Insights into the evolution of duplicate gene expression in polyploids from Gossypium

• Published in: Botany Vol. 86; no. 8; pp. 827 - 834
• Main Author: Adams, K.L
• Format: Journal Article
• Language: English
• Published: NRC Research Press 01.08.2008
• Subjects: alleles; allopolyploidy; duplicated gene expression; evolution; gene expression; gene silencing; Genetic aspects; genome; Gossypium; hexaploidy; interspecific hybridization; literature reviews; phenotype; plant stress; plant tissues; Polyploidy; speciation; United States
• ISSN: 1916-2804; 1916-2790; 1916-2804
• DOI: 10.1139/B08-042

Polyploidy is a prominent mechanism of speciation in plants that can lead to novel phenotypes. Polyploidy is characterized by novel genetic and genomic consequences that provide raw material for morphological evolution. Polyploids often exhibit changes in genome organization and gene expression compared with their diploid progenitors. The five allopolyploid cotton (Gossypium) species and newly created cotton neopolyploids have been developed as a useful group for studies of duplicated gene expression in polyploids. Here I review recent studies on the evolution of duplicate gene expression in polyploid cotton. In addition I present new expression data from cotton neopolyploids that address the effects on expression of adding a third genome in an allohexaploid, and that provide insights into fine scale organ- specific silencing. Substantial changes in gene expression have occurred in homoeologous genes (gene pairs duplicated by polyploidy), including organ-specific gene silencing and subfunctionalization. Many of the changes in gene expression have occurred on an evolutionary timescale, whereas others occur immediately after genome merger and within a few generations. Abiotic stress can affect the expression of homoeologous gene expression, causing expression partitioning between homoeologs. To examine the effects of interspecific hybridization, without chromosome doubling, on gene expression, interspecific hybrids have been studied. Extensive variation in allelic expression was observed upon hybridization that varied by gene, organ, and genotype. Several hypotheses have been proposed for why gene expression is altered in allopolyploids and interspecific hybrids.