Seed Lipoxygenase Products Modulate Aspergillus Mycotoxin Biosynthesis

• Published in: Molecular plant-microbe interactions Vol. 10; no. 3; pp. 380 - 387
• Main Authors: Burow, G. B., Nesbitt, T. C., Dunlap, J., Keller, N. P.
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.04.1997; The American Phytopathological Society
• Subjects: 13S-hydroperoxy linolenic acid; aflatoxin B1; Aspergillus nidulans; Aspergillus parasiticus; Biological and medical sciences; biosynthesis; defense mechanisms; enzyme activity; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; gene expression; genes; Glycine max; jasmonic acid; linoleate 13S-lipoxygenase; linoleic acid; messenger RNA; methyl jasmonate; mRNA accumulation; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection; plant-microbe interactions; seeds; stcU; sterigmatocystin; Terpenoid; Seeds; Enzyme; Metabolite; Mycotoxin; Host agent relation; Repression; Gene expression; Biological activity; Oil plant(vegetal); Fungi; Resistance; Aspergillus; Regulation(control); Sterigmatocystin; Fungi Imperfecti; Oxidoreductases; Lipoxygenase; Biological contamination; Aflatoxin; Thallophyta
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI.1997.10.3.380

Oilseed crops are frequently subject to contamination by mycotoxins produced by Aspergillus spp., particularly aflatoxin (AF) and to a lesser extent sterigmatocystin (ST). Several studies have suggested that metabolites generated from the plant lipoxygenase (LOX) pathway may either decrease or increase mycotoxin production by Aspergillus spp. We tested the possibility that the occurrence of seed LOX isozymes that produce distinct hydroperoxy fatty acids may account for these different effects on AF biosynthesis. For example, soybean LOX1 catalyzes the addition of O 2 to the C13 position of linoleic and linolenic acids while maize embryo LOX catalyzes the addition of O 2 to the C9 position. In vitro experiments showed that 13S-hydroperoxy fatty acids at concentrations of 10 and 100 μM repressed AF and ST pathway gene expression and significantly (P = 0.05) reduced AF and ST production in both A. parasiticus (AF producer) and A. nidulans (ST producer). Treatment with 1 μM 13S-hydroperoxy linoleic acid also significantly decreased AF production when introduced into growth media at continuous 24-h intervals. In contrast, the same concentrations of 9S-hydroperoxy linoleic acid did not reduce AF or ST production but extended the length of time AF and ST transcripts were detectable. These results show that 13S-hydroperoxy fatty acids directly or indirectly repress AF and ST biosynthesis and provide in vitro evidence that specific seed lipoxygenase activity could provide resistance to mycotoxin contamination by Aspergillus spp.