37 These results are in line with reports that cells without complete DNA repair can result in mitotic arrest, errors in chromosome segregation, and formation of aberrant polyploidy cells, subsequently leading to cell death.
For each gene that was studied, allopolyploid species should have two homelogs, representing descendants from the A-genome and D-genome donors at the time of polyploidy formation.
In theory, there are two homologs in tetraploid cotton species, representing descendants from the A-genome and D-genome donors at the time of polyploidy formation.
Interestingly, studies in plants have shown that the rate of polyploidy formation varies with environmental conditions and parental origin [ 12, 13].
Abnormal mitotic spindle formation prior to the development of polyploidy was confirmed in the present study by confocal microscopy.
Furthermore, expression of N-terminal modified Hec1 in cancer cells can be used to specifically induce chromosome segregation within multipolar spindles and trigger the formation of extremely aneuploid and/or polyploidy daughter cells that will be effectively eliminated from the growing population (Totta and Degrassi, unpublished).
However, there is little evidence for any rapid methylation changes in polyploidy formation of cotton and ploidy watermelon (Liu et al. 2001; Wang et al. 2009).
Interestingly, the observation that duplicated apple genes related to photosynthesis and carbohydrate metabolism, may have been preferentially retained during the polyploidy formation of the apple genome suggests a parallelism with these findings.
The process of polyploidy evolution leading to stabilization and species formation have been studied and confirmed by modern molecular genetic techniques [ 3, 8- 11].
A disadvantageous effect of polyploidy is the possible disturbance of meiosis by doubled chromosomes which may prevent correct bivalent formation [ 7].
