Pathogenic Types And Virulence Frequency Of Puccinia Triticina In China In 2007

Wheat is very important crop in China. Wheat leaf rust caused by Puccinia triticina is one of the most important diseases and can cause significant yield and economic losses. Using resistant cultivars to leaf rust is the most economical and effective approach of controlling this disease. Variation of population composition of the Puccinia triticina caused the loss of leaf rust resistance in wheat cultivars. Therefore, survey of the pathotypes and the frequency of virulence genes in China play an important role in breeding new resistant cultivars and deploying resistant wheat cultivars.Five hundred and fifteen collections of Puccinia triticina were obtained from 17 provinces or city of China in 2007. Five hundred and thirty single-uredinial isolates collected were tested for pathogenicity using 42 lines with different leaf rust resistance genes. Two hundred and thirty virulence phenotypes of Puccinia triticina were detected, among which THST was the most predominant one consisting of 5.1% of the population. THSS (3.8%), PHTT (3.6%), PHRT (3.4%), THQT (3.0%), THTT (2.6%), PHST (2.3%), THJT (2.1%) and PCSP (2.1%) also occurred at a relatively high frequency. The different main phathotypes and virulence frequency are found in the various provinces of China.The results also showed that the average virulence frequency of V1, V2c, V3, V3bg, VB, V10, V11, V14a, V14b, V16, V25, V26, V33 and V33+34 were above 80%. Lower than 30% isolates in the population were virulent to Lr9, Lr19, Lr24, Lr38, Lr39, Lr40, Lr41, Lr42 and Lr43, respectively, suggesting that these genes be applicable in wheat breeding for resistance. The average virulence frequency of V2b, V3ka, V14ab, V17, V18, V29, V20 and V50 were 60%-80% and others were 30%-60% among all China, and the corresponding resistance genes can be used in gene deployment and pyramiding of several resistance genes.Virulence polymorphism clustering of Puccinia triticina in China in 2007 was constructed by software NTSYS2.10. The result indicated that the virulence similarity of the isolates was higher. Virulence similarity correlated to areas could also be deduced from the distribution of the isolates in the virulence polymorphism clustering.