Isolation and characterization of Ty1-copia group of LTRs in genome of three species of Datura: D. innoxia, D. stramonium and D. metel.

Retrotransposons (RT) constitute a major fraction of plant genome. They are implicated in evolution and sequence organization. These elements have been proposed to have major role in evolution and variation in genome size. The sequence information of these RT regions in terms of divergence and conservation could be utilized for determining the interrelationship among various copia retrotransposons within the genome. In order to assess the diversity of Ty1-copia group of retroelements, reverse transcriptase (RT) sequence was amplified from genomes of three medicinally important Datura species: D. innoxia, D. stramonium and D. metel using the primers derived from two conserved domains of RT region. A total of twenty one independent amplicons from RT regions were cloned, sequenced and compared. The intra-family divergence at amino acid level ranged from 4 to 52 %. Though intra-family RT sequences are conserved, no two sequences are identical. Southern blot hybridization suggested that Ty1-copia-like retrotransposons are dispersed throughout the Datura genome. The results indicate a high degree of heterogeneity among the Ty1-copia group of retroelements in Datura species.