polyploidaatioon

Polyploidaatioon, often referred to as polyploidization or whole genome duplication (WGD), is a biological process where an organism acquires one or more complete sets of chromosomes. In sexually reproducing organisms, this typically results in cells containing more than two sets of homologous chromosomes, a condition known as polyploidy. Normal diploid organisms have two sets of chromosomes, one inherited from each parent. Polyploid organisms can be triploid (three sets), tetraploid (four sets), or even have higher ploidy levels.

This phenomenon can occur through various mechanisms. In plants, it frequently arises from errors during meiosis, the cell division process that produces gametes. If the chromosomes fail to separate properly, a diploid gamete can be formed. Fertilization of a diploid gamete by a normal haploid gamete leads to a triploid zygote, while the fusion of two diploid gametes results in a tetraploid zygote. Polyploidization can also occur somatically, affecting only certain tissues or organs.

Polyploidization has played a significant role in the evolution of many plant species, contributing to increased genetic diversity and novel traits. It is often associated with larger cell size, increased vigor, and altered morphology. In agriculture, polyploidy is exploited to produce crops with desirable characteristics, such as larger fruits or increased disease resistance. While less common in animals, polyploidy does occur in some species, including certain fish, amphibians, and invertebrates.