Glycine latifolia, a perennial wild relative of soybean.

Abstract

Glycine latifolia (Benth.) Newell & Hymowitz (2n=40), one of the 27 wild perennial relatives of soybean, possesses genetic diversity and agronomically favorable traits that are lacking in soybean. Here, we report the 939-Mb draft genome assembly of G.latifolia (PI 559298) using exclusively linked-reads sequenced from a single Chromium library. We organized scaffolds into 20 chromosome-scale pseudomolecules utilizing two genetic maps and the Glycine max (L.) Merr. genome sequence. High copy numbers of putative 91-bp centromere-specific tandem repeats were observed in consecutive blocks within predicted pericentromeric regions on several pseudomolecules. No 92-bp putative centromeric repeats, which are abundant in G.max, were detected in G.latifolia or Glycine tomentella. Annotation of the assembled genome and subsequent filtering yielded a high confidence gene set of 54475 protein-coding loci. In comparative analysis with five legume species, genes related to defense responses were significantly overrepresented in Glycine-specific orthologous gene families. A total of 304 putative nucleotide-binding site (NBS)-leucine-rich-repeat (LRR) genes were identified in this genome assembly. Different from other legume species, we observed a scarcity of TIR-NBS-LRR genes in G.latifolia. The G.latifolia genome was also predicted to contain genes encoding 367 LRR-receptor-like kinases, a family of proteins involved in basal defense responses and responses to abiotic stress. The genome sequence and annotation of G.latifolia provides a valuable source of alternative alleles and novel genes to facilitate soybean improvement. This study also highlights the efficacy and cost-effectiveness of the application of Chromium linked-reads in diploid plant genome de novo assembly.