Autopolyploide

Autopolyploide, or autopolyploid, is an organism that has more than two complete sets of chromosomes, all derived from a single species. This contrasts with allopolyploidy, where chromosome sets come from different species. Autopolyploids arise when genome duplication occurs within a species, either through the formation of unreduced (2n) gametes that fuse (2n + 2n = 4n, for example) or by somatic chromosome doubling in a cell, or through genome duplication early in development.

The additional chromosome sets are typically homologous, which affects how chromosomes pair and segregate during meiosis. Autopolyploid meiosis often involves multivalent chromosome pairing (for example, quadrivalents in tetraploids), leading to complex and sometimes irregular inheritance. In time, some autopolyploids show diploidized inheritance with more regular, disomic segregation as pairing becomes more restricted to homologous chromosomes.

Autopolyploids commonly exhibit increased cell and organ size, sometimes translating into larger overall plant size and altered physiology. They may also display improved vigor or stress tolerance, but fertility can be reduced if meiotic pairing is irregular and results in unbalanced gametes. Because their chromosome number is often distinct from the parent, autopolyploids can become reproductively isolated, contributing to speciation.

In agriculture and horticulture, autopolyploidy is used to create seedless fruit, sterile varieties, or plants with desirable traits. A classic example is the autotetraploid potato (Solanum tuberosum). Autopolyploidy is more common in plants than in animals, where meiotic complications and fertility issues frequently limit establishment. See also polyploidy, autopolyploidy mechanisms.