The racial composition of Blumeria graminis f.sp. tritici in Bulgaria and the efficacy of some Pm genes

Yordanka Stanoeva

Abstract: Powdery mildew of wheat is a wide spread disease in all areas where it is grown. The race variability in the populations of Blumeria graminis f.sp. tritici in Bulgaria during 2017-2019 was investigated. The study was conducted under greenhouse conditions at climatic parameters close to be optimal for development of the pathogen. Three pure cultures were made from each sample and 12 varieties of differentials and 15 monogenic lines at stage second leaf were infected with each of the culture. After 8-10 days, the type of infection was identified. Out of the 56 samples from 28 common winter wheat varieties and lines, 168 isolates were prepared and 38 races were identified. Race 3677 had highest frequency of occurrence (16.07%), followed by races 3653 (14.29%), 3673 (11.90%) and3657 (8.93%). Race 3677 is most common in the Brushlen, Selanovtsi and Chepintsi areas. Among the samples developed during the period 2017-2019, new physiological races were not identified. The study results show that there is a great deal of genetic diversity in the pathogen population with different virulence. Ninety two genetic formulas of different virulence according to the used Pm genes were established. The most frequent genetic formula was 1.3c, 7.17 / 2.3a, 3b, 3d, 4a, 4b, 5,6,2 + 6,8,1 + 2 + 9, which accounted for 7.10 % from the developed samples. Genes Pm 3c, Pm 1, Pm 7, and Pm17 had highest efficiency against the identified races. Genes Pm 8 and Pm 5 are the least effective, and the Pm 2 + 6 gene combination is ineffective for the study period.

Keywords: Pm genes; powdery mildew; virulence; wheat

Date published: 2023-04-25