EFFECTS OF CUTICLE SOURCE AND CONCENTRATION ON EXPRESSION OF HYDROLYTIC ENZYMES BY AN ENTOMOPATHOGENIC FUNGUS, NOMURAEA-RILEYI

The effects of cuticle from larvae of Trichoplusia ni and Helicoverpa (= Heliothis) zea on expression of proteases and chitinases by germinating conidia of Nomuraea rileyi in submerged cultures were studied. Increasing the concentration of T. ni or H. zea cuticle resulted in a 13- and 15-fold increase in protease activity, respectively. Endochitinase and N-acetylglucosaminidase activity on the T. ni and H. zea substrates increased as cuticular concentrations increased to 2.5%, then stabilized or decreased thereafter. The simultaneous expression of both proteases and chitinases suggests that they are controlled by a multiple-regulatory system.