Understanding mechanisms of novel gene expression in polyploids

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Trends in genetics




Polyploidy has long been recognized as a prominent force shaping the evolution of eukaryotes, especially flowering plants. New phenotypes often arise with polyploid formation and can contribute to the success of polyploids in nature or their selection for use in agriculture. Although the causes of novel variation in polyploids are not well understood, they could involve changes in gene expression through increased variation in dosage-regulated gene expression, altered regulatory interactions, and rapid genetic and epigenetic changes. New research approaches are being used to study these mechanisms and the results should provide a more complete understanding of polyploidy.

The increase in chromosome number and consequent genome redundancy created by polyploidy has long been recognized as a prominent feature in the evolution of flowering plants [1] and some animal species [2]. Many of our most important crop plants have the hallmarks of autopolyploidy (e.g. alfalfa and potato) or allopolyploidy (e.g. wheat, oat, cotton, coffee and canola) (Box 1). Other crops, such as maize [3], soybean [4] and cabbage [5], appear to have undergone polyploidization in their ancestry (paleopolyploids), although the evidence for this has been obscured by genomic rearrangements. Even the small genome of the model organism Arabidopsis thaliana appears to have undergone polyploidy in its history based on analysis of the full genome sequence [6]. Perhaps every plant species has gone through cycles of polyploidy during their evolution, although we can only recognize the most recent events [7].