Arthrobotrys oligospora is a widely distributed nematode-trapping (NT) fungus that captures nematodes by developing flexible traps. In fungi, protein tyrosine phosphatases (PTPs) are crucial for intracellular signaling, governing processes such as cell growth, proliferation, and differentiation in filamentous species. In this study, we characterized the functions of AoPtp (an orthologous PTP) through gene knockout, phenotypic, multi-omics, and yeast two-hybrid (Y2H) analyses. Inactivation of Aoptp caused a marked increase in trap number and nematode predation ability. The ΔAoptp mutants exhibited enhanced mycelial growth on TYGA and TG media, but showed no significant growth difference on PDA medium, together with reduced spore yield, and altered stress responses. In addition, phenotypic and transcriptomic analyses suggested that AoPtp is associated with lipid droplet accumulation and autophagy-related processes. Metabolomic analysis revealed extensive changes in metabolic profiles, including an approximately six-fold reduction in arthrobotrisin abundance. Furthermore, AoPtp interacts with AoFus3 and AoSlt2 in a Y2H assay, suggesting its potential involvement in the mitogen-activated protein kinase signaling pathway. In summary, we demonstrated that AoPtp is a pleiotropic regulator of sporulation, trap development, stress tolerance, and metabolic process in A. oligospora. These findings provide a basis for probing the regulatory mechanism of PTPs underlying trap formation in NT fungi, as well as for exploring their potential applications in biocontrol of nematode-associated diseases.
Guiqiu Luo, Lirong Zhu, Hui Yuan et al.· Journal of Fungi· 0 citations
Sporulation is essential for asexual reproduction and dispersal in filamentous fungi, but the roles of upstream sporulation regulators in nematode-trapping (NT) fungi remain poorly understood. In this study, we characterized two Flb homologs, AoFlbB and AoFlbD, in Arthrobotrys oligospora. AoFlbB contains a bZIP-type domain, whereas AoFlbD contains a Myb-like DNA-binding domain, and both proteins are conserved among NT fungi. Deleting AoflbB or AoflbD had little effect on hyphal growth but markedly reduced spore production and altered spore germination, and real-time quantitative PCR analysis showed that the central sporulation regulators were significantly differently expressed, collectively indicating that AoFlbB and AoFlbD play positive roles in sporulation. Furthermore, both mutants produced more traps and showed enhanced nematode predation efficiency. The mutants also showed altered cell wall stress responses, hyphal cell length, nuclear number, endocytic trafficking, and metabolite profiles. The ΔAoflbB mutant showed irregular cell wall wrinkling, whereas the ΔAoflbD mutant displayed increased vesicle-like structures and accelerated FM4-64 uptake. Extracellular protease activity was comparable to the WT in ΔAoflbB but reduced in ΔAoflbD. Transcriptomic analysis of ΔAoflbD showed that the differentially expressed genes were significantly enriched in metabolism-related pathways. These findings indicate that AoFlbB and AoFlbD promote sporulation and contribute to the coordination of asexual reproduction and trap formation in A. oligospora.
Yi Chen, Yanmei Shen, Hui Yuan et al.· Microorganisms· 0 citations