Cell wall signal sensors regulate cell wall integrity, conidiation, trap formation, and secondary metabolism in Arthrobotrys oligospora

Cell wall signal sensors (CWSSs) are pivotal upstream regulators of the cell wall integrity (CWI) signalling pathway; most genes in the CWI pathway are crucial for cell-wall structure and stress responses in filamentous fungi. Nematode-trapping (NT) fungi can undergo a specialised developmental shift from saprophytism to parasitism upon sensing nematode-related environmental signals, while the functions of CWSSs during this process are still largely uncharacterised. In this study, we characterised the roles and potential regulatory networks of four WSC proteins (AoWsc1, AoWsc2, AoWsc3, and AoWsc4) in the NT fungus Arthrobotrys oligospora, revealing their key roles in WSC-mediated cell surface sensing for trap development. The deletion of wsc genes affected cell wall components (chitin and glucan), structure, stress response, sporulation, trap formation, and nematode predation efficiency. Moreover, the four wsc genes are involved in autophagy, endocytosis, multiple metabolic and cellular processes. Our study highlights the crucial roles of the four CWSSs in A. oligospora, providing new insights into how the CWI pathway orchestrates cell wall structure, asexual development, and trap formation in NT fungi.