• gymnosperms
• LINEs
• transposable elements

Transposable elements (TEs) are a major component of plant genomes heavily contributing to their structure and functioning. They are powerful mutagenic agents, they are the principal responsible of genome size variation even between closely related species, they contribute to transcription regulation and they originate chromosomic rearrangements. Furthermore, TEs have a primary role in the evolution of species and the mobilization of these elements can modify gene regulatory network.
Gymnosperms have large genomes of which only a small fraction encodes for genes. The majority of the non-coding DNA is composed by TEs, in particular retroelements. There are a lot of studies focusing on LTR retrotransposons, whereas the other important class of retroelements (i.e.LINEs:Long Interspersed Nuclear Elements) was scarcely studied so far. Because of this reasons I decided to focus my attention on LINEs.
Similarity searches based on dot-plot analisys allowed the identification of about 200 LINEs for each species studied and the arrangement of these elements in families.
As a result, 7 families of LINEs are identified in Ginkgo biloba, 5 families in Pinus taeda and 6 families in Picea abies. For each family, the structure of a representative LINE was analized and characterised using the software ORF-Finder.
RepeatMasker has been used to quantify the presence of the identified LINEs in each genome: in Ginkgo biloba the percentage is 1,69%, in Pinus taeda is 1,2% and in Picea abies is 1,76%.
Further analisys in phylogeny are done with MEGA6 to better understand how LINEs are related in the three species considered.