Sequencing the Branches of the Eucalypt Tree: Comparison Between Eucalyptus and Corymbia Genomes

Corymbia, a closely related genus to Eucalyptus, has become an important forestry resource in the past few decades, grown for timber, essential oils and bioenergy applications. The spotted gum variety (C. citriodora subsp. variegata; CCV) and interspecific hybrids have been deployed globally in Australia, India, China and Brazil. Given its wide distribution and ecological and economic importance, the Corymbia genome consortium has sequenced and assembled two CCV genomes from genotypes that are representative of separate genepools within the natural population, both used in germplasm management and improvement. The genomes presented are a result of combining multiple assembly strategies using Illumina and PacBio technologies, combined with a high-density DArT-Seq genetic map to generate chromosome level assemblies. We assess assembly quality using single copy genes from the Eucalyptus grandis reference genome, along with macrosynteny and major structural variations across the 11 chromosomes. Additionally, the sequencing of this complex, heterozygous diploid allows investigation of biologically relevant questions in regard to the dynamic evolutionary history of Corymbia, as provided by evidence of specific tandem gene expansion events.