Forward genetic screens identified mutants with defects in trap morphogenesis in the nematode-trapping fungus Arthrobotrys oligospora

Abstract

Nematode-trapping fungi (NTF) are carnivorous fungi that prey on nematodes under nutrient-poor conditions via specialized hyphae that function as traps. The molecular mechanisms involved in the interactions between nematode-trapping fungi and their nematode prey are largely unknown. In this study, we conducted forward genetic screens to identify potential genes and pathways that are involved in trap morphogenesis and predation in the NTF Arthrobotrys oligospora. Using Ethyl methanesulfonate and UV as the mutagens, we generated 5552 randomly-mutagenized A. oligospora strains and identified 15 mutants with strong defects in trap morphogenesis. Whole genome sequencing and bioinformatic analyses revealed mutations in genes with roles in signaling, transcription or membrane transport that may contribute to the defects of trap morphogenesis in these mutants. We further conducted functional analyses on a candidate gene, YBP-1, and demonstrate that mutation of that gene was causative of the phenotypes observed in one of the mutants. The methods established in this study might provide helpful insights for establishing forward genetic screening methods for other non-model fungal species.

The STRIPAK component SipC is involved in morphology and cell-fate determination in the nematode-trapping fungus Duddingtonia flagrans

“…Recently, a random mutagenesis analysis identified 15 mutants with deficiencies in trap morphogenesis. However, there are still difficulties in gene mapping because of heterokaryotic transformants and the lack of genetic crosses of NTF (Huang et al 2021). In D. flagrans, it was shown that a cell dialog between the tip trap cell and the basal cell is required for ring closure (Youssar et al 2019).…”