PARTIAL CHARACTERIZATION OF AVENACINASE FROM GAEUMANNOMYCES-GRAMINIS VAR AVENAE

The tritici variety of the take-all fungus Gaeumannomyces graminis causes disease on wheat but is unable to attack oats, while the avenae variety can attack both wheat and oats. The resistance of oats to G. graminis var. tritici has been attributed to the presence of a pre-formed inhibitor, avenacin. G. graminis var. avenae isolates are reported to produce an enzyme (avenacinase) which specifically deglucosylates avenacin to less toxic forms. We have verified previous observations that G. graminis var. avenae isolates are more resistant to avenacin than G. graminis var. tritici in agar tests. In addition, culture filtrates of isolates of G. graminis var. avenae have at least 100 times more avenacinase activity than those of isolates of G. graminis var. tritici. The avenacinase activity of a G. graminis var. avenae isolate was characterized as a single extracellular protein species of molecular weight 110 kD, by SDS polyacrylamide gel electrophoresis. © 1991 Academic Press Limited.