Disclosed are polynucleotides that encode a beta-glucosidase belonging to the plant protein class of family 1 glycoside hydrolases. Furthermore described are recombinant nucleic molecules and vectors containing these polynucleotides and host cells, preferably plant cells that are genetically engineered with these polynucleotides. In addition, transgenic plants are disclosed which show an increased activity of the beta-glucosidase described, preferably leading to an improved resistance against plant pathogens. In another aspect, the present application discloses screening methods for identifying a substrate for said betaglucosidase and methods for the production of plant protection compositions from such substrates or hydrolysis products thereof. Furthermore, methods and uses are disclosed which apply the polynucleotides encoding the beta-glucosidase described in order to improve resistance in plants against plant pathogens.