New Antifungal Agents from Lignocellulose Hydrolysate
A rise in resistance to current antifungals necessitates strategies to identify alternative sources of effective fungicides to protect bioenergy crops. Scientists at the Department of Energy’s Great Lakes Bioenergy Research Center discovered that poacic acid found in lignocellulosic hydrolysates of grasses functions as a potent antifungal compound. Several lines of evidence pointed toward fungal cell wall synthesis as the point of action of poacic acid. Chemical genomics using Saccharomyces cerevisiae showed that loss of cell wall synthesis and maintenance genes conferred increased sensitivity to poacic acid. In addition, morphological analysis of cells treated with poacic acid revealed morphologies similar to cells treated with other cell wall-targeting drugs and mutants with deletions in genes involved in processes related to cell wall biogenesis. Through its activity on the glucan layer, poacic acid inhibits growth of the fungi Sclerotinia sclerotiorum and Alternaria solani as well as the oomycete Phytophthora sojae. A single application of poacic acid to leaves infected with the broad-range fungal pathogen S. sclerotiorum substantially reduced lesion development on soybean leaves. The discovery of poacic acid as a natural antifungal agent targeting ß-1,3-glucan further clarifies the nature and mechanism of fermentation inhibitors found in lignocellulosic hydrolysates. This research highlights the potential use of products generated in the processing of renewable biomass toward biofuels as a source of valuable bioactive compounds.
Piotrowski, J. S., H. Okada, F. Lu, S. C. Li, L. Hinchman, A. Ranjan, D. L. Smith, A. J. Higbee, A. Ulbrich, J. J. Coon, R. Deshpande, Y. V. Bukhman, S. McIlwain, I. M. Ong, C. L. Myers, C. Boone, R. Landick, J. Ralph, M. Kabbage, and Y. Ohya. 2015. “Plant-Derived Antifungal Agent Poacic Acid Targets ß-1,3-Glucan,” Proceedings of the National Academy of Sciences (USA), DOI: 10.1073/pnas.1410400112.