Abstract
Wheat stem rust caused by Puccinia graminis f. sp. tritici Eriks. & E. Henn. (Pgt), is a major disease that has been effectively controlled using resistance genes. The appearance and spread of Pgt races such as Ug99, TKTTF, and TTTTF, which are virulent to most stem rust-resistant genes currently deployed in wheat breeding programs, renewed the interest in breeding cultivars resistant to wheat stem rust. It is therefore important to investigate the levels of resistance or vulnerability of wheat cultivars to Pgt races. Resistance to Pgt races 21C3CTHQM, 34MKGQM, and 34C3RTGQM was evaluated in 136 Chinese wheat cultivars at the seedling stage. A total of 124 cultivars (91.2%) were resistant to the three races. Resistance genes Sr2, Sr24, Sr25, Sr26, Sr31, and Sr38 were analyzed using molecular markers closely linked to them, and 63 of the 136 wheat cultivars carried at least one of these genes: 21, 25, and 28 wheat cultivars likely carried Sr2, Sr31, and Sr38, respectively. Cultivars “Kehan 3” and “Jimai 22” likely carried Sr25. None of the cultivars carried Sr24 or Sr26. These cultivars with known stem rust resistance genes provide valuable genetic material for breeding resistant wheat cultivars.
Highlights
Wheat stem rust caused by Puccinia graminis Per. f. sp. tritici Eriks. & E
The results indicated that only 5–15% of the wheat accessions grown globally were resistant to Ug99, and only two of the 118 Chinese wheat cultivars (“Jimai 20” and “Linmai 6”) were resistant to Ug99
A total of 124 (91.2%) wheat cultivars were resistant to the three races (ITs 2, 1+, or lower) while the remaining 12 were susceptible (ITs 3, 3, 3+, and 4) (Fig. 2)
Summary
Wheat stem rust caused by Puccinia graminis Per. f. sp. tritici Eriks. & E. Wheat stem rust caused by Puccinia graminis Per. f. A new race of the stem rust pathogen (Ug99), identified in Uganda in 1999 and highly virulent to resistance gene Sr31, was designated as TTKSK under the North American nomenclature system (Pretorius et al, 2000). Virulence of TTKSK to other important stem rust resistance genes (e.g., Sr24, Sr36, Sr9h, Sr31 + Sr24, Sr31 + Sr36, and Sr31 + SrTmp) was detected (BGRI, 2017; Jin et al, 2008, 2009; Pretorius et al, 2012; Rouse et al, 2014), and 13 variants of Ug99 have been documented across wheat growing regions in 13 countries (Food and Agriculture Organization of the United Nations (FAO), 2017).
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