. certain varieties of chrysanthemums contain 18, 36, 54, 72, and 90 chromosomes; all are multiples of a basic set of nine chrom
osomes. how would you describe these varieties genetically? what feature do the karyotypes of each variety share? a variety with 27 chromosomes has been discovered, but it is sterile. why?
The varieties of chrysanthemums containing all multiples of nine chromosomes are autopolyploids. Their karyotypes share the feature of an even number of basic haploid chromosome sets.
Autopolyploids are described as the chromosome sets of an individual when more than two sets of chromosomes are present. They are specifically from the same specie. They can occur when pair of homologous chromosomes have not separated into different nuclei during meiosis. Since, during meiosis, the chromosome sets are separated equally thus karyotypes have an equal number of haploid chromosomes.
Organisms with 27 chromosomes are Triploids(3n) that are sterile because Trivalents at meiosis 1 would form a high number of unbalanced gametes to be formed.
