The Arf-GAP Proteins AoGcs1 and AoGts1 Regulate Mycelial Development, Endocytosis, and Pathogenicity in Arthrobotrys oligospora

Abstract

Small GTPases from the ADP-ribosylation factor (Arf) family and their activating proteins (Arf-GAPs) regulate mycelial development, endocytosis, and virulence in fungi. Here, we identified two orthologous Arf-GAP proteins, AoGcs1 and AoGts1, in a typical nematode-trapping fungus Arthrobotrys oligospora. The transcription of Aogcs1 and Aogts1 was highly expressed in the sporulation stage. The deletion of Aogcs1 and Aogts1 caused defects in DNA damage, endocytosis, scavenging of reactive oxygen species, lipid droplet storage, mitochondrial activity, autophagy, serine protease activity, and the response to endoplasmic reticulum stress. The combined effects resulted in slow growth, decreased sporulation capacity, increased susceptibility to chemical stressors and heat shock, and decreased pathogenicity of the mutants compared with the wild-type (WT) strain. Although deletion of Aogcs1 and Aogts1 produced similar phenotfypic traits, their roles varied in conidiation and proteolytic activity. The ΔAogts1 mutant showed a remarkable reduction in conidial yield compared with the WT strain but not in proteolytic activity; in contrast, the ΔAogcs1 mutant showed an increase in proteolytic activity but not in sporulation. In addition, the growth of ΔAogcs1 and ΔAogts1 mutants was promoted by rapamycin, and the ΔAogts1 mutant was sensitive to H-89. Collectively, the ΔAogts1 mutant showed a more remarkable difference compared with the WT strain than the ΔAogcs1 mutant. Our study further illustrates the importance of Arf-GAPs in the growth, development, and pathogenicity of nematode-trapping fungi.

AoSte12 Is Required for Mycelial Development, Conidiation, Trap Morphogenesis, and Secondary Metabolism by Regulating Hyphal Fusion in Nematode-Trapping Fungus Arthrobotrys oligospora

“…Moreover, several genes associated with lipids, actin, growth, the MAPK pathway, vesicles, cell fusion, and TCA cycles were significantly enriched and consistent with phenotypic traits. For example, G protein complex alpha subunit and cell division control protein Cdc42 have been proven to play a crucial role in mycelial growth, conidiation, trap formation, and stress response in A. oligospora ( 11 , 49 ). Meanwhile, Ssk2 and Ste50 are indispensable components of the MAPK signaling cascade and have been reported to be involved in growth, conidiation, stress response, and virulence in A. oligospora and other pathogenic fungi ( 32 , 50 ).…”

ESCRT pathway-dependent MVBs contribute to the morphogenesis of the fungusArthrobotrys oligospora

“…The investigation of trap regulation will lead to comprehensive understandings of how cell types transform and why NT fungi have co-evolved with the emergence of nematodes. Over the past decade, G-protein-associated signaling has been considered the main explanation underlying the trap formation [23, 41, 42]. Multi-omics analysis commonly revealed that the membrane biogenesis-associated pathways contribute to trap formation [43].…”

Peroxin Pex14/17 Is Required for Trap Formation, and Plays Pleiotropic Roles in Mycelial Development, Stress Response, and Secondary Metabolism in Arthrobotrys oligospora

“…Cellular ROS accumulation in the fungal hyphae was determined by dihydroethidium (DHE) (Beyotime, Shanghai, China) staining. Briefly, the collected mycelia were mixed with 10 μg/mL DHE solution, incubated at 37°C for 30 min, and then washed with phosphate-buffered saline (PBS) twice ( 62 ). Subsequently, ROS levels were estimated from the intensity of DHE fluorescence with the same weight of mycelium via multimode microplate reader (Molecular Devices, Shanghai, China).…”