Identification of physiological races of Puccinia graminis f.sp. tritici in Iraq

Abstract

Stem rust has become a major cause for concern with the emergence of race Ug99 in Eastern Africa. The potential impact of the disease is particularly serious in Iraq. The current study was conducted to identify the physiological races of Puccinia graminis f.sp.tritici (Pgt), the causal agent of stem rust. Single pustules of stem rust samples collected from different wheat fields from Sulaimani, Erbil, Diala, Nineveh and Babylon were separately multiplied on the susceptible cultivar cv Morocco. Seven-day-old seedlings of the North American stem rust
differential set inoculated with urediniospores of each pathogen isolate; the inoculated plants were scored two weeks after inoculation using the infection type scale described by Stakman. Race analysis indicated prevalence of five races of the pathogen. Race TKTRC was prevalent in Sulaimani; RKJTF in Erbil; TKTTC in Nineveh; PRJSC in Diala and KRKSCin Dheqar.The resistance genes Sr24 and Sr31 were effective against all Pgt isolates, while resistance genes Sr7b, Sr9g, Sr9b, Sr30, Sr9a, Sr9d, SrMcN were ineffective against all the isolates. None of the identified races of Pgt belonged to race Ug99 or members of this race group. Real-time PCR analysis of DNA extracted from dead spores,
representing each of the Pgt races, at USDA-ARS cereal disease Lab, St Paul, Minnesota confirmed these results.

 

 

DOI:10.25174/2249-4065/2017/66959