Responses of the Cotton Genome to Polyploidy
Cotton has been developed as a particularly useful model system for examining the responses of the genome to polyploidy. Recent studies have provided novel insights and perspectives on genome-wide consequences of polyploidy, as well as the responses of individual genes and effects on gene expression. Comparative BAC sequencing has revealed evidence of genome downsizing in G. hirsutum. Expression studies have shown extensive organ-specific gene silencing and expression changes upon allopolyploidy that continue over evolutionary time. Expression patterns can be partitioned between homoeologous genes such that only one copy is expressed in some organs and only the other copy is expressed in other organs. Abiotic stress can have major effects on the expression of homoeologous genes. Larger scale approaches are starting to be employed that discriminate expression of thousands of homoeologs in a single experiment. An improved understanding of the genomic responses to polyploidy will likely have implications and applications for cotton crop improvement.
KeywordsAbiotic Stress Condition Cotton Genome Homoeologous Gene Allopolyploid Species Expression Bias
We thank a reviewer for helpful comments on the manuscript. Research on cotton genome and gene expression evolution in the Wendel lab has been funded by the NSF Plant Genome and the USDA NRI programs, whose support we gratefully acknowledge.
- Adams K.L. (2008) Insights into the evolution of deplicated gene expression in polyploids from Gossypium. Botany 86, 827–834.Google Scholar
- Bennett, M.D. and Leitch, I.J. (2005) Genome size evolution in plants. In: T. R. Gregory (Ed.) The evolution of the genome. Elsevier, San Diego, pp. 89–162.Google Scholar
- Flagel L., Udall J., Nettleton D., Wendel J.F. (2008) Duplicate gene expression in allopolyploid Gossypium reveals two temporally distinct phases of expression evolution. BMC Biol. 6(16).Google Scholar
- Liu, B., Vega, J. M., and Feldman, M. (1998a). Rapid genomic changes in newly synthesized amphiploids of Triticum and Aegilops. II. Changes in low-copy coding DNA sequences. Genome 41, 535–542.Google Scholar
- Liu, B., Vega, J. M., Segal, G., Abbo, S., Rodova, M., and Feldman, M. (1998b). Rapid genomic changes in newly synthesized amphiploids of Triticum and Aegilops. I. Changes in low-copy non-coding DNA sequences. Genome 41, 272–277.Google Scholar
- Liu, Z. and Adams, K. L. (2007) Expression partitioning of genes duplicated by polyploidy in response to abiotic stress and during organ development. Curr. Biol., in press.Google Scholar