Pathogenesis-related proteins called PR proteins ( called Pathogenesis -Related ) belong to the group of proteins activated primarily in the plant defense response to pathogens , damage caused by pests and abiotic factors . Now, on the basis of amino acid sequence homology , biochemical properties and biological activity of the 17 families stands PR proteins , often of the same family of proteins, there are different structural and / or functional units. It is known that during the attack of the pathogen -specific expression and accumulation of PR proteins is closely linked to the type of pathogen and the plant cell type and activation of the biosynthesis of certain signaling molecules : salicylic acid (SA) , jasmonic acid (JA ) and / or ethylene (ET) . Therefore, the PR proteins are often used as markers of a specific defense response induced in plant tissues . Note, however, that part of PR proteins present in plant cells constitutively , although at a low concentration . Some are stored in the cells at different stages of plant development , indicating the location of tissue- specific , others only during induction of specific stress factors induced . Despite the significant development of methods of molecular plant pathology , mechanism of action and function of many proteins PR remain unexplained . The possibility of using PR proteins , natural substances that protect plants from pathogen attack , opens new perspectives in plant biotechnology , although it should be noted that some of the PR proteins cause allergic reactions in humans. The article presents selected family of proteins PR - chitinase (PR- 4 ) , defensins (PR- 12) and thionine (PR -13) , which exhibit antifungal properties , and which is associated with the activity of the plant cell response to fungal attack nekrotroficznych and are furthermore induced specifically in response to the activation of plant defense signaling pathway dependent on jasmonic acid.