Septin AoCDC11 is involved in trap morphogenesis, conidiation, and vegetative growth in carnivorous Arthrobotrys oligospora.

Septins, a conserved family of cytoskeletal proteins with GTP-binding domains, play key roles in cell polarity, morphogenesis, cytoskeleton organization, and membrane remodeling. The nematode-trapping fungus Arthrobotrys oligospora can capture and kill nematodes using adhesive networks. It has been highlighted the importance of cell polarity, actin organization, and membrane remodeling in the process of trap formation, but the role of septins in adhesive-network forming remains unclear. In this study, we investigated the functions of AoCDC11, an ortholog of Saccharomyces cerevisiae CDC11, through gene disruption and multiphenotypic analysis. Disruption of AoCDC11 led to reduced trap production and abnormal trap morphology. Compared to the wild type, ΔAoCDC11 mutants significantly reduced trap formation to emerge more vegetative hyphae and produced more incompletely fused adhesive networks (45 % vs. 10 %) by fewer trap loops and septa. Additionally, ΔAoCDC11 mutants exhibited a 36 % reduction in hyphal growth and 88 % decrease in conidiation compared to the wild type. Transcriptomic analysis revealed that AoCDC11 regulated genes involved in trap development, including those related to the cell cycle, anatomical structure development, cellular morphogenesis, vesicle transport, and membrane trafficking. These findings suggest that AoCDC11 plays a crucial role in trap morphogenesis, vegetative growth, and conidiation by modulating multiple biological processes. This study expands our understanding of the functions of septins in morphogenesis and survival strategy of nematode-trapping fungi.