Repetitive DNA in Plant Genomes

Repetitive DNA sequences, both tandemly repeated satellite sequences and dispersed transposable elements are major components of all eukaryotic genomes. Whole genome sequencing projects attempt to mask repeats deliberately to allow assembly and tandem repeats are difficult to find while many dispersed elements are present in large abundance and can be analysed by specific repeat finding algorithms. I will discuss the composition of transposable elements in Petunia, Taraxacum and other genomes using in silico DNA analysis and fluorescent in situ hybridization experiments. Within Solanaceae it is interesting to note that genome expansion that is due to increase in repetitive DNA sequences is by amplification of different elements in different species. In Petunia large numbers of DNA transposons are found which in turn is reflected in the relatively low number of LTR retro-elements. The Petunia genome, also harbours endogenous pararetroviruses including the Petunia vein clearing virus (PVCV) that in the hybrid Petunia, P. hybrida, is linked to disease outbreaks. In the parental genomes P. axillaris and P. inflata much lower amounts of PVCV were found as single copies or in arrays of several degenerate copies. In the genus Taraxacum with mainly apomictic species and uncertain phylogenetic relationships and taxonomy, we speculate that the variation seen between species, subspecies and populations is caused by transposable elements.

Co-authors: Rubar H.M. Salih and Pat Heslop-Harrison (University of Leicester) and Katja Richert-Poeggeler (Federal Research Centre for Cultivated Plants, Braunschweig, Germany)

Support is acknowledged from Kurdistan Regional Government and EU FrameworkV programme Paradigm. For references see http:\\www.molcyt.com