title: Copia and Gypsy retrotransposons activity in sunflower (Helianthus annuus L.).
abstract: BACKGROUND
  Retrotransposons are heterogeneous sequences, widespread in eukaryotic genomes, which refer to the so-called mobile DNA. They resemble retroviruses, both in their structure and for their ability to transpose within the host genome, of which they make up a considerable portion. Copia- and Gypsy-like retrotransposons are the two main classes of retroelements shown to be ubiquitous in plant genomes. Ideally, the retrotransposons life cycle results in the synthesis of a messenger RNA and then self-encoded proteins to process retrotransposon mRNA in double stranded extra-chromosomal cDNA copies which may integrate in new chromosomal locations.
  
  
  RESULTS
  The RT-PCR and IRAP protocol were applied to detect the presence of Copia and Gypsy retrotransposon transcripts and of new events of integration in unstressed plants of a sunflower (Helianthus annuus L.) selfed line. Results show that in sunflower retrotransposons transcription occurs in all analyzed organs (embryos, leaves, roots, and flowers). In one out of sixty-four individuals analyzed, retrotransposons transcription resulted in the integration of a new element into the genome.
  
  
  CONCLUSIONS
  These results indicate that the retrotransposon life cycle is firmly controlled at a post transcriptional level. A possible silencing mechanism is discussed.
authors.affiliation: Dipartimento di Biologia delle Piante Agrarie, Università di Pisa, I-56124 Pisa, Italy. m.vukich@kayser.it
authors.forename: Marco
authors.initials: M
authors.lastname: Vukich
authors.forename: Tommaso
authors.initials: T
authors.lastname: Giordani
authors.forename: Lucia
authors.initials: L
authors.lastname: Natali
authors.forename: Andrea
authors.initials: A
authors.lastname: Cavallini
mesh_terms: D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D006368:Helianthus / Q000235:genetics*; D010802:Phylogeny; D018749:RNA, Plant / Q000235:genetics; D018626:Retroelements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D018749:RNA, Plant; D018626:Retroelements