Aim of the work was specific primers (FusA1F/FusA1R) testing to study the SE2 gene controlling acid chitinase effect under stress conditions. Plants of domestic and foreign sugar beet were the material for the investigation. To confirm relationship between the SE2 gene (localized to the chromosome 3) controlling steady effect of acid chitinase and sugar beet resistance to root rot, 10 sugar beet samples were genotyped using the FusA1 molecular marker. DNA-fragments of 600 and 400 b.p.in length were revealed in each of the investigated genotypes except plants of wild beet ( Beta corolliflora Zoss .). As a result of molecular-genetic studies of the SE2 gene, eight single nucleotide polymorphism (3 T/C, 2 C/G, A/G, G/A, C/T) and 3 single nucleotide inserts (nucleotide A) were identified in plants of the breeding sample No. 9 (Sh.1). Plants of this genotype showed symptoms of fusariose infection under field conditions as well. It can be concluded that the SNPs data lead to overcoming of resistance (by changing an amino-acid unit in a polypeptide), and, as consequence, to decrease of plant adaptability.