Novel Polyketide-Terpenoid Hybrid Metabolites and Increased Fungal Nematocidal Ability by Disruption of Genes <i>277</i> and <i>279</i> in Nematode-Trapping Fungus <i>Arthrobotrys oligospora</i>

Abstract

Nematode-trapping fungus <i>Arthrobotrys oligospora</i> can produce a type of sesquiterpenyl epoxy-cyclohexenoid (SEC) metabolites that are regarded as characteristic chemtaxonomic markers. Here, we reported investigation on the functions of a putatively cupin-like family gene <i>277</i> and a dehydrogenase gene <i>279</i> by gene engineering, chemical metabolite profiling and phenotype analysis. Ten targeted metabolites were isolated from two mutants Δ<i>277</i> and Δ<i>279</i> and four novel metabolites including three polyketide-terpenoid (PK-TP) hybrid ones were characterized. Metabolite <b>C</b>_<b>277-1</b> from mutant Δ<i>277</i> shared the characteristic feature of the first and simplest PK-TP hybrid precursor, prenyl toluquinol, and metabolites <b>C</b>_<b>279-1</b> and <b>C</b>_<b>279-2</b> from mutant Δ<i>279</i> shared the basic carbon skeleton of the key PK-TP hybrid precursor, farnesyl toluquinol, for biosynthesis of SEC metabolites. These results suggested that gene <i>277</i> should be involved in biosynthesis of the second prenyl unit for farnesyl toluquinol precursor, and gene <i>279</i> might be responsible for the diagnostic epoxy formation. Further analysis revealed that genes <i>277</i> and <i>279</i> might play roles in fungal conidiation, predatory trap formation, and nematode-capturing ability.