Figure 1

Use of optical mapping in theMedicago truncatulagenome assembly Mt4.0. Scaffolds assembled from next-generation sequencing were aligned against the Medicago optical map (OM_Chr4) in order to build a pseudo-chromosome. Scaffold0005 was identified as a chimeric scaffold with its left part aligned to the optical map while the right part aligned to a different chromosome. Optical mapping provided an independent line of evidence to join adjacent scaffolds and split misassembled sequences during the reconstruction of chromosomal-sized sequences.