9408035 Belanger Fungal endophytes of the genus Acremonium infect many wild and cultivated grass species and these associations have major ecological and agricultural impacts. In many instances the endophyte-grass association is strictly mutualistic. The fungi synthesize alkaloids which protect the plants from herbivory by insects and other herbivores, while the plants supply the fungi with necessary nutrients. The presence of toxic alkaloids in endophyte-infected forage grasses, however, can result in poisoning syndromes in grazing livestock. Because of the importance of livestock toxicosis to agriculture, considerable research has been done on this aspect of endophyte infection of grasses. Dr. Belanger is interested in the physiology of the interaction of the fungal endophytes and their host grasses. In contrast to the information on alkaloids and animal toxicosis, the physiological aspects of endophyte-grass interactions have not been well characterized in any system. The long range objective of this research is to understand the factors which are important in establishing effective symbiotic associations between the Acremonium fungi and their host grasses. Dr. Belanger has detected a novel fungal protease which is expressed in the endophytic infection of the grass species Poa ampla by the fungus Acremonium typhinum. The focus of this proposal is to further characterize this protease and determine its role in the endophyte-grass association. In addition to its potential biological significance, this protease has unusual features which make it a particularly interesting enzyme in its own right. The specific objectives of this research are: 1) Further characterization of the enzymatic and physical properties of the A. typhinum protease 2) Characterization of cDNA and genomic clones for the A. typhinum protease 3) Determination of the effect of protease gene disruption on the ability of the fungus to infect its host grass
