During plant-pathogen interactions, the metabolism of the host plant is modified, which results in an increase in energy and the production of compounds that are a carbon source, such as sucrose, glucose, and fructose. In addition to being the main transport form of carbohydrates in plants, sucrose, as well as its components fructose and glucose, are important signaling molecules involved in signaling pathways that activate the plant's defense response. This research aims to determine the role of the sucrolytic pathway in the interaction of winter wheat and phytopathogenic fungi of the genus Fusarium, which causes Fusarium head blight (FHB). This disease affects commercial crops worldwide and represents a global economic and agricultural problem. The research was conducted on six winter wheat varieties, where the activities of three isoforms of invertase and two isoforms of sucrose synthase (SuSy) were measured. Varieties classified as resistant, Vulkan and Galoper, had increased activities of SuSy A and B enzymes, cytoplasmic and vacuolar invertases, while the susceptible variety Golubica had reduced activities of these enzymes. Increased activities of enzymes of the sucrolytic pathway in resistant varieties indicate effective cell signaling, which contributes to the defense response of wheat to pathogen attack