Untitled

Abstract

The genomic organisation and diversity of the Ty1-copia group retrotransposons has been investigated in several crop plants and their relatives from both dicotyledonous and monocotyledonous families, including potato (Solanum tuberosum), faba beans (Vicia faba), Vicia melanops, Vicia sativa, barley (Hordeum vulgare), rye (Secale cereale), and onion (Allium cepa). Extreme heterogeneity in the sequence of the Ty1-copia retrotransposons from all these plants was revealed following sequence analysis of reverse transcriptase fragments. The estimated copy numbers of the Ty1-copia group retrotransposons for the genomes of S. tuberosum, L. esculentum, A. cepa, S. cereale, and V. faba is highly variable, ranging from a few hundred to approximately a million copies per genome. In situ hybridisation data from metaphase and prophase chromosomes of V. faba, S. cereale, and H. vulgare suggest that retrotransposon sequences are dispersed throughout the euchromatic regions of the genome but are almost undetectable in most heterochromatic regions. In contrast, similar data from metaphase chromosomes of A. cepa suggests that although retrotransposon sequences are dispersed throughout the euchromatic regions of the genome, they are predominantly concentrated in the terminal heterochromatin. These results are discussed in the context of the role played by the Ty1-copia group retrotransposons in the evolution of the plant genome. Lastly, the application of retrotransposon sequences as genetic markers for mapping genomes and for studying genetic biodiversity in plants is presented.

Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV and NBO analysis of 2-chlorobenzonitrile by density functional method

“…The vibrational spectra of benzene derivatives, benzonitriles and substituted benzonitriles were reported by Green and Harrison [3]. Pavan Kumar and Harrison [4] reported the vibrational analysis of substituted benzonitriles. They carried out vibrational spectra, normal coordinate analysis and transferability of force constants of mono halogenated benzonitriles.…”

IRAP: An efficient retrotransposon‐based electrophoretic technique for studying genetic variability among geographical isolates of Schistosoma japonicum

“…The main manifestations they generally show in genome include widespread chromosomal dispersion, variable copy number, and random distribution in the genome [3,4]. The ''copy-and-paste'' mechanism of retrotransposons gives advantages that they could replicate by successive transcription, reverse transcription, and insertion of the new cDNA copies back into the genome elsewhere, fairly like retroviruses [5][6][7].…”

Retrotransposons and their Role in Plant—Genome Evolution

“…Until now the Ty1-copia group is the best-characterized LTR retrotransposon group in plants (18,43,48,76,83,93). In at least some plant species Ty1-copia group retrotransposons are so numerous that they comprise major fractions of the genome (64,65,74).…”