COMPREHENSIVE STUDY OF POTATO PHYTOPATHOGENS IN THE KARAGANDA AND AKMOLA REGIONS OF KAZAKHSTAN

Abstract

Potato (Solanum tuberosum L.) is one of the most important agricultural crops in Kazakhstan; however, its productivity is substantially limited by phytopathogenic organisms. The aim of this study was to investigate the diversity of fungal and bacterial pathogens and phytonematodes associated with potato tubers collected from the Akmola and Karaganda regions. The objectives included the sampling and phytopathological analysis of tubers from various potato varieties, the isolation and cultivation of microorganisms via primary inoculation on nutrient media, the acquisition of pure pathogen cultures, their morphological and microscopic identification, as well as molecular genetic analysis of the isolated strains for species-level identification. The frequency of occurrence of the identified phytopathogens was assessed depending on the varietal affiliation of the studied samples. A total of 21 samples representing 10 potato cultivars were analyzed using conventional microbiological, microscopic, and molecular genetic methods. Pure cultures were isolated and identified based on morphological and microscopic characteristics. Their species identity was confirmed by molecular genetic identification using ITS region sequences of fungal ribosomal DNA and the 16S rRNA gene of bacteria. The dominant pathogens were Fusarium spp. (up to 95%) and Rhizopus spp. (up to 50%), while Alternaria alternata (up to 25%), Colletotrichum coccodes (up to 25%), Phytophthora spp. (up to 20%), and Erwinia spp. (up to 15%) occurred less frequently. The sequencing results confirmed the presence of Fusarium solani, Rhizopus stolonifer, Alternaria alternata, Colletotrichum coccodes, and Erwinia chrysanthemi. Additionally, phytonematodes morphologically consistent with Ditylenchus destructor were detected in samples of the Gala, Vega, Miya, and Arizona cultivars. It was established that the highest level of infestation was observed in the Arizona cultivar, a moderate level in the Gala cultivar, while the Vega and Miya cultivars exhibited minimal infection. The obtained results indicate the complex nature of potato damage, with a predominance of fungal etiology and a significant role of phytonematodes in tissue damage and the development of secondary infection.