Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/1998
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Pathogenic strains of the milo disease pathogen, Periconia circinata, produce peritoxins, low mol wt, chlorinated peptides with specific toxicity against susceptible sorghum genotypes. Putative intermediates in the biosynthetic pathway were characterized by LC-MS of culture fluids from toxin-producing (TOX+) and non-producing (tox-) strains. The earliest intermediates in the pathway were identified as N-3-(pentenyl)-glutaroyl-aspartate and circinatin, which accumulated during log phase of growth and became chlorinated prior to cyclization of the pentenyl-glutaroyl moiety. None of the intermediates were detected in tox- strains. Degenerate primers corresponding to conserved sequences of peptide synthetases were used to clone a homolog from TOX+. With this clone as a probe in Southern analyses, polymorphisms were evident between TOX+ and tox- strains. The results suggested that both strains contained the same copy of the gene, but TOX+ strains contained an additional analog. Gene knock-out experiments will be used to determine the essentiality of this gene for peritoxin synthesis.