Saccharum officinarum Genome sequencing and assembly

Sugarcane is the primary sugar crop. Saccharum officinarum accounts for eighty to ninety percent of the genome in modern interspecific hybrid cultivars. Sequencing the LA Purple genome resulted in the assembly of 80 haplotype-resolved chromosomes in ten homologous groups with 39,355 allele-defined genes. No significant allelic dominance was detected among alleles in each of the ten homologous groups. Female restitution is 2n1 + n2, not 2n + n as previously proposed, in F1 and BC1 generations of S. officinarum S. spontaneum crosses. The doubling of female S. officinarum gamete chromosomes occurred between 2 - 20 hours after pollination. S. officinarum is strictly autooctoploid (2n = 8x = 80) with a prevalence of male sterility as the consequences of domestication and clonal cultivation. Balancing selection is a major force for domestication of this autooctoploid sugar crop. This autooctoploid genome yielded fundamental knowledge of sugarcane biology with profound implications for sugarcane improvement.