Virulence Structure and Diversity of Puccinia coronata f. sp. avenae P. Syd. & Syd. in Poland During 2013 to 2015

Abstract

The crown rust fungus Puccinia coronata f. sp. avenae P. Syd. & Syd. (Pca) attacks cultivated oat and its wild relatives, causing significant losses to the crop worldwide. Although understanding the origin and dynamics of the pathogen’s diversity are critical to developing methods for its control, there is little relevant data on Pca virulence diversity in Europe, the global centre of oat production. The goal of the present study was to analyse the diversity of Pca populations in Poland in 2013-2015 based on their ability to overcome currently available host resistance Pc genes. Pca isolate virulence was evaluated on a panel of lines containing 26 major resistance genes of oat. The isolates were able to overcome from one to sixteen resistance genes each, with most isolates being virulent on five to seven lines. In all years a very high level of crown rust pathotype diversity was observed, with Simpson and Evenness indices of 0.99. In total, 156 different pathotypes were detected with no prevalent pathotype in any of the three years analyzed. The results showed that the virulence level of P. coronata isolates was relatively low for each year studied (21% on average), most likely due to the low take-up of Pc genes in Polish oat cultivars, meaning that many sources of resistance are still effective against Pca races occurring in Poland. The long range dispersal of Puccinia spores, supported by the availability of wild, weedy and cultivated Avena species, makes it likely that the virulence profile seen in Poland is representative of much of central Europe and beyond.