Identification of Resistance Sources to TTKSK and TTKTK (Ug99 race group) of Stem Rust Pathogen in some Synthetic Hexaploid Wheat Genotypes

Black or stem wheat rust caused by fungal Puccinia graminis f. sp. tritici (Pgt) is the most damaging wheat disease worldwide. The race TTKSK (Ug99) and derived variants are highly virulence races of Pgt fungi that pose a serious threat to global wheat production. So far, TTKSK and TTKTK (from Ug99 group) have been reported from different parts of the country that threatening the country's food security. Identification of wheat genotypes resistant to different Pgt races and their use in breeding programs to produce resistant cultivars not only prevent the damage caused by this disease but also prevent and reduce the use of poisons in the fight against this disease. Due to the nature of production of wheat hexaploid synthetic genotypes (presence of wild ancestors in pedigree genotypes) and high genetic diversity in these genotypes finding new sources of effective resistance to Ug99 group races in these genotypes was expected. For this purpose, resistance of 346 genotypes of wheat with susceptible control (McNair 701) genotypes were evaluated with TTKSK and TTKTK races in a completely randomized block design with three replications under greenhouse conditions. Seedlings inoculation using a mixture of uridiniospor and salterol 170 at seedling stage (the 12th step of the Zadoks et al. scale). After 14 days, infection type of genotypes were recorded based on a modified method by Macintosh et al. Analysis of variance showed that there was a significant difference between the genotypes of wheat in races conditions.