From The Polyploidy Portal

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Why is polyploidy important?

Polyploidy has long been recognized as a prominent force shaping the evolution of plants (Winge 1917; Karpchenko 1927; Stebbins, 1950; 1971), especially ferns (Wagner and Wagner, 1980; Werth et al., 1985, Vogel et al., 1999) and flowering plants (Soltis and Soltis, 2000; Wendel, 2000). Many important crop plants, such as alfalfa, cotton, potato, and wheat, are obvious polyploids while others, such as maize, soybean, and cabbage, retain the vestiges of ancient polyploid events (paleopolyploids). Based on fossil records, 70% of angiosperms were estimated to have had a polyploidization event in their species’ history (Masterson 1994). More recent evidence based on genome analyses suggest that many more organisms have polyploid origins, including those with small genomes such as Arabidopsis and yeast (AGI, 2000; Blanc et al., 2003; Langkjaer et al., 2003).

An example of an allopolyploid that shows hybrid vigor over its diploid progenitors is resynthesized Brassica napus.

Although polyploidy is now widely recognized as a frequent event in evolution, we don't fully understand why polyploids have been so successful. Many polyploids are more vigorous than their diploid progenitors and both auto- and allo-polyploids have built in mechanisms for mantaining high levels of heterozygosity. These polyploids may exhibit a phenomenon similar to hybrid vigor, or heterosis. Polyploids also are known to exhibit new phenotype variation that can arise with aor shortly after polyploid formation. Our research group is studying the alteration in genome structure and genome expression that could lead to these new, potentially advantageous, phenotypes. Hybrid vigor, also known as heterosis, is an agriculturally important phenomenon describing the observation that the hybrid offspring of two inbred genetically different varieties produces higher yields than either one of the two parental lines.

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