Sequencing the genomes of Saccharum spontaneum and Saccharum officinarum

The sugarcane genome is a large polyploid genome that poses some specific challenges to genome sequencing. The commercially important sugarcane hybrid is comprised of two genomes from the parents Saccharum officinarum and S. spontaneum. S. officinarum is a decaploid (x = 10) with 10 chromosomes and a genome size of 7 Gb (base genome size 1C = 930 Mb). In contrast, the S. spontaneum is 80% smaller and is an octaploid (x =8) with a genome size of 5 Gb (base genome size 1C = 750 Mb). The modern sugarcane hybrids or cultivars appear to have between 2n=100 and 2n=130 chromosomes, indicating that aneuploidy (i.e. the presence of a distinct number of the different categories of chromosomes) is common. Here I will describe efforts to sequence the s. officinarum and S. spontaneum parent genomes and how these genomes provide insights into building tools for the hybrid genome.