Cellular communication and fusion regulates cell fusion, trap morphogenesis, conidiation, and secondary metabolism in Arthrobotrys oligospora

In this study, we characterized Aoadv-1, Aoso, Aoham-6, and Aoham-5 of A. oligospora, homologous to those involved in cellular communication and fusion in the model fungus Neurospora crassa. The deletion of four genes resulted in the complete loss of cell fusion, and traps produced by mutants do not close to form mycelial rings but are still capable of capturing nematodes. Meanwhile, the absence of these genes inhibited aerial mycelial extension, slowed colony growth, and increased mycelial branching. In addition, the mutants showed reduced sporulation capacity, reduced tolerance to oxidative stress, increased sensitivity to SDS, and altered lipid droplet accumulation and autophagy. Furthermore, transcriptome analysis revealed that Aoadv-1 and Aoso were involved in plasma membrane fusion, transmembrane transport of multiple nutrients, signal transduction, response to oxidative stress, cell wall, lipid metabolism, and autophagy. In addition, metabolomic analysis showed that Aoadv-1 and Aoso were involved in biosynthesis of secondary metabolites. Our results revealed that Aoadv-1, Aoso, Aoham-6, and Aoham-5 regulate mycelial growth and trap morphogenesis through cell fusion, which provides a valuable reference for the molecular mechanisms of cellular communication regulating the mycelia development and trap morphogenesis in NT fungi. The WT,ΔAoadv-1, and ΔAoso mutant strains, were cultured in PDA medium at 28 °C, 180 rpm for 3 days, and mycelium was collected. The mycelium was divided and induced with about 400 nematodes for 0 and 36 h, respectively. Three replicates were performed for each sample.