Diplodiatoxin, chaetoglobosins, and diplonine associated with a field outbreak of Stenocarpella ear rot in Illinois
Stenocarpella maydis causes a fungal dry-rot of maize ears and is associated with diplodiosis, a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. There have been no reports of Stenocarpella metabolites in maize crop residues. Chemical investigations of S. maydis-infected grain from ears exhibiting different levels of ear rot severity following a 2010 field outbreak of Stenocarpella ear rot in Illinois led to the detection of diplodiatoxin and chaetoglobosins M and O as major components in the ethyl acetate extracts by LC-MS. Following post-harvest moist incubation of the S. maydis-infected grain, the amounts of each compound increased (approx. tenfold) and chaetoglobosin K was detected as a dominant toxin. In separate 1H NMR-based analyses, the neurotoxin diplonine was detected as a minor component in methanol extracts of S. maydis-infected grain as well as cultures of S. maydis isolates from Midwest corn. Proline betaine (=stachydrine) and glycine betaine were also detected in these extracts as major components. This constitutes the first report of chaetoglobosin M, chaetoglobosin O, proline betaine, or glycine betaine from S. maydis, and the first record of diplodiatoxin, diplonine, proline betaine, glycine betaine, or chaetoglobosins M, O, or K being associated with a natural field outreak of S. maydis ear rot.
KeywordsChaetoglobosins Diplodiosis Diplodiatoxin Diplonine Neuromycotoxicosis Proline betaine (Stachydrine) Stenocarpella maydis Zea mays
Support for this work from the National Science Foundation (CHE1011847) is gratefully acknowledged. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the United States Department of Agriculture or the National Science Foundation. USDA is an equal opportunity provider and employer.
Conflict of interest
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