Polyploidy Breeding as a Tool for Improvement of Flower and Ornamental Crops

Abstract Polyploidy has played a significant role in the evolution and diversification of higher plants. Polyploidy may have resulted naturally by the formation of unreduced gametes or can also be artificially developed by doubling the chromosome number in somatic cells. Artificial polyploidization can be achieved with antimitotic chemicals, i.e. colchicine, oryzalin, etc. This method can be done under in vivo or in vitro conditions. Ploidy changes lead to modifications in nuclear DNA content, gene expression and all other developmental processes, which result in morphological, anatomical and physiological changes in polyploid plants. Polyploid plants show increased organ size and biomass production together with enhanced yield and improved ability to withstand both biotic and abiotic stresses and yield increased production of primary and secondary metabolites. In ornamental plants, this enables the production of larger flowers and in turn higher aesthetic and economic significance. Polyploid plants could serve as superior parent material for hybridization programs, can help to restore fertility because of doubling of chromosomes, thus leading to new varieties which can help breeders to develop improved hybrids and novel types with improved fertility and other advantageous traits. In this review, the importance of polyploidy and its types, methods of polyploidy induction, the roles of antimitotic agents as well as effects of polyploidization on morphological, physiological and quality parameters, along with its impact on biotic and abiotic stress and the production of secondary metabolites with respect to flower and ornamental plants are discussed.