Virulence and pathogenic variability of wheat leaf blotch (Zymoseptoria tritici) isolates in Oromia, Ethiopia

Abstract

Abstract Wheat leaf blotch caused by Zymoseptoria tritici (Zt) is a fungal disease that poses a severe danger to wheat production worldwide. Knowing the virulence diversity of this pathogen is crucial for taking effective control measures. However, there have been a few studies on Ethiopia pathogenic variability and pathotypes based on physiological specialization. Therefore, the goal of this study was to look at the virulence, spectrum, and population variability of Zt isolates. In a completely randomized design, 43 isolates in three replications were tested for their virulence and pathotypes against 7 wheat differential lines. The least significant difference method was used to identify specific virulence; whereas, pathotypes, principal components, and cluster analysis were used to study the pathogenic diversity. Then, virulence assay detected 41 differential lines specific virulence and 220 differential lines specific avirulence, among all (n = 301) interactions based on pycnidia parameter. Some of the isolates showed a considerable virulence spectrum on 4 (57.1%) and 5 (71.4%) differential lines based on pycnidia and leaf necrosis respectively; but, most of them were partial virulent on the differential lines. Based on pycnidia parameter: EtA-11, EtSh-1, EtSh-2, EtSh-4, and EtA-19 isolates expressed the virulent reaction on 3–4 differential lines; hence, useful for germplasm screening. Over, from this parameter, 25 pathotypes were ensued in which indicated 58.1% pathogenic diversity; moreover, the principal component analaysis detected 62.2% pathogenic diversity of Ethiopian isolates. Therefore, further virulence variability investigations employing isolates*wheat species specificity and molecular analysis are important. Wheat breeders and wheat farmers would find the results from this study extremely useful for making informed decisions on how to manage Zt disease. Again, it is crucial to examine the virulence diversity of Zt isolates using pathotype and principal component analysis.