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Published on: February 20, 2012
Evolution of interspersed repetitive elements inGossypium (Malvaceae).
R Hanson1, X P Zhao, M N Islam-Faridi
1Department of Soil and Crop Sciences, TexasA&M University, College Station, Texas 77843-2474;
American Journal of Botany
|June 21, 2011
Summary
Repetitive elements in polyploid cotton (Gossypium hirsutum) largely evolved through intergenomic concerted evolution after polyploidization. This involved A-subgenome elements colonizing or replacing those in the D-subgenome.
Area of Science:
- Genomics
- Evolutionary Biology
- Plant Science
Background:
- Polyploid organisms exhibit complex genomic dynamics.
- The evolution of repetitive elements in polyploids remains poorly understood.
- Cotton (Gossypium hirsutum) is an important AD-genome tetraploid model.
Purpose of the Study:
- To investigate the evolution of interspersed repetitive elements in the polyploid cotton genome.
- To determine the contribution of diploid ancestors to the repetitive element content of the tetraploid.
- To understand the mechanisms driving repetitive element evolution post-polyploidization.
Main Methods:
- Fluorescence in situ hybridization (FISH) was used to map 20 interspersed repetitive elements.
- Probes were hybridized to metaphase chromosomes of Gossypium hirsutum and its diploid ancestors (G. arboreum and G. raimondii).
- Signal distribution was analyzed to infer element origins and evolutionary dynamics.
Main Results:
- Seventeen of 20 repetitive elements hybridized to both subgenomes of Gossypium hirsutum.
- Three elements were specific to the A-subgenome in Gossypium hirsutum.
- Elements showed similar distribution in G. arboreum (A-genome) as in the G. hirsutum A-subgenome, but no signals were detected in G. raimondii (D-genome).
Conclusions:
- The majority of interspersed repetitive elements in Gossypium hirsutum have undergone intergenomic concerted evolution.
- This evolution likely involved A-subgenome elements colonizing the D-subgenome or replacing D-subgenome elements.
- Repetitive element dynamics following polyploidization are crucial for genome evolution in cotton.
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