Detection of Ug99 (TTKSK) of wheat stem rust fungus and new virulence races of Puccinia graminis f.sp. tritici in Egypt

Abstract

Wheat  stem  rust  caused  by Puccinia graminis  f. sp. tritici (Pgt), is  one  of   the   most  destructive  diseases  of   wheat. Survey of stem rust was carried out during 2014 and 2015 seasons in Kafrelsheikh, Sharqia, and Nubaria governorates in Egypt. The physiologic races of stem rust were determined on seedlings of the standard wheat stem rust differentials following the international system of nomenclature. Results indicated the occurrence of twelve races, three in the Ug99 race group; TTKST, TTKTK, TTKSK from Al-Sharqia, Sakha and from Nubaria, respectively. The rest of races are not belonging to the Ug99 race group which was detected during the two seasons. In addition, situation was studied on monogenic Sr's lines against stem rust disease under field conditions. Sr2, Sr24 and Sr26 were highly effective for resistance in both seasons.  While, Sr27 and Sr31 either was ineffective in some years, or did not confer adequate resistance. Four Egyptian wheat germplasm namely Giza164, Sakha93, Sakha94 and Sids1 with significantly low ACI, AUDPC, rAUDPC and RRI were identified. Also, these genotypes showed low disease severity moderately resistance (MR) infection type in both seasons. First occurrence of the Ug99 race of wheat stem rust (Pgt) to Egypt in 2014/15. The obtained results would serve as a fruitful tool in wheat breeding program directed for disease resistance.