Tetraploid
/ˈtɛtrəˌplɔɪd/
Definition
Tetraploid describes a plant or cell with four complete sets of chromosomes, written as 4n, instead of the usual two sets found in diploids. It is a biological chromosome condition, or ploidy level. In plants, tetraploid forms can arise naturally or through breeding and often differ from diploid relatives in traits such as cell size, fertility, and the way they combine genetically with other plants.
Botanical Significance
- Meiosis and fertility: In a tetraploid plant, chromosome pairing during meiosis can be more complex than in a diploid plant. Fertility may stay normal in some species, but irregular pairing can reduce seed set in others.
- Visible plant traits: Extra chromosome sets are often linked with larger cells, which can contribute to thicker leaves, bigger flowers, pollen, or fruit, and a heavier overall texture. The effect varies by species and breeding line.
- Plant breeding value: Breeders use tetraploid lines to create new cultivars and to cross plants with different chromosome levels. This can help produce seedless triploid crops, as seen in some watermelon breeding programs.
- Speciation and classification: Whole-genome duplication has played a major part in plant evolution, and tetraploid forms can become distinct populations or species. For botanists, chromosome number can therefore matter in identification and classification.
Related Terms
Triploid
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Genotype
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Hybrid
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Hybridization
Hybridization is the crossing of two genetically distinct plants, usually within the same species or between closely…
Species
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