Frontiers in fungal biology最新文献

Introduction: The Food and Agricultural Organization (FAO) reported that numerous diseases can be traced back to the consumption of unsafe food contaminated with mycotoxins. Mycotoxins are secondary metabolites produced by toxigenic filamentous fungi. Mycotoxins reported to be of socio-economic concerns include aflatoxins, fumonisins, zearalenone, ochratoxin A, and deoxynivalenol. These mycotoxins are frequent contaminants of maize especially in the face of climate change and global food insecurity. South Africa is a leading exporter of maize in Africa, hence, it is crucial to evaluate exposure risks with respect to mycotoxin contamination of maize for consumers' safety.

Materials and method: In total, 752 post-harvest maize samples collected from silos over a 3-year period were analysed using liquid chromatography with tandem mass spectrometry (LC-MS/MS) for the occurrence of mycotoxins.

Results and discussion: The overall mean values for all the quantified mycotoxins were within the South Africa regulatory limit as well as the individual samples, apart from DON and FB mycotoxins with 5% and 1% samples, respectively, above the limit. Citrinin was quantified in South African commercial maize for the first time. The presence of major mycotoxins in South African commercial maize even within safety limits is of public health concern, hence, continuous monitoring and evaluation is recommended.

The filamentous fungus Stachybotrys chartarum is rich in meroterpenoid secondary metabolites, some of which carry o-dialdehyde moieties, which are readily derivatized to isoindolinones by addition of primary amines. The structural diversity of phenylspirodrimanes, in particular, is linked to a wide range of biological activities, making them ideal candidates for semi-synthetic modification. In this study, acetoxystachybotrydial acetate was reacted with l-tryptophan and tryptamine, resulting in the detection of both regiospecific isomeric structures - a rare and significant finding that enabled the examination of four novel reaction products. Besides their successful purification, a detailed report on their isomer-specific behavior with regard to chromatographic retention, UV-spectral specificities, nuclear magnetic resonances, and mass spectrometric fragmentation is given. Furthermore, a comprehensive insight into each compounds' unique effect within the tested biological assays is provided, which include cytotoxicity, genotoxicity, their biological activity against serine proteases of the blood coagulation cascade, and in vitro hepatic metabolism, always in comparison to the non-derivatized substance. Ultimately, each isomer can be distinguished already during the purification process, which extends to the biological assays where we present one less cytotoxic, faster metabolized, and more active regio-isomeric phenylspirodrimane-derivative.

The application of microorganisms as bio-control agents against arthropod populations is a need in many countries, especially in tropical, subtropical, and neotropical endemic areas. Several arthropod species became agricultural pests of paramount economic significance, and many methods have been developed for field and urban applications to prevent their, the most common being the application of chemical insecticides. However, the indiscriminate treatment based upon those substances acted as a selective pressure for upcoming resistant phenotype populations. As alternative tools, microorganisms have been prospected as complementary tools for pest and vectorial control, once they act in a more specific pattern against target organisms than chemicals. They are considered environmentally friendly since they have considerably less off-target effects. Entomopathogenic fungi are organisms capable of exerting pathogenesis in many vector species, thus becoming potential tools for biological management. The entomopathogenic fungi Metarhizium sp. have been investigated as a microbiological agent for the control of populations of insects in tropical regions. However, the development of entomopathogenic fungi as control tools depends on physiological studies regarding aspects such as mechanisms of pathogenicity, secreted enzymes, viability, and host-pathogen aspects. The following review briefly narrates current aspects of entomopathogenic fungi, such as physiology, cellular characteristics, host-pathogen interactions, and its previous applications against different insect orders with medical and economic importance. Approaches integrating new isolation, prospection, characterization, delivery strategies, formulations, and molecular and genetic tools will be decisive to elucidate the molecular mechanisms of EPFs and to develop more sustainable alternative pesticides.

[This corrects the article DOI: 10.3389/ffunb.2024.1451455.].

The complex and dynamic interactions between fungi and plants constitute a critical arena in ecological science. In this comprehensive review paper, we explore the multifaceted relationships at the fungi-plant interface, encompassing both mutualistic and antagonistic interactions, and the environmental factors influencing these associations. Mutualistic associations, notably mycorrhizal relationships, play a pivotal role in enhancing plant health and ecological balance. On the contrary, fungal diseases pose a significant threat to plant health, agriculture, and natural ecosystems, such as rusts, smuts, powdery mildews, downy mildews, and wilts, which can cause extensive damage and lead to substantial economic losses. Environmental constraints encompassing abiotic and biotic factors are elucidated to understand their role in shaping the fungi-plant interface. Temperature, moisture, and soil conditions, along with the presence of other microbes, herbivores, and competing plants, significantly influence the outcome of these interactions. The interplay between mutualism and antagonism is emphasised as a key determinant of ecosystem health and stability. The implications of these interactions extend to overall ecosystem productivity, agriculture, and conservation efforts. The potential applications of this knowledge in bioremediation, biotechnology, and biocontrol strategies emphasise the importance of adapting to climate change. However, challenges and future directions in this field include the impacts of climate change, emerging fungal pathogens, genomic insights, and the role of the fungi-plant interface in restoration ecology. Hence, this review paper provides a comprehensive overview of fungi-plant interactions, their environmental influences, and their applications in agriculture, conservation, and ecological restoration.

Southwest Spain's Río Tinto is a stressful acidic microbial habitat with a noticeably high concentration of toxic heavy metals. Nevertheless, it has an unexpected degree of eukaryotic diversity in its basin, with a high diversity of fungal saprotrophs. Although some studies on the eukaryotic diversity in Rio Tinto have been published, none of them used molecular methodologies to describe the fungal diversity and taxonomic affiliations that emerge along the river in different seasons. The aim of the present study was to isolate and describe the seasonal diversity of the fungal community in the Río Tinto basin and its correlation with the physicochemical parameters existing along the river's course. The taxonomic affiliation of 359 fungal isolates, based on the complete internal transcribed spacer DNA sequences, revealed a high degree of diversity, identifying species belonging primarily to the phylum Ascomycota, but representatives of the Basidiomycota and Mucoromycota phyla were also present. In total, 40 representative isolates along the river were evaluated for their tolerance to toxic heavy metals. Some of the isolates were able to grow in the presence of 1000 mM of Cu²⁺, 750 mM of As⁵⁺ and Cd²⁺, and 100 mM of Co²⁺, Ni²⁺, and Pb²⁺.

Colletotrichum lindemuthianum is the etiological agent of anthracnose disease in common bean (Phaseolus vulgaris L.), noted for its ability to cause serious damage and significant pathogenic variability. This study reveals the features of the high-quality genome of C. lindemuthianum. Analysis showed improvements over the first assembly, with the refined genome having 119 scaffolds, ten times fewer than the first, and a 19% increase in gene number. The effector candidates increased by nearly 1.5 times. More than 40% of the amino acid sequences with homologs in the Pathogen-Host Interactions (PHI-base) database are linked to pathogenicity. Of 18 putative proteins identified as Chitinase-like Protein, six have a mutation in the enzyme catalytic motif, and three showed gene expression in the biotrophic phase, indicating they can act as effectors. Comparative genomic analyses with 30 other fungal species revealed that C. lindemuthianum is among the top three fungi encoding transport proteins. Seven Necrosis and Ethylene-Inducing Peptide 1 (Nep1)-Like Proteins (NLPs) are present in the C. lindemuthianum genome, but none had complete identity with the GHRHDWE conserved motif of NLPs; two were grouped with proteins that induce necrosis and may retain the capability to induce host necrosis. Colletotrichum species show a high number of secondary metabolite (SM) clusters, with C. lindemuthianum having 47 SM clusters. Approximately 60% of the C. lindemuthianum genome is composed of repetitive elements, a significantly higher proportion than in other fungi. These differences in transposable element (TE) numbers may explain why C. lindemuthianum has one of the largest genomes among the fungi analyzed. A significant portion of its genome comprises retroelements, particularly the Ty1/Copia superfamily, which accounts for 22% of the genome and represents 40% of the repetitive elements. The genomic profile features a remarkably high RIP-affected genomic proportion of 54.77%, indicating substantial RIP activity within this species. This high-quality genome of C. lindemuthianum, a significant pathogen in common bean cultivation, will support future research into this pathosystem, fostering a deeper understanding of the interaction between the fungus and its host.

Understanding the interactions between fungal plant pathogens and host roots is crucial for developing effective disease management strategies. This study investigates the molecular mechanisms underpinning the chemotropic responses of the maize anthracnose fungus Colletotrichum graminicola to maize root exudates. Combining the generation of a deletion mutant with monitoring of disease symptom development and detailed analysis of chemotropic growth using a 3D-printed device, we identify the 7-transmembrane G-protein coupled receptor (GPCR) CgSte3 as a key player in sensing both plant-derived class III peroxidases and diterpenoids. Activation of CgSte3 initiates signaling through CgSo, a homolog to the Cell Wall Integrity Mitogen-Activated Protein Kinase (CWI MAPK) pathway scaffold protein identified in other filamentous fungi, facilitating the pathogen's growth towards plant defense molecules. The NADPH oxidase CgNox2 is crucial for peroxidase sensing but not for diterpenoid detection. These findings reveal that CgSte3 and CWI MAPK pathways are central to C. graminicola's ability to hijack plant defense signals, highlighting potential targets for controlling maize anthracnose.

Olive tree anthracnose is caused by infection with Colletotrichum fungi, which in Portugal are mostly C. nymphaeae, C. godetiae, and C. gloeosporioides s.s. Severe economic losses are caused by this disease that would benefit from a greener and more efficient alternative to the present agrochemical methods. Yeasts are serious candidates for pre-harvest/in field biocontrol of fungal infections. This work identified the yeast Wickerhamomyces anomalus as a strong antagonizer of the three fungi and studied in vitro this ability and its associated mechanisms. Antagonism was shown to not depend on the secretion of volatile compounds (VOCs), or siderophores or any other agar-diffusible compound, including hydrolytic enzymes. Rather, it occurred mostly in a cell-to-cell contact dependent manner. This was devised through detailed microscopic assessment of yeast-fungus cocultures. This showed that W. anomalus antagonism of the three Colletotrichum proceeded through (i) the adhesion of yeast cells to the phytopathogen hyphae, (ii) the secretion of a viscous extracellular matrix, and (iii) the emptying of the hyphae. Yeasts ultimately putatively feed on hyphal contents, which is supported by light microscopy observation of MB and PI co-culture-stained samples. Accordingly, numerous W. anomalus cells were observed packing inside C. godetiae emptied hyphae. This behaviour can be considered microbial predation and classified as necrotrophic mycoparasitism, more explicitly in the case of C. godetiae. The results support the prospect of future application of W. anomalus as a living biofungicide/BCA in the preharvest control of olive anthracnose.