Impact of retroelements in shaping the Petunia genome

Abstract

Retroelements, defined by their dependence on reverse transcription for replication, are found in the genomes of bacteria, fungi, animals and plants. This chapter summarizes current knowledge about the structure, function and evolution of representatives from two retroelement groups identified in Petunia. The presence of both a viral retroelement - an inducible endogenous plant pararetrovirus, EPRV- and non-viral retroelements in the form of LTR-retrotransposons makes Petunia an ideal model system to study possible retroelement interactions. Phylogenetic relationships have been determined and chromosomal co-localization of EPRV and Metaviridae, one group of LTR-retrotransposons, has been demonstrated. The impact of partly overlapping replication pathways on element interference is discussed. While studies in Petunia and related species have led to tremendous progress in our understanding of these elements we are just beginning to comprehend the consequences of their presence and activities in their hosts.