Diagnosis of soil-borne fungal agents that cause problems in Kazakhstan wheat cultivation areas

Wheat is the most common agricultural product among cultivated crops. Soil-borne diseases constitute an important group among abiotic and biotic stress factors that threaten wheat production. Diseased plant samples containing symptoms in underground tissues were collected from 65 different fields in the central, eastern and southeastern regions of Kazakhstan in the 2019 growing season. Pathogenic fungal agents were determined by conducting etiological studies on plants showing symptoms of wheat root and crown rot. A total of 1221 fungal isolates were obtained in the studies carried out. DNA sequence analyses based on internal transcribed spacer (ITS) and translation elongation factor-1 alpha (EF1-α) loci were performed to confirm the species identification of the isolates for which classical identification studies were conducted. Bipolaris sorokiniana (44.80%) and Fusarium acuminatum (20.39%) were the dominant fungal species isolated in 86.15% and 66.15% of the studied areas, respectively. These species were followed by F. equiseti (10.16%) and Curvularia spicifera (7.62%), Fusarium culmorum (4.75%), F. oxysporum (4.10%), F. redolens (2.38%), Rhizoctonia solani AG2-1 (1.06%), Nigrospora oryzae (0.98%), C. inaequalis (0.90%), F. pseudograminearum (0.74%), F. flocciferum (0.74%), Macrophomina phaseolina (0.66%), F. cf. incarnatum (0.33%) and F. torulosum (0.16%). Three Fusarium isolates, representing 0.25% of the total, did not match with any known species in the literature. Pathogenic characterizations of 74 isolates representing 16 species were performed with Triticum aestivum cv. Seri 82. According to the results, Fusarium culmorum and F. pseudograminearum, Fusarium sp., B. sorokiniana, R. solani, F. redolens, C. spicifera, C. inaequalis and N. oryzae were found to be virulent. In contrast, other species were found to be non-pathogenic. The study findings showed the presence of a wide variety of fungal species that pathogenically and symbiotically colonize the crown and root tissues of wheat in Kazakhstan. The study is the first report of F. culmorum, F. pseudograminearum, Fusarium sp., B. sorokiniana, C. spicifera, and C. inaequalis on wheat in Kazakhstan.