Emerging trends in polyploidy research

Abstract

The Key Word ‘Polyploidy’ (i.e., the presence of more than two chromosome sets/more than two complete genomes in a cell) coined by Winkler in 1916 [25] has lived nearly a Century. Genome sizes in plants are remarkably diverse, with a 2350-fold range from the smallest 63 Mb (in two species of carnivorous Genlisea, G. aurea (2n=approximately 52) and G. margaretae (2n=approximately 40)), to the largest 149 000 MB (in Paris japonica, 2n=8x=40), divided into n=2 to n=aprox. 600 chromosomes [1]. The polyploidy phenomenon has intrigued biologists over the years and many attractive hypotheses have been proposed in an attempt to assign functionality to the increased content of a duplicated genome [14, 19–21].With the advent of newer tools of genetic analysis there has been tremendous resurgence of interest in polyploidy research, and several publishers have brought out special issues of the journals / reference books [4, 6, 12, 17, 18, 22, 24]. Ch romosome doub l i n g i s b r ough t abou t by endoreduplication/2n gametes/inter-genomic hybridization— all constraining genetic stability. That polyploidy can be induced with chemicals such as Colchicine, was first demonstrated by OJ Eigsti in 1935 cited in Blakeslee and Avery [2]. Genome duplication impedes sexual reproduction and may impact growth and development. A change to tetraploid state nearly doubles the cell volume and enhances cell surface area by about 1.5 times, often facilitating development of larger organs in plants. But in animals there is a tendency to preserve the same body size by reducing the overall number of cells, thus indicating differential effect to polyploidy change across the taxonomic groups [13].