Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

INTERNAL TRANSCRIBED SPACERS (ITS) FROM NUCLEAR RIBOSOMAL DNA IN TRITICUM DICOCCUM SCHÜBLER SELECTED LINES

RIZZO M.*, MANZO M.*, BATTAGLIA A.**, BERNARDI R.*, STEFANI A.**, DURANTE M.*

* Dipartimento di Biologia delle Piante Agrarie, Sez. Genetica, Via Matteotti 1/B, 56124 Pisa

mdurante@agr.unipi.it

** Scuola Superiore di Studi Universitari e Perfezionamento S. Anna, Via Carducci, Pisa

Triticum dicoccum Schübler, ITS, ecotypes identification

Seven lines of T. dicoccum Schübler have been selected according to their agro-morphological characteristics from an old cultivated heterogeneous population from Garfagnana (Tuscany) (Stefani et al., 1997).

In order to develop specific markers to associate with the phenotypic characters, we have analysed both biochemical and DNA components. In this work we present the experimental results concerning the internal transcribed spacer of the nuclear ribosomal DNA (ITS1 and ITS2 sequences). Nuclear ribosomal DNA in plants is organised in clusters of tandem middle repetitive elements separated by an intergenic spacer. Each element contains three structural elements (18S, 5,8 S and 25S): ITS1 separates 18S from 5,8S, and ITS2 separates 5,8S from 25S. ITSs are molecular markers often used in low level taxonomy and in intraspecific variability dissection due to the facility of analysis and the high informative content.

The common use of this molecular markers is based on the assertion of sequence identity of all the copies of the repetitive units, as a consequence of a process called gene conversion leading to sequence homogenisation (Dover, 1982), but in our case we have observed a couple of PCR amplicons in all the examined samples probably due to the A and B genomes that constitute this plant. For this reason we have firstly analysed and compared a consensus sequence to be used for a preliminary phylogenetic study.

Moreover, we have separated the two amplicons by polyacrylamide gel electrophoresis for the determination of the respective sequences. This type of investigation could represent an original tool for the use of the ITS markers as sequence specific codominants, for testing the putative genome origin and for the intraspecific variability assessment.