Evaluation and identification of stem rust resistance genes Sr2, Sr24, Sr25, Sr26, Sr31 and Sr38 in wheat lines from Gansu Province in China

Wheat stem rust, caused by Puccinia granimis f. sp. tritici, severely affects wheat production, but it has been effectively controlled in China since the 1970s. However, the appearance and spread of wheat stem rust races Ug99 (TTKSK, virulence to Sr31), TKTTF (virulence to SrTmp) and TTTTF (virulence to the cultivars carrying Sr9e and Sr13) have received attention. It is important to clarify the effectiveness of resistance genes in a timely manner, especially for the purpose of using new resistance genes in wheat cultivars for durable-resistance. However, little is known about the stem rust resistance genes present in widely used wheat cultivars from Gansu. This study aimed to determine the resistance level at the seedling stage of the main wheat cultivars in Gansu Province. A secondary objective was to assess the prevalence of Sr2, Sr24, Sr25, Sr26, Sr31, and Sr38 using molecular markers. The results of the present study indicated that 38 (50.7%) wheat varieties displayed resistance to all the tested races of Puccinia graminis f. sp. tritici. The molecular marker analysis showed that 13 out of 75 major wheat cultivars likely carried Sr2; 25 wheat cultivars likely carried Sr31; and nine wheat cultivars likely carried Sr38. No cultivar was found to have Sr25 and Sr26, as expected. Surprisingly, no wheat cultivars carried Sr24. The wheat lines with known stem rust resistance genes could be used as donor parent for further breeding programs.