The Chemistry of Fungal Antagonism and Defense

University Of Iowa, Iowa City IA

Investigators

Abstract

With this award, the Chemical Synthesis Program is renewing support for the work of Professor James B. Gloer of the Department of Chemistry at the University of Iowa. With his collaborators, Patrick F. Dowd and Donald T. Wicklow of the U.S. Department of Agriculture, Professor Gloer is isolating new natural organic compounds from fungi. The project will continue this distinctive research program in fungal natural products chemistry. Primary focus will be placed on chemical studies of mycoparasitic/fungicolous fungi, and on fungal endophytes that occur in cereal crop plants. Mycoparasitic/fungicolous fungi attack and colonize other fungi in nature. Invasion by these colonists often involves antibiosis toward the host, and therefore, such colonists may be valuable, underexplored sources of natural antifungal agents. Results from prior NSF support provide strong evidence for the validity of this hypothesis. Efforts during the proposed grant period will focus on completion of the studies of a collection of nearly 800 diverse fungal colonists obtained from varied microclimates found on the island of Hawaii. A second direction follows from the discovery that isolates of widespread corn endophytes produce natural products of various types that show antagonistic activity against other, competing fungi encountered in corn plants, including important disease-causing and mycotoxin-producing species. Studies of the occurrence and significance of these metabolites will continue, and will be expanded to include fungi from other crop plants (rye, wheat, barley, sorghum), and a limited number of prairie grasses, in search of further metabolites that show similar biological effects and potential significance. In both projects, the search for new chemistry is guided by assays for activity against two important fungal species and/or an agriculturally important insect pest. An assay for Hsp90 activity will also be included based on a discovery in the most recent grant period that a common corn endophyte produces a potent inhibitor of Hsp90 function. Many new bioactive natural products have been discovered through these hypothesis-guided studies, and further success is expected because of the relatively unexplored nature of these fungal groups. Antifungal and antiinsectan agents are of potential practical value to society in agriculture and medicine, and can also be valuable as tools to assist in discovery of new modes of action. Findings from this project are also expected to contribute to fundamental scientific knowledge in other disciplines, including fungal ecology, taxonomy, biodiversity, crop/food science, and evolutionary biology.