Chromosome painting in cultivated banana and their wild relatives (Musaspp.) reveals differences in chromosome structure

Edible banana cultivars are diploid, triploid or tetraploid hybrids which originated by natural cross hybridization between subspecies of diploid Musa acuminata , or between M. acuminata and diploid M. balbisiana . Participation of two other wild diploid species M. schizocarpa and M. textilis was also indicated by molecular studies. Fusion of gametes with structurally different chromosome sets may give rise to progenies with structural chromosome heterozygosity and reduced fertility due to aberrant chromosome pairing and unbalanced chromosome segregation. Only a few translocations have been classified on the genomic level so far and a comprehensive molecular cytogenetic characterization of cultivars and species of the family Musaceae is still lacking. FISH with chromosome-arm specific oligo painting probes was used for comparative karyotype analysis in a set of wild Musa species and edible banana clones. The results revealed large differences in chromosome structure discriminating individual accessions. These results permitted identification of putative progenitors of cultivated clones and clarified genomic constitution and evolution of aneuploid banana clones, which seem to be common among the polyploid banana accessions. New insights into the chromosome organization and structural chromosome changes will be a valuable asset in breeding programs, particularly in selection of appropriate parents for cross hybridization. Highlight Oligo painting FISH revealed chromosomal translocations in subspecies of Musa acuminata (A genome), their intra-specific hybrids as well as in M. balbisiana (B genome) and in interspecific hybrid clones originating from cross hybridization between M. acuminata and M. balbisiana