Virulence of the Krasnodar and Dagestan populations of Puccinia hordei Otth.

Abstract

Background. Barley leaf rust is a harmful disease of barley in Russia and worldwide. In Krasnodar Territory, as well as in the Republic of Dagestan, this disease has been recorded every year. Dagestan, a geographically isolated terrain with contrasting climate conditions, harbors a diversity of wild barleys. The virulence of the Puccinia hordei Otth. population in Dagestan has not been studied, but this issue is of interest for establishing the boundaries for the North Caucasian population and for monitoring possible invasions of the pathogen’s populations from adjacent areas. Materials and methods. Virulence of the studied populations was analyzed on 15 barley cultivars and lines from international and Australian differential sets. Infectious types were registered using the Levine and Cherewick scale. Nei’s genetic diversity index (Hs) was employed to calculate the diversity of the populations in their virulence, and Nei’s genetic distance (N) for the differences between the populations. Results and conclusions. Virulence of 76 monouredinial P. hordei isolates from Krasnodar Territory and the Republic of Dagestan was analyzed. Most of the isolates were virulent to Rph1 , Rph2 , Rph3 , Rph4 , Rph5 , Rph6  +  Rph2 , Rph8 , Rph12 , Rph 21 +  Rph2 , and Rph25 . The Dagestan population had no isolates virulent to Rph7 and Rph9 , while the isolates virulent to Rph13 and Rph14 predominated. The difference between the populations scored 0.04 according to Nei, and the diversity of the Krasnodar and Dagestan populations was 0.18 and 0.32, respectively. The pathogen’s populations from both regions were saturated with isolates with high content of virulent alleles and had no significant differences in Nei’s index. At the same time, the population from Dagestan demonstrated higher diversity in the frequencies of virulence genes.