What is polyploidy?
Here poly means many and ploidy means total number of sets of chromosomes. When a cell contain more than two set of chromosomes i.e. nucleus contain more than its normal complement of chromosome is called a polyploidy.
The specific number of chromosomes is a character of each species is called genome. When plant species contain three or more genomes are termed Polyploidy. Polyploidy can occurs in multiple series of 3,4,5,6,7 etc.
When a cell contain 3 set of chromosomes called triploid, 4 set of chromosomes called tetraploid and so on.
The basic set of chromosomes undergoes multiplications. For example, in Chrysanthemum basic set is x = 9. Its species and hybrids show multiple of 9, such as 18, 27, 36, 45. On the other hand in Nicotiana and Solanum basic set is x = 12 and multiple of somatic chromosome numbers are 24, 48 and 72 and in Triticum it is x = 7 and multiples are 14, 21, 42.
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