PHENYLOXIDASE PRODUCTION BY AND ITS ROLE IN PATHOGENESIS IN LOBLOLLY John Michael Bordeaux and Jeffrey F.D. Dean

Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602

ABSTRACT

The woodwasp noctilio and its symbiotic We have developed and optimized a defined Amylostereum areolatum constitute an medium for culturing A. areolatum in the exotic pathosystem recently introduced into laboratory and are currently establishing growth North America. Capable of killing living, healthy curves for the fungus. Conditions have been trees, S. noctilio has ravaged pine plantations of established to increase dry weight of mycelium, the Southern Hemisphere and poses an immediate as well as increase phenoloxidase enzyme threat to the forests of the United States, production. We have also established a bioassay notably the commercially important loblolly pine system with P. taeda seedlings to demonstrate (Pinus taeda L.) forests of the Southeast. susceptibility to A. areolatum infection. Our investigations have shown that the fungus To more completely investigate the role of involved in the symbiosis, A. areolatum, produces specific phenoloxidases in the disease process, enzymes capable of oxidizing the phenoloxidase we are working to isolate A. areolatum mutants substrates, ABTS, guaiacol, and syringaldazine, that do not express these enzymes. Subsequent in solid media and ABTS in liquid media. The work will focus on characterizing the enzymes responsible enzymes are likely laccases, as well involved, as well as elucidating the specific role as one or more peroxidases. We hypothesize that: played by these enzymes in the disease process. Having a better understanding of the specific 1. Amylostereum areolatum, like many other interactions between individual players in this white-rot fungi, produces laccase. pathosystem will enable us to pursue multiple 2. This laccase is involved in the pathogenicity approaches to subverting key interactions, which of the fungus to loblolly pine. should provide a more powerful approach to tree protection.

2008 USDA Research Forum on Invasive 7