Abstract
Polyploidy occurs naturally in plants through cell division errors or can artificially be induced by antimitotic agents and has ecological effects on species adaptation, evolution, and development. In agriculture, polyploidy provides economically improved cultivars. Furthermore, the artificial induction of polyploids increases the frequency; thus, it accelerates obtaining polyploid plants used in breeding programs. This is the reason for its use in developing many crops of economic interest, as is the case of orchids in the flower market. Polyploidy in ornamental plants is mainly associated with flowers of larger size, fragrance, and more intense coloring when compared to naturally diploid plants. Currently, orchids represent the largest flower market worldwide; thus, breeding programs aim to obtain flowers with the larger size, durability, intense colors, and resistance to pathogens. Furthermore, orchid hybridization with polyploidy induction has been used to produce improved hybrid cultivars. Thus, the objective of this review was to compile information regarding the natural occurrence, importance, and methods of induction of polyploidy in orchids. The study also summarizes the significance of polyploids and techniques associated with artificially inducing polyploidy in different orchids of commercial relevance.
Highlights
Polyploidy is defined as the increase in chromosome number, generating organisms with more than two complete sets of chromosomes
Polyploidy is artificially induced by applying antimitotic agents such as colchicine, oryzalin, trifluralin, propyzamide, and amiprofos-methyl (APM) on tissues, organs, or entire plants [83]
The rates of obtaining polyploid plants ranged from 11.1% to 60%, and colchicine was used as an antimitotic in 89% of the studies and oryzalin in only two studies
Summary
Polyploidy is defined as the increase in chromosome number, generating organisms with more than two complete sets of chromosomes. The occurrence of endopolyploidy levels in plant organs are variable [9], and their frequency may differ due to certain factors like the taxonomic position of the plant, size of the genome, and dissimilarities between individuals of the same family or between varieties or ecotypes of the same species [9,10,11,12] Another interesting aspect of natural polyploidy is the formation of unreduced gametes (2n). The development of unreduced gametes results in polyploidy in plants by the fusion of unreduced gametes or between a reduced and an unreduced gamete, originating polyploid organisms by sexual reproduction This mechanism is mainly responsible for an increase in chromosome number in plants [5,13]
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