Genomics, banana breeding and superdomestication

Bananas are important for food security, and even under poor conditions give a useful crop. Targets for banana breeding can be divided into five different groups: productivity characters, abiotic stress resistance, biotic stress resistance, post-harvest characters and those related to markets. Yield is a key characteristic selected by breeders and used by farmers, while biotic and abiotic stresses cause major yield losses and unstable production from year to year. Musa genomics has developed rapidly since 2000, with the Global Musa Genomics Consortium coordinating research on the genomics of banana, aiming to assure the sustainability of banana as a staple food crop by an integrated genetic and genomic understanding. In the 21st century, crop improvement has accelerated by the use of genetic maps and DNA markers to identify useful genes, combine desirable traits or resistance genes and accelerate selection, but the difficulty of working with the sterile, triploid banana crop means these approaches have not been used as extensively as in other crops. Now, knowledge of genomics and understanding of crop design allows superdomestication, involving interactions of breeders and genomic scientists to design the characteristics required from a banana cultivar and consider how to produce this ideal cultivar – how to find and evaluate the genes responsible for particular traits, and how to bring them together in a new cultivar. Superdomestication allows definition of a cultivar with a suite of ideal characters ranging from biotic and abiotic stress resistance, through yield, to post-harvest and nutritional quality – many being quantitative trait loci with changing patterns of expression depending on conditions. Collections of germplasm underpin the search for desirable traits, requiring measuring, finding and conserving biodiversity. The combination of expertise with exploitation of the genepool and use of genomic sciences opens a new range of opportunities for the future, requiring further development of Musa genomics.