The High Osmolarity Glycerol (HOG) Pathway Functions in Osmosensing, Trap Morphogenesis and Conidiation of the Nematode-Trapping Fungus .

Hog1, a mitogen-activated protein kinase (MAPK), has been identified in diverse fungal species, and it regulates various cellular processes, such as osmoadaptation, nutrient-sensing, and pathogenesis. However, the roles that Hog1 plays in nematode-trapping fungi were previously unclear. Here, we characterized orthologs of Hog1 and membrane mucin Msb2 in the nematode-trapping fungus . We generated gene deletion mutants of and in , and characterized their roles in osmosensing, growth, and trap morphogenesis. We found that both and mutants were highly sensitive to high osmolarity. Predation analyses further revealed that and deletion caused a reduction in trap formation and predation efficiency. Furthermore, is required for conidiation in , demonstrating its critical role in this developmental pathway. In summary, this study demonstrated that the conserved Hog1 and Msb2 govern physiology, growth and development in the nematode-trapping fungus .