Progress on the Genome Characterisation of the Sydney Rock Oyster Saccostrea glomerata

The Sydney Rock oyster Saccostrea glomerata is endemic to Australia and New Zealand and, like the more common Pacific oyster, is considered a delicacy in restaurants around the world. For over a century, oyster farming has been the most valuable aquaculture industry in the state of New South Wales, Australia, where production of S. glomerata reached over AUD$34 million for 2014/2015. Pressures from disease and environmental stress are major challenges to oyster culture and, like many shellfish, the molecular mechanisms underpinning responses to these burdens have yet to be uncovered. Here we present a draft of an estimated 0.8 Gb haploid genome using approximately 300X coverage of illumina small insert paired-end libraries and three mate-pair libraries of 3, 6 and 10 Kb in size. Generation of a Chicago library and HiRise scaffolding from Dovetail Genomics was undertaken to overcome high levels of repetitiveness. The draft assembly has a total sequence length of 788 Mb, a scaffold number of 10,108 with an N50 of 804 Kb. More than 94 % of the assembly resides in scaffolds larger than 50 Kb and over 70 % of reads from six stranded RNA-Seq libraries mapped to the assembly. Ongoing efforts include refining gene models using previously generated transcriptome data. The draft genome will serve as a platform for genetic breeding programs, facilitating further research to improve important traits such as disease resistance, growth and reproductive performance.