African Journal of Biotechnology Vol. 2 (6), pp. 165–168, June 2003   

ISSN 1684-5315  © 2003 Academic Journals

Isolation, characterization, and phylogenetic analysis of copia-like retrotransposons in the Egyptian cotton Gossypium barbadense and its progenitors

Abdel Ghany A. Abdel Ghany¹ and Essam A. Zaki^2*

¹Institute of Efficient Productivity, Zagazig University, Zagazig

²Genetic Engineering & Biotechnology Research Institute, GEBRI, Research Area, Borg El Arab, Post Code 21934, Alexandria, Egypt.

*Corresponding author; Current Address: Department of Biological Sciences, 1392 Lilly Hall of Life Sciences, West Lafayette, IN 47907-1392, Phone (765) 494-9837 Fax (765) 496-1496, E-mail: ezaki@purdue.edu.  

Accepted 16 may 2003

We have used the polymerase chain reaction to analyze copia-like retrotransposons in the Egyptian cotton and its progenitors. All three cotton species studied contain reverse transcriptase fragments from copia-like retrotransposons. Sequence analysis of these reverse transcriptase fragments reveals that each is different from the others, with predicted amino acid diversities between 9 and 94%. The detection of stop codons and insertions/deletions in the derived amino acid sequences of the Gossypium RT clones, suggests that these clones represent defective retrotransposons. The presence of these sequences in G. barbadense progenitors, however, suggests the presence of active retrotransposons capable of producing new functional copies at an appropriate rate to compensate for the mutational loss of old ones. Phylogenetic analysis provided strong bootstrap support for a monophyletic origin of plant copia-like retrotransposons, yet showed high diversity within all species. Our results suggest that both vertical transmission of copia-like retrotransposons within G. barbadense lineages, and horizontal transmission between G. barbadense and its progenitors have played major roles in the evolution of copia-like retrotransposons in Gossypium.         

Keywords: Genome structure, Gossypium, repetitive DNA, polyploidy, sequence diversity, retrotransposons.

Abbreviations; PCR: polymerase chain reaction, RT: reverse transcriptase gene.