Genetic diversity among old Portuguese bread wheat cultivars and botanical varieties evaluated by ITS rDNA PCR-RFLP markers

Abstract

In contrast to the highly conserved 18S-5.8S-25S ribosomal RNA (rRNA) genes, the ribosomal DNA (rDNA) spacers, such as the internal transcribed spacer (ITS) and the intergenic spacer (IGS) present high variability and faster rates of evolution (Baldwin et al. 1995; Barker et al. 1988). ITS length variants have been reported for several plant species, including hexaploid wheat (Baldwin et al. 1995; Alvarez and Wendel 2003; Nalini et al. 2007; Saini et al. 2008). The ITS polymorphism might occur at the genus, species or individual levels, making it useful for phylogenetic, evolutionary and biogeographical studies. The present study undertakes a genetic diversity analysis of an old Portuguese bread wheat collection, comprising of 48 cultivars belonging to nine botanical varieties, based on the ITS rDNA variation. This collection constitutes an excellent repository of germplasm in Portugal. Additionally, we intend to test the reliability of the ITS rDNA PCR-RFLP markers for defining phylogenies among bread wheat botanical varieties which could be helpful for designing wheat breeding strategies.