WIS 2-1A: an ancient retrotransposon in the Triticeae tribe

Abstract

WIS 2-1A, the first retrotransposon found in wheat, has been recently studied and characterized. Southern hybridization experiments utilizing several species from the Triticeae revealed the presence of homologous sequences in all the taxa tested, showing high levels of interspecific variability and almost no intraspecific differentiation. Further experiments using in situ hybridization in several species showed that the retroposon was almost completely dispersed throughout the genomes tested. These results suggested that WIS 2-1A is an ancient element that probably was present in the unknown common ancestor of the Triticeae and that only under rare circumstances does it become active. DNA fragments homologous to the WIS 2-1A reverse transcriptase gene were isolated from most of the Triticeae species using PCR. The fragments obtained were sequenced and analyzed. Even though the sequence alignment was consistent with the phylogenetic studies made in the past, the genus Thinopyrum showed new evidence for a possible horizontal propagation of the retroelement. Mention of a trade name or proprietary product does not constitute a guarantee, warranty or recommendation of the product by the U.S. Department of Agriculture or the University of Missouri and does not imply its approval to the exclusion of other products that may be suitable All programs and services of the U.S. Department of Agriculture are offered on a non-discriminatory basis without regard to race, colour, national origin, religion, sex, age, marital status, or handicap.