Citrus polyploidy - origins and potential for cultivar improvement

Euploidy in Citrus is represented by monoploids, diploids, triploids, tetraploids, pentaploids and octoploids. Such plants offer considerable potential for cultivar improvement through expliotation of their horticulturally useful characteristics and as parents in breeding programmes. Further, they may also facilitate investigation of Citrus genetics. Their diversity of origins (sexual and apomictic, natural and artificial) allows flexibility in their exploitation. The development of seedless triploid varieties has already proven practical with the release of commercial cultivars, and the potential of somatic tetraploids as dwarfing rootstocks warrants thorough investigation. The advent of modern biotechnology holds promise for the exploitation of monoloids in breeding. This review examines the various origins of Citrus polyploidy and considers the potential for exploitation of certain polyploids.