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Poster: Molecular & Cellular Plant-Microbe Interactions: Proteomics/Metabolomics/Genomics


Analysis of a ketide synthase from fungal endophytes of toxic locoweeds
A. NOOR (1), D. Baucom (2), D. Cook (3), R. Creamer (2) (1) Molecular Biology, New Mexico State University, U.S.A.; (2) New Mexico State University, U.S.A.; (3) USDA, ARS, U.S.A.; (4) New Mexico State University, U.S.A.

Toxic Astragalus and Oxtropis locoweeds are legumes in which toxicity is due to fungal endophytes of Alternaria section Undifilum sp. (A. sec. U. sp.). The fungi produce swainsonine, an alkaloid α-mannosidse inhibitor that causes locosim disease when consumed by grazing animals. Polyketide synthase (PKSs) is a key enzyme in swainsonine biosynthesis. KS is the most highly conserved and informative of the multi-domain enzymes for predicting pathway associations. The objective of this study was to analyze the KS sequences from A. sec. U. sp. isolated from locoweed plants of Astragalus lentiginosus var. diphysus, lentiginosus, araneosus, and wahweapensis, and A. mollissimus var. biglovii, earleii, wootoni and mollissimus that were collected from the western USA. The KS from these endophytic fungi were compared to A. sec. U. oxytropis isolated from Oxytropis lamberteii and O. sericea using PCR. A 741 bp amplicon was sequenced and analyzed to produce maximum parsimony trees. Fungi isolated from different varieties of locoweed and locations had different morphologies and colors in culture. The KS sequences were highly conserved across A. sec. U. sp., but differed slightly between A. sec. U. oxytropis and A. sec. U. fulvum and A. sec. U. cinereum. Comparing the KS from additional locoweed endophytes and A. sec. U. sp. will allow the further examination of phylogenetic relationships among these fungi.