Postulation of Stem Rust (Puccinia graminis f.sp tritici) Resistance Genes in Ethiopian Durum Wheat Cultivars and Lines

Wheat (Triticum aestivum L.) is one of the most important staple crops in Ethiopia, but its production is significantly challenged by stem rust (Puccinia graminis f.sp. tritici). While fungicides can help to manage this disease, their cost and environmental impact pose serious concerns. An alternative and environmentally friendly approach is the use of host resistance, which is also more cost-effective. However, relying on cultivars with the same resistance genes can increase the risk of developing virulent races of the pathogen. Therefore, understanding the resistance genes in wheat cultivars is crucial for deploying varieties with different resistance genes to minimize damage. This study aimed to postulate resistance genes in some Ethiopian durum wheat cultivars and lines. Postulation of wheat stem rust resistance genes was conducted by challenging seedlings of 20 durum wheat varieties; 25 durum wheat lines and 20 monogenic lines by eleven races of Puccinia graminis f.sp. tritici (pgt) (TKTTF, TTKSK, TRTTF, JRCQC, RRTTF, TTRTF, TKPTF, TKKTF, TTKTF, TTKTT and TTTTF). Infection types were evaluated 14 days post-inoculation using a 0-4 scale, where scores of 0-2 indicated low infection (incompatible reaction) and scores of 3-4 indicated high infection (compatible reaction). Infection types produced on twenty monogenic lines and test entries were compared to postulate probable presence of respective resistance genes in the genotypes. The study identified five resistance genes (Sr7b, Sr10, Sr38, Sr31, and Sr11) and some unidentified genes in Ethiopian durum wheat cultivars and lines. Therefore, these genes could be used to enhance the genetic diversity of stem rust resistance in wheat for better protection against virulent races of the pathogen.