Acetylation of Sesquiterpenyl Epoxy-Cyclohexenoids Regulates Fungal Growth, Stress Resistance, Endocytosis, and Pathogenicity of Nematode-Trapping Fungus Arthrobotrys oligospora via Metabolism and Transcription

Sesquiterpenyl epoxy-cyclohexenoids
(SECs) that depend on a polyketide
synthase–terpenoid synthase (PKS–TPS) pathway are widely
distributed in plant pathogenic fungi. However, the biosynthesis and
function of the acetylated SECs still remained cryptic. Here, we identified
that AOL_s00215g 273 (273) was responsible
for the acetylation of SECs in Arthrobotrys oligospora via the construction of Δ273, in which the acetylated SECs
were absent and major antibacterial nonacetylated SECs accumulated.
Mutant Δ273 displayed increased trap formation, and nematicidal
and antibacterial activities but decreased fungal growth and soil
colonization. Glutamine, a key precursor for NH3 as a
trap inducer, was highly accumulated, and biologically active phenylpropanoids
and antibiotics were highly enriched in Δ273. The decreased
endocytosis and increased autophagosomes, with the most upregulated
genes involved in maintaining DNA and transcriptional stability and
pathways related to coronavirus disease and exosome, suggested that
lack of 273 might result in increased virus infection and the acetylation
of SECs played a key role in fungal diverse antagonistic ability.