Differential in vitro and in vivo effect of barley cysteine and serine protease inhibitors on phytopathogenic microorganisms

► Protease inhibitors from plants are involved in defence mechanisms against pests and pathogens. ► Thirteen cystatins (HvCPI-1 to 13) and the trypsin inhibitor BTI-CMe are protease inhibitors from barley. ► Barley cystatins and BTI-CMe are able to inhibit the in vitro growth of phytopathogenic fungi. ► Barley cystatins and BTI-CMe are not able to inhibit the in vitro growth of phytopathogenic bacteria. ► Transgenic plants expressing the HvCPI-6 or BTI-CMe proteins are not resistant to fungal and bacterial pathogens.