title: Differential synthesis of peritoxins and precursors by pathogenic strains of the fungus Periconia circinata.
abstract: Pathogenic strains of the soilborne fungus Periconia circinata produce peritoxins with host-selective toxicity against susceptible genotypes of sorghum. The peritoxins are low-molecular-weight, hybrid molecules consisting of a peptide and a chlorinated polyketide. Culture fluids from pathogenic, toxin-producing (Tox(+)) and nonpathogenic, non-toxin-producing (Tox(-)) strains were analyzed directly by gradient high-performance liquid chromatography (HPLC) with photodiode array detection and HPLC-mass spectrometry to detect intermediates and final products of the biosynthetic pathway. This approach allowed us to compare the metabolite profiles of Tox(+) and Tox(-) strains. Peritoxins A and B and the biologically inactive intermediates, N-3-(E-pentenyl)-glutaroyl-aspartate, circinatin, and 7-chlorocircinatin, were detected only in culture fluids of the Tox(+) strains. The latter two compounds were produced consistently by Tox(+) strains regardless of the amount of peritoxins produced under various culture conditions. In summary, none of the known peritoxin-related metabolites were detected in Tox(-) strains, which suggests that these strains may lack one or more functional genes required for peritoxin biosynthesis.
authors.affiliation: Boyce Thompson Institute, Cornell University, Ithaca, New York 14853-1801, USA. acc7@cornell.edu
authors.forename: A C
authors.initials: AC
authors.lastname: Churchill
authors.forename: L D
authors.initials: LD
authors.lastname: Dunkle
authors.forename: W
authors.initials: W
authors.lastname: Silbert
authors.forename: K J
authors.initials: KJ
authors.lastname: Kennedy
authors.forename: V
authors.initials: V
authors.lastname: Macko
mesh_terms: D001203:Ascomycota / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity*; D002851:Chromatography, High Pressure Liquid; D003521:Cyclopropanes; D002523:Edible Grain / Q000382:microbiology; D009183:Mycotoxins / Q000096:biosynthesis*; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000096:biosynthesis; D011498:Protein Precursors / Q000096:biosynthesis*
chemical_list: D003521:Cyclopropanes; D009183:Mycotoxins; D010940:Plant Proteins; D011498:Protein Precursors; C077344:peritoxin B; C077343:peritoxin A