Sequence composition, organization, and evolution of the core Triticeae genome

Area of Science:

• Plant genomics
• Molecular evolution
• Wheat genetics

Background:

• The Triticeae tribe, including wheat, has a large genome.
• Understanding genome expansion is key to crop improvement.
• Aegilops tauschii is the D-genome donor of bread wheat.

Purpose of the Study:

• Investigate genome composition and expansion in the Triticeae core genome.
• Analyze the role of transposable elements (TEs) in genome size.
• Evaluate methylation filtration for gene-rich region isolation.

Main Methods:

• Sequencing of unfiltered genomic shotgun (trs) and methylation-filtration (tmf) libraries of A. tauschii.
• Analysis of wheat expressed sequence tags (ESTs).
• Quantification of repetitive elements, genes, and low-copy sequences.

Main Results:

• A. tauschii D-genome is 91.6% repetitive elements, with TEs comprising 68.2%.
• TEs are unevenly methylated, mostly transcribed, and contribute to genome expansion.
• TE copy number increased post-polyploidization; nested insertions and recombination were extensive.

Conclusions:

• Transposable elements significantly drive genome expansion in the Triticeae core genome.
• Methylation filtration can aid in isolating gene-rich regions, though less efficient than in maize.
• Understanding TE dynamics is crucial for wheat genome evolution and breeding.