The Study of Genetic Polymorphism of Fungal Pathogens Using iPBS Assays

Abstract

Species of the genus Alternaria are widely distributed as saprophytes on plant residues, as well as pathogens of various plant species. On wheat seeds, Alternaria fungi are localized in the endosperm and fruit shells, causing symptoms of "black germ" disease, and are a dominant component of the wheat seed microbiome. Recently, due to the high potential danger of these fungi, much attention has been paid to the study of the genetic variability of populations that exist in certain climatic conditions. Using retrotransposon sequences as markers increase knowledge about phylogenetic relationships within populations of phytopathogenic fungi, as well as their biodiversity.

The iPBS (inter-priming binding sites) method used in this work was applied to detect genetic polymorphism of isolates of the genus Alternaria, as the most frequently encountered genus (the frequency of isolation was more than 50%). The isolates were isolated from wheat seeds that were cultivated in various ecological regions. The 4 iPBS primers used in this study amplified 387 fragments, 352 of which were polymorphic. The level of detected polymorphism varied from 66% when using primer 2224 to 100% when using primer 2242. The information content index of the PIC (polymorphism information content) primers varied in the range of 0.894-0.987. Analysis of genetic polymorphism revealed significant genetic variability among fungal isolates. Genetic analysis of amplification profiles of isolates of fungi of the genus Alternaria conducted using the GenAlex 6.5 software differentiated all isolates into 2 large groups. Isolates of A. infectoria were isolated in a separate cluster. Isolates of A. alternata and A. tennuissima were grouped in a different cluster depending on the species. Research results show that the iPBS method is highly effective for the genetic differentiation of phytopathogenic fungi at both intraspecific and interspecific levels.