Effective resistance to leaf rust in spring bread wheat accessions among recent additions to the VIR collection

Abstract

Background . One of the most important factors causing decreases in the yield and grain quality of bread wheat ( Triticum aestivum L.) is the incidence of fungal diseases, including leaf rust (causative agent: Puccinia triticina Erikss.). Due to microevolutionary processes in pathogen populations, cultivars quite often lose their resistance, so a constant search for new sources and donors of effective resistance genes is required. The aim of the work was to study juvenile (seedling) and adult resistance to leaf rust in new accessions of spring bread wheat from the collection of the N. I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). Materials and methods . The research material included 334 spring bread wheat accessions from 30 countries that were added to the VIR collection from 2010 to 2015. Juvenile resistance was studied in the environments of Pushkin Laboratories of VIR. Intact seedlings were inoculated with P. triticina uredospore suspension. A complex population of leaf rust causative agent (mixture of uredospores from susceptible wheat cultivars in the Northwestern region of Russia maintained on leaf segments of cv. ‘Leningradka’) was used as inoculum. Reaction type scores were evaluated 14 days after inoculation according to the E. B. Mains and H. S. Jackson scale. Adult resistance of wheat to leaf rust was assessed on experimental plots of the All-Russian Research Institute of Plant Biological Protection and All-Russian Research Institute of Phytopathology against artificial infection backgrounds. Leaf rust intensity was evaluated during the period of maximum disease development in an accession’s milky ripeness phase according to the percentage of the affected flag leaf surface. Results and conclusions . Comparison of the disease development under field conditions in Moscow Province and Krasnodar Territory showed significant differences between two pathogen populations in their genotypic composition. Studying leaf rust resistance, we identified 15 accessions with high levels of juvenile resistance to the pathogen population from the Northwest of Russia; 119 and 129 cultivars demonstrated adult resistance to the populations from Moscow Province and Krasnodar Territory, respectively; 38 accessions possessed highly effective adult resistance to leaf rust in two regions of Russia. These accessions are undoubtedly promising for leaf rust resistance breeding in the Central and North Caucasus regions of Russia.