Breeding of fragrant cyclamen by interspecific hybridization and ion-beam irradiation

Conventional breeding of cyclamen has relied on crossings among Cyclamen persicum cultivars without consideration of the scent of the flowers. Cyclamen purpurascens is a wild species with the most fragrant flowers in the genus Cyclamen. Allodiploid (2n = 2x = 41, AB) and allotriploid (2n = 3x = 65, AAB) plants have been produced from crosses of diploid and autotetraploid cultivars of C. persicum (2n = 2x = 48, AA; 4x = 96, AAAA) × diploid wild C. purpurascens (2n = 2x = 34, BB) by embryo rescue, but are sterile. Fertile allotetraploid (2n = 4x = 82, AABB) plants have been produced by chromosome doubling of the sterile allodiploids in vitro. Autotetraploid C. purpurascens (2n = 4x = 68, BBBB) has been produced by chromosome doubling of diploid C. purpurascens, and other fertile allotetraploids (2n = 4x = 82, AABB) have been produced from crosses of autotetraploid cultivars of C. persicum × autotetraploid C. purpurascens by embryo rescue. Commercial cultivars of fragrant cyclamen have been bred by conventional crosses among the allotetraploids. Mutation breeding using ion-beam irradiation combined with plant tissue culture has resulted in fragrant cyclamens with novel flower colors and pigments. In contrast, allotriploids (AAB) have not been commercialized because of seed sterility and poor ornamental value. The flower colors are determined by anthocyanins and flavonol glycosides or chalcone glucoside, and the fragrances are determined by monoterpenes, sesquiterpenes, phenylpropanoids, or aliphatics. Techniques for the production of fragrant cyclamen and knowledge of flower pigments and volatiles will allow innovation in conventional cyclamen breeding.