Identification of durum wheat (Triticum turgidum ssp. durum L.) germplasm from Iran, Italy, Argentina, and Bulgaria with resistance at the seedling stage to race Ug99 of Puccinia graminis f. sp. tritici

We evaluated seedling responses of a diverse set of durum wheat accessions originating from Serbia, Afghanistan, Portugal, Bulgaria, Argentina, Iraq, Italy, and Iran to Puccinia gramini f. sp. tritici. Morphologically superior durum accessions (118 entries) were screened against two isolates of the pathogen from Lorestan and Khuzestan provinces of Iran previously typed as TTKSK (Ug99) at the seedling stage. The putatively resistant entries were tested in replicated experiments along with germplasm known to possess resistance genes, such as Amigo, Fleming, Eagle, Agatha, Sage, and RL5711. We identified putatively novel sources of resistance to Ug99, characterized by infection types 0, 0;,;1,;2,;1+, and 22+. We also observed a previously unreported highly susceptible seedling response in germplasm containing the gene Sr13 to Ug99. The resistant durum accessions include Wc-47208 from Bulgaria (IT = 0;), Wc-47191 from Argentina (IT = 0;), Tn-12716 from Iran (IT =;1), and P.S.No18 and P.S.No19 from Italy (IT =;2 or;1+). This study emphasized that local landraces in national gene banks are rich in disease resistance genes and may be useful in breeding efforts to combat Ug99 stem rust.