Phylogenetic relationships of the genus Secale based on the characterisation of rDNA ITS sequences

 Sequence analysis of the internal transcribed spacer of the 18S-5.8S-26S rDNA (ITS-1) region was performed in order to analyse the phylogenetic relationships of eleven taxa of cultivated and wild rye species. The ITS regions were amplified using designed primers. At least ten positive clones of each taxonomic unit were sequenced and compared. Two different ITS sequences were found in three taxa: Secale sylvestre Host, Secale strictum ssp. kuprijanovii Grossh. and Secale strictum ssp. africanum Stapf. Secale sylvestre Host was the species that showed the greatest number of comparative differences in the sequences, and was the most distant of all the taxonomic units analysed. A certain degree of variation was found among all four subspecies of S. strictum analysed. S. strictum Presl ssp. strictum was most closely related to S. strictum ssp. africanum Stapf and S. strictum ssp. kuprijanovii Grossh to S. strictum ssp. anatolicum (Boiss.) Hammer. S. vavilovii showed similarities with this group of subspecies and with the S. cereale group. No differences were found between the weed forms of S. cereale and cultivated rye. Received March 8, 2002; accepted May 31, 2002 Published online: November 20, 2002 Address of the authors: Alfredo De Bustos, Nicolás Jouve (e-mail: nicolas.jouve@uah.es), Department of Cell Biology and Genetics, University of Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.