Perda rápida de DNA como equilíbrio à expansão do genoma através da proliferação de retrotransposon em plantas

Rapid DNA loss as a counterbalance to genome expansion through retrotransposon proliferation in plants

Jennifer S. Hawkins a,1, Stephen R. Proulx b, Ryan A. Rapp a and Jonathan F. Wendel a

+ Author Affiliations

aDepartment of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011; and

bDepartment of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106

Edited by Jeffrey L. Bennetzen, University of Georgia, Athens, GA, and approved August 18, 2009 (received for review April 21, 2009)

Abstract

Transposable elements, particularly LTR-retrotransposons, comprise the primary vehicle for genome size expansion in plants, while DNA removal through illegitimate recombination and intrastrand homologous recombination serve as the most important counteracting forces to plant genomic obesity. Despite extensive research, the relative impact of these opposing forces and hence the directionality of genome size change remains unknown. In Gossypium (cotton), the 3-fold genome size variation among diploids is due largely to copy number variation of the gypsy-like retrotransposon Gorge3. Here we combine comparative sequence analysis with a modeling approach to study the directionality of genome size change in Gossypium. We demonstrate that the rate of DNA removal in the smaller genomes is sufficient to reverse genome expansion through Gorge3 proliferation. These data indicate that rates of DNA loss can be highly variable even within a single plant genus, and that the known mechanisms of DNA loss can indeed reverse the march toward genomic obesity.

C-value cotton genome evolution Gossypium transposable elements

Footnotes

1To whom correspondence should be sent at the present address: Department of Genetics, University of Georgia, Athens, GA 30602. E-mail: jhawkins@uga.edu

Author contributions: J.S.H., S.R.P., R.A.R., and J.F.W. designed research; J.S.H., S.R.P., and R.A.R. performed research; J.S.H., S.R.P., and R.A.R. analyzed data; and J.S.H. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

+++++

PDF gratuito do artigo aqui.