IN-VITRO ANALYSIS OF THE ROLE OF GLUCOSE-OXIDASE FROM TALAROMYCES-FLAVUS IN BIOCONTROL OF THE PLANT PATHOGEN VERTICILLIUM-DAHLIAE

Culture filtrates from Talaromyces flavus grown on glucose contained h igh levels of glucose oxidase activity, while culture filtrates from T . flavus grown On xylan contained negligible glucose oxidase activity, Culture filtrates from T. flavus grown on both media contained comple x protein profiles, However, only culture filtrates from T. flavus gro wn on glucose inhibited germination of microsclerotia of Verticillium dahliae in in vitro inhibition assays, A polyclonal antiserum preparat ion, pABGO-1, raised against purified glucose oxidase from T. flavus w as highly specific for glucose oxidase, Only one protein band in cultu re filtrates (from glucose medium), migrating at 71 kDa, was detected in Western blots (immunoblots) with this antiserum, This band comigrat ed with purified glucose oxidase, No bands were detected in culture fi ltrates from the xylan medium, Glucose oxidase was removed via immunop recipitation from culture filtrates of T. flavus grown in glucose medi um, resulting in filtrates which no longer inhibited in vitro microscl erotial germination, When glucose oxidase-depleted filtrates were amen ded with purified glucose oxidase from T. flavus, the ability to kill microsclerotia in vitro was restored to original levels, We conclude t hat glucose oxidase is the only protein in culture filtrates of T. fla vus responsible for inhibition of germination of microsclerotia of V, dahliae.