The highly allo-autopolyploid modern sugarcane genome and very recent allopolyploidization in Saccharum.

Modern sugarcane, a highly allo-autopolyploid organism, has a very complex genome. In the present study, the karyotype and genome architecture of modern sugarcane were investigated, resulting in a genome assembly of 97 chromosomes (8.84 Gb). The allopolyploid genome was divided into subgenomes from Saccharum officinarum (So) and S. spontaneum (Ss), with So dominance in the Saccharum hybrid (S. hybrid). Genome shock affected transcriptome dynamics during allopolyploidization. Analysis of an inbreeding population with 192 individuals revealed the underlying genetic basis of transgressive segregation. Population genomics of 310 Saccharum accessions clarified the breeding history of modern sugarcane. Using the haplotype-resolved S. hybrid genome as a reference, genome-wide association studies identified a potential candidate gene for sugar content from S. spontaneum. These findings illuminate the complex genome evolution of allopolyploids, offering opportunities for genomic enhancements and innovative breeding strategies for sugarcane.