Abstract:
Of the plant genomes, the mobile genetic elements (MGEs) or transposable elements (TEs) are most copious elements, which have contributed to genome size duplication, evolution, diversification, plasticity, and explained the size variations in them. DNA transposons are utilized as best genetic tools to inert a piece of foreign DNA into a genome and are successfully used for transgenesis and insertional mutagenesis in different plants. They are useful tools to analyse the embryonic development, regulatory genome, study embryonic development, identify genes and pathways implicated in disease or pathogenesis of pathogens, and even contribute to gene therapy. The current work focused on the genome organization of diversified MGEs in various plants by exploiting the bioinformatics, molecular and cytogenetic techniques. In the plant genomes, the LTR retrotransposons upper families like Copia, Gypsy, DIRsand retroviruses (caulimoviruses and pararetroviruses) were actively and abundantly proliferating. The Copia and Gypsy superfamilies enriched genome by having the high copy numbers followed by retroviruses (caulimoviruses and pararetroviruses) and DIRS elements in various fungal (Fusarium, Tricholoma, Colletotrichum, Aspergillus, Saccharomyces), gymnosperms (Cycas, Cedrous, Pinus,) and angiosperms (Triticum, Zea mays, Oryza, Hordeum, Arabidopsis, Arachis, Brassica, Beta, Manihot, Musa, Citrus, Dianthus, Fragaria, Glycine, Lilium, Lycopersicon, Pisum, Petunia, Mirabilis, Nicotiana, Sorghum, Saccharum etc.). The Non-LTR retrotransposons were represented by various superfamilies of LINEs and SINEs, while DNA transposons were abundantly represented by CACTA, hAT, Harbinger, Mariner, Mutator and MITEs superfamilies, while Helitron, Politron and Maverik were rarely identified. PCR amplification of reverse transcriptase (RT) of Retrotransposons and transposase (TNP) of DNA transposons revealed their distribution among various genomes, with some elements were found to be specie or genera specific, while others were mobilized by horizontal transfer. The evolutionary relationship of these elements resolved them into superfamily and family specific lineages.