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Grass genomes
J L Bennetzen1, P SanMiguel, M Chen
1Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA.
Summary
Maize genomes contain over 50% repetitive DNA, mainly retrotransposons between genes. Rice and sorghum genomes have fewer retroelements, with genes often located adjacently, unlike maize.
Area of Science:
- Genomics
- Comparative genomics
- Plant molecular biology
Background:
- Previous grass genome studies focused on genetic maps or single genes.
- Large-scale genome structure and intergenic regions were less explored.
Purpose of the Study:
- Investigate large contiguous genome segments in maize, sorghum, and rice.
- Characterize intergenic spaces and repetitive DNA content.
- Compare genome organization and collinearity across these grass species.
Main Methods:
- Analysis of large contiguous genomic segments.
- Focus on intergenic DNA.
- Comparative analysis of maize, rice, and sorghum genomes.
Main Results:
- Maize genome is >50% interspersed repetitive DNA (retrotransposons), less abundant in rice and sorghum.
- Maize genes are often flanked by retrotransposon blocks, while rice and sorghum genes are frequently adjacent.
- Genes show conserved locations and orientations across species, but rearrangements (exceptions to collinearity) are common.
Conclusions:
- Grass genome structure knowledge aids gene discovery.
- General rules and biological significance of grass genome organization require further study.
- The nature and frequency of exceptions to genome structure and collinearity patterns are largely unknown.