OGs are biologically active compounds that have regulatory function in plant cells, affecting various processes including immune responses. Most of the OGs is released as a result of enzymatic degradation of polysaccharides, which are component of plant cell walls. Pectins (polysaccharides that are part of the primary cell wall, rich in D-galacturonic acid residues) are a source of OGs. OGs induce biochemical changes related to resistance to pathogens, e.g., synthesis of phytoalexins, changes in cell wall structure caused by accumulating various substances
(callose or lignin).