autotetraploidne

Autotetraploidy, or autotetraploidy, is a form of polyploidy in which an organism possesses four complete sets of chromosomes (4n), all derived from a single species. It is a type of autopolyploidy, in contrast to allopolyploidy, where the chromosome sets come from different species. Autotetraploids arise when a diploid genome is doubled (doubling of 2n to 4n) or when unreduced gametes (2n) fuse from the same species, a process that can be induced artificially in plants using antimitotic agents such as colchicine or oryzalin.

Meiosis in autotetraploids presents challenges because there are four homologous chromosomes to pair. Multivalent formations, such as tetravalents, can lead to irregular segregation and reduced fertility. Some autotetraploids maintain fertility through pairing patterns that favor more regular assortment or through postmeiotic chromosome doubling in gametes. In general, autotetraploids exhibit larger cells and may show altered vigor, morphology, and phenotypic traits compared with their diploid progenitors. Their inheritance patterns can be tetrasomic, meaning any of the four homologous chromosomes can pair and segregate, which affects genetic behavior and breeding.

Natural occurrence and agricultural relevance: Autotetraploidy occurs in several plant groups and is important in plant evolution and speciation, providing immediate reproductive isolation from diploid relatives. Many crops incorporate autotetraploid or segmental tetraploid genomes; for example, cultivated potato (Solanum tuberosum) is a well-known autopolyploid tetraploid, and alfalfa (Medicago sativa) is also tetraploid. Autotetraploidy can be exploited in breeding to stabilize desirable traits, increase heterozygosity, and modify plant size and metabolism, but it can also introduce fertility and breeding complexities due to altered meiosis.