Detection of molecular polymorphism of Puccinia triticina from wheat in Romania.

Leaf rust of wheat (Triticum aestivum L.) is caused by Puccinia triticina Ericks and is a common disease of this plant species in northwest, southern, southeast, and eastern Europe. It has been shown that the severity of leaf rust increased in the last years in many regions of Europe and highlighted the need for selection of wheat cultivars with race specific resistance genes. In order to select wheat resistant lines and develop efficient management programs for disease control, the characterization (phenotypic and molecular) of leaf rust races isolated from specific area is an important step of researches. To date, several molecular markers have been used to describe variation in P. triticina in Europe and worldwide. The aim of this work was to study the molecular diversity of P.triticina collected from Romanian fields (Fundulea, Livada, Pitesti). Single-uredinial isolates were obtained from several populations of P.triticina and used for inoculation of detached wheat leaves cultivar F133. Genomic DNA was isolated from 20 fresh single-uredinial samples (2-10 mg spores) and from eight populations of P. triticina urediniospores (10-20 mg spores) using OmniPrep for Fungus kit. The molecular polymorphism was evaluated through RAPD (with eight decameric primers) and by using 15 SSR primers and two ISSR primers. Results showed a reduced polymorphism at population level, but not identity, as indicated the RAPD analysis. No more than two alleles were detected in the leaf rust populations with the SSR markers used in experiments according to our separation protocol. Differences in the SSR loci were detected in the single-uredinial isolates. Similar results were obtained with ISSR primers: ISSR 17898A primer allowed the detection of the highest polymorphism among the individual isolates. Evidence for molecular variability between single urediniospores isolates will be correlated with the virulence phenotypic analysis in further studies.