GYPSY-LIKE RETROTRANSPOSONS ARE WIDESPREAD IN THE PLANT KINGDOM

Retrotransposons propagate via an RNA intermediate which is then rever se-transcribed and packaged into viruslike particles. They are either copia-or gypsy like in coding domain order and sequence similarity, th e gypsy-like elements sharing their organization with the retroviruses but lacking retroviral envelope domains. Copia-like retrotransposons, or at least their reverse transcriptase domains, appear broadly distr ibuted in higher plants, but gypsy-like elements have been reported on ly for scattered species. The authors have exploited the difference in domain order between these groups to amplify and clone segments bridg ing the reverse transcriptase - integrase region of specifically gypsy -like retrotransposons. Species representative of the diversity of hig her plants yielded products whose sequences establish that gypsy like transposons are dispersed throughout the plant genomes. This class of plant elements has been named romani retrotransposons. The presence of both types ubiquitously in the fungi, plants and animals support thei r existence as ancient distinct lineages and subsequent, vertical radi ation.