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.
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
Sugarcane is an important sugar crop, and smut disease caused by Sporisorium scitamineum poses a severe threat with limited control measures. This study is based on transcriptome sequencing data from two distinct pathogenic strains of Sporisorium scitamineum generated in our laboratory. Among the significantly differentially expressed genes, we identified a gene predicted to encode a monocarboxylate permease, which we designated SsMP1. To investigate its biological function, SsMP1 knockout and complemented mutants were generated using PEG-mediated protoplast transformation. Our results showed that SsMP1 had little to no effect on sporidial morphology, colony morphology, growth rate, or tolerance to abiotic stresses. In the knockout mutant, SsMP1 expression was undetectable, whereas it was readily detected in both the wild-type and complemented strains, Moreover, the expression level in the complemented mutant was restored to that of the wild-type strain. Notably, sexual mating ability was almost completely abolished in the knockout mutant but was fully restored in the complemented mutant. Interestingly, supplementation with exogenous signaling molecules, including cAMP or tryptophol, largely rescued the mating defect of the knockout mutant. Consistently, the expression levels of Uac1, a gene involved in cAMP biosynthesis, and Aro8, a gene associated with tryptophol biosynthesis, were significantly lower in the knockout mutant than in the wild-type and complemented strains. In addition, the knockout mutant exhibited more than a 70% reduction in pathogenicity compared with the wild-type and complemented strains. Furthermore, citric acid transport and uptake were markedly impaired in the knockout mutant. Taken together, these findings suggest that SsMP1 may indirectly regulate the expression of key genes involved in the cAMP and tryptophol biosynthetic pathways, thereby modulating signaling molecule production and subsequently affecting mating and pathogenicity. In addition, SsMP1 appears to positively regulate citric acid uptake and transport in haploid sporidia. This study provides new molecular insights into the pathogenic mechanisms of S. scitamineum.
Sisi Zhou, Yi Zhang, Jiali Zhou et al.· Frontiers in Microbiology· 2 citations
It is shown that the understudied bZIP transcription factor PnAda1 is an important downstream component of this PnPf2-regulatory network, and current understanding of the transcriptional network underlying virulence, metabolism and stress adaptation in an important fungal wheat pathogen is expanded.
S. Morikawa, Leon Lenzo, Keshara Colomba Thanthrige et al.· bioRxiv· 0 citations
It is shown that the hyphae of the filamentous fungus Trichoderma guizhouense can differentiate into typical terminal and intercalary chlamydospores characterized by double-layered spherical or ellipsoidal cell walls with accumulated lipid bodies and nuclei, indicating the entry of cells into dormancy.
Yiting Hou, Yifan Li, Cheng Chen et al.· Applied and Environmental Mi...· 0 citations
Insight is provided into the regulatory roles of PP2A regulatory subunit SsRts1 in S. scitamineum, and the understanding of PP2A function in plant-pathogenic fungi is expanded.
Jinfeng Qiu, Haoming Wu, Ying Liu et al.· Virulence· 0 citations