Investigation of seedling resistance of CIMMYT wheat germplasm to Puccinia graminis f. sp. tritici races

Stem or black rust caused by Puccinia graminis f. sp. tritici (Pgt) is one of the most destructive wheat diseases in the world, including Iran. Investigation of virulence factors on wheat resistance genes, identification of resistance sources to stem rust among host genotypes and determination of effective resistance genes in resistant wheat genotypes are the requirements of using genetic resistance (production of resistant cultivars) as the most efficient and healthy way to control this disease. To assess the seedling resistance of 30 wheat genotypes, which produced CIMMYT Center (International Maize and Wheat Improvement Center), and introduced as resistance sources to stem rust was investigated with six different Pgt races base on randomized complete block design with three replications. Race analysis of Pgt isolates was done to identify of their virulence on resistance genes (Sr) of stem rust at the greenhouses of the cereal section of the Seed and Plant Improvement Institute. The results indicated that the races were TKTTF, TTTTF, PKSTC, TTRTF, TKSTF and PTRTF. Genotypes carrying the genes Sr22, Sr24, Sr26, Sr31, Sr32, Sr33 and Sr40 were resistance against all the Pgt races, and are introduced as the differential cultivars with effective Sr resistance genes. Genetic resistance components including infection type and latent period for each genotype were recorded under greenhouse conditions. The results of the genetic resistance components showed the existence of phenotypic variation in the response of genotypes to stem rust races. Resistant genotypes identified in this study (genotypes 4, 5, 6, 7, 8, 9, 11, 13, 14, 16, 17, 18, 20, 21, 22, 25, 26, 27, 28 and 29) can be used as seedling resistance resources in national wheat breeding programs for genetic resistance to stem rust in different climates of the country.