The effect of chitooligosaccharides (CHOSs) with a molecular weight of 5-10 kDa and a degree of acetylation (DA) of 65 and 13% at a concentration of 1.0 mg/L on the expression of the TC151917 gene, which encodes wheat anionic peroxidase, and the activity of "anionic" isoperoxidases in common wheat plants infected with Septoria nodorum Berk.--the causative agent of septoriosis. Treatment with CHOSs with a 65% DA and infection promoted the transcription of the anionic peroxidase gene and increased the enzymatic activity of the anionic peroxidase with an isoelectric point of 3.5 in soluble and ion-bound to cell walls protein fractions. Chitooligosaccharides with a 13% DA change these parameters to a lesser extent. These data suggest the importance of the degree of acetylation of CHOSs in the development of immune responses of wheat with the involvement of peroxidases.