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Retrotransposon families in rice
H Hirochika1, A Fukuchi, F Kikuchi
1Department of Molecular Biology, National Institute of Agrobiological Resources, Ibaraki, Japan.
Molecular & General Genetics : MGG
|May 1, 1992
Summary
Researchers identified novel retrotransposons in rice using a conserved sequence method. These mobile genetic elements, including Tos1-5, are widespread in rice but absent in other plants, indicating potential activity and a major role in the rice genome.
Area of Science:
- Plant genetics
- Molecular biology
- Genomics
Background:
- Retrotransposons are mobile genetic elements comprising a significant portion of eukaryotic genomes.
- Understanding retrotransposon families in crops like rice is crucial for genome stability and evolution.
Purpose of the Study:
- To isolate and characterize novel retrotransposon families in rice.
- To investigate the distribution and potential activity of these elements in rice and related species.
Main Methods:
- Isolation of retrotransposons using primer binding site sequence conservation.
- Detailed characterization of Tos3-1 structure (LTRs, primer binding site, polypurine tract).
- Southern blotting to detect homologous sequences in various plant species.
- Polymerase chain reaction (PCR) to screen for copia-like elements.
Main Results:
- Three retrotransposon families (Tos1, Tos2, Tos3) were identified in rice.
- Tos3-1 exhibits typical retrotransposon structural features and generates target duplications.
- Homologous sequences for Tos1-3 are present in wild and cultivated rice but not in maize or tobacco.
- Copy number and genomic location of these elements vary, suggesting ongoing activity.
- Two copia-like elements (Tos4, Tos5) were also detected.
- An estimated 1000 retrotransposon copies exist in the rice genome.
Conclusions:
- A novel method for retrotransposon isolation is applicable to other plant species.
- Retrotransposons are a major transposon class in the rice genome, similar to Drosophila.
- The identified retrotransposons show species-specific distribution and potential for activity in rice.