Mutations in Puccinia triticina pathotypes in wheat rust repository in India

Two new variants of Puccinia triticina were identified in the repository cultures of pathotypes 20 (5R27 = SGQPL) and 107‐1 (45R35 = JCGPL) being maintained as live cultures in the national repository at Shimla, Himachal Pradesh, India, for 87 and 24 years, respectively. Mixtures of infection types were observed on Lr15 in one pathotype 20 whereas on Lr3 in 107‐1. The single pustule isolations and further purification in both the cases yielded two new pathotypes designated as 20‐2 (57R27 = SHKPL) and 57 (45R39 = KGTPL). The pathotype 20‐2 was one‐step gain in virulence to Lr15 in mother culture of pathotype 20. Contrarily, the second new pathotype though close to 107‐1 (with additional virulence to Lr3), however, resembled standard race 57 of the classical differentials. The difference in virulence on one gene as compared to the respective mother culture and their non‐detection from the field samples reflects mutation for virulence in situ. To confirm the novelty of new pathotypes, detailed studies were conducted on differentials, avirulence/virulence on Lr genes, DNA polymorphism using SSR markers, and the results are presented in this publication. The new variants have been added to the live culture collection of the centre and designated as PrtI 57 and PrtI 20‐2.