MOLECULAR TOOLS FOR STUDYING SEPTORIA TRITICI VIRULENCE
S PNINI-COHEN1, A ZILBERSTEIN1 and Z EYAL1,2
1Department of Plant Sciences, and 2Institute for Cereal Crops Improvement (ICCI), George S Wise Faculty of Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
Background and objectives
Results and conclusions
The 398D25 mutant (HygR, GUS+) showed a significant shift from low to high virulence on Seri 82. Molecular analysis showed that the D25 mutant contains a single insert with the hph and uidA genes, probably resulting from a recombination event between the homologous regions of the two plasmids that occurred prior to insertion into the fungal genome. The genomic margins of the integration locus were isolated by inverse PCR and used to construct plasmid vectors for a targeted insertion strategy designed to verify the linkage between the mutated locus and the virulent phenotype. The use of genomic fragments smaller than 1 kb as potential sites for the double-recombination events proved unsuccessful, leading only to random insertion events in unrelated genomic loci. When the isolate ISR398 was transformed with a plasmid that carried 1.3- and 1.7-kb genomic flanking regions, targeted insertions were obtained at a frequency of 25%. Pathogenic assays with the putative mutants are under way.
This approach has paved the way for the generation of additional mutants involved in events associated with the wheat S. tritici interaction.