Race and Virulence Analysis of Puccinia triticina in China during 2011 to 2013

Wheat leaf rust, caused by Puccinia triticina, is a common fungal disease of wheat in China. In order to identify races and determine the individual virulence of isolates in different wheat-growing regions in China, leaf rust samples collected from 18 provinces in 2011 to 2013 were tested on 37 Thatcher near-isogenic lines each carrying a different single leaf rust resistance gene. A total of 158 races were identified. Races THTT (19.5%), THTS (16.9%), PHTT (7.7%), THIS (5.0%), THJT (4.2%), and PHTS (4.0%) were the most predominant races in 2011 to 2013. All of these races were avirulent to resistance genes Lr9 and Lr24. The two most frequent races, THTT and THTS, were widely distributed. The frequencies of the isolates with virulence to Lr1, Lr2c, Lr3, Lr16, Lr26, Lr17, LrB, Lr10, Lr14a, Lr3bg, Lr1 4b, Lr33, Lr37, and Lr50 exceeded 90%. Frequencies of virulence to Lr2a, Lr3ka, Lrl , Lr30, Lr2b, and Lr32 exceeded 70% but were less than 90%. Frequencies of virulence to Lr18, Lr2.1, Lr15, Lr23, Lr33+34, Lr36, Lr39, and Lr44 were below 70%, whereas the frequency of virulence to Lr25 was less than 1%. All isolates were avirulent to Lr9, Lr19, Lr24, Lr28, Lr42, Lr29, Lr38, and Lr47. The identified races and individual virulence frequencies provide a basis for selection of effective leaf rust resistance genes for use in breeding programs and can also provide information for the study of race evolution of P. triticina.