Oxylipins act as determinants of natural product biosynthesis and seed colonization in Aspergillus nidulans

Authors

  • Dimitrios I. Tsitsigiannis,

    1. Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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    • Present address: The Sainsbury Laboratory, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK.

  • Nancy P. Keller

    Corresponding author
    1. Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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*E-mail npk@plantpath.wisc.edu; Tel. (+1) 608 262 9795; Fax (+1) 606 263 2626.

Summary

Secreted, hormone-like lipogenic molecules, called oxylipins, mediate the balance of asexual to sexual spore ratio in Aspergillus nidulans. Oxylipin production in this fungus is dependent on developmental regulation of three conserved fatty acid oxygenases, PpoA, PpoB and PpoC. Here, we show that in addition to altering spore ratios, loss of ppo genes affect natural product biosynthesis and seed colonization. ΔppoA;ΔppoC and ΔppoA;ΔppoB;ΔppoC mutants were unable to produce the mycotoxin sterigmatocystin (ST) in vitro or in planta but in contrast overproduced the antibiotic penicillin (PN). These findings were correlated with decreased expression of genes involved in ST biosynthesis and increased expression of a PN biosynthetic gene, thus suggesting that oxylipin species regulate secondary metabolites at the transcriptional level. Additionally, the ΔppoA;ΔppoC and the ΔppoA;ΔppoB;ΔppoC mutants were defective in colonization of peanut seeds as reflected by a decrease in conidiation and production of the seed degradative enzyme lipase. These results indicate that oxylipin production is important for host colonization and mycotoxin production and may provide a promising target for future control strategies.

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