Fungal Biology Reviews最新文献

Environmental conditions are becoming increasingly challenging in managed ecosystems, especially in agricultural fields, where environmentally friendly solutions are urgently needed. Fungal symbionts offer great opportunities to enhance crop production and ecosystem sustainability under environmental stress. Some fungi are relatively well investigated (e.g., arbuscular mycorrhiza) and regularly used in commercial products, while others, such as fungal endophytes, are not well-known in this market, yet. Here, we review I) the characteristics and benefits, II) the advantages and challenges of principal isolation, preservation, inoculation, and field applications methods, and III) the environmental stress resistance mechanisms for different beneficial fungi. Utilization of mycorrhizae is still facing many challenges, particularly in terms of acquiring pure cultures and successfully establishing their symbiosis in the field. Effects of mycorrhizal associations on the above-ground organs through molecular mechanisms are not fully understood. Although biochemical values of some endophytes are well recognized, molecular mechanisms involved in endophytic-induced stress tolerance are poorly known. Fungal endophytes present several important advantages over mycorrhizal fungi including broader host range as well as straightforward isolation and application protocols. Further studies are necessary for selecting the best strains and communities, producing inoculum on a large-scale, and understanding the potential environmental hazards.

eEF1Bγs are proteins found in all eukaryotes and have a role in protein translation, being part of the nucleotide exchange factor eEF1B of the elongation factor complex 1. They are unique because of their organization as a fusion between a glutathione transferase (GST) domain and an elongation factor EF1G (PF00647) domain. The main described function of the GST domain in eEF1Bγ is to ensure the proper scaffolding of the different subunits in the eEF1B complex, by interacting with eEF1Bα subunit. Several evidences also suggest that this domain has a role in cellular redox control because it displays enzymatic activity using glutathione as co-substrate. This opens the question of a dual role of eEF1Bγ in cells both in protein translation and stress response, either in a concomitant or competitive way. By analyzing the diversity of eEF1Bγ sequences in fungi, we show that this class of proteins is subjected to diversification within these microorganisms. The challenge is now to understand the impact of such diversification in eEF1Bγ functions both related to protein translation and stress response, and whether this could have driven the ability of fungi to adapt to constraints.

Chitinases (EC 3.2.1.14) are the glycoside hydrolases (GH) that catalyse the cleavage of β-(1,4) glycosidic linkages of chitin, which is a key element of fungal cell wall and insect's exoskeletons. Fungi have been considered as an excellent source for the production of extracellular chitinases, which could further be employed for chitin degradation to generate a range of bioactive chito-derivatives, i.e., oligosaccharides and glucosamine. Moreover, chitinases have diverse roles in various physiological functions, i.e., autolysis, cell wall remodeling, mycoparasitism and biocontrol. The advent of technology led to the sequencing of several fungal genomes and enabled the manipulation of novel effective chitinase genes to investigate their mechanistic and structural insights to decode the variabilities in chitin degradation. Further, the comprehensible understanding of attributes including substrate-binding sites and catalytic domains could give an insight into chitin catabolism for value-added products development. The review summarized various aspects of fungal chitinases viz. structure, mechanism, classification, properties, functions and application in the present precis. The study has also underlined the recent research related to the framework of substrate-binding clefts in fungal chitinases and its correlation with the hydrolytic and transglycosylation (TG) activity for the production of oligosaccharides with variable degrees of polymerization.

A critical factor in the success of fungal growth is spore adhesion to host surfaces. Generating spores capable of rapid and firm bonding to their hosts is not only important for keeping spores from prematurely detaching from the host surface but can also serve as a trigger for spore germination and the development of infection structures. In this paper fungal spore adhesion mechanisms are reviewed as well as factors influencing spore adhesion, germination, and differentiation. This review ends with a brief discussion on the future of fungal adhesion research.

Hyphae are microscopic filaments that elongate and branch to create networks of interconnected tubes. Understanding how they work remains a formidable challenge in experimental mycology. Important advances in hyphal research in the 20^th century came from electron microscopy, which revealed clusters of cytoplasmic vesicles in the cell apex, and biochemical studies that identified the cell wall materials that are assembled at the tip. Early genetic experiments on hyphae based on mutant analysis were disappointing and provided little information on the relationship between genotype and phenotype. Progress has come more recently, in the first decades of this century, by combining the techniques of molecular genetics with modern imaging methods. Live-cell imaging has allowed us to study the dynamics of cell components in strains of fungi engineered with plasmids encoding proteins fused to fluorescent probes. This technology has provided significant insights on the growth process and yet the fundamentals of hyphal growth remain elusive.

Citriculture is an important economic activity worldwide and for decades, this sector has been responsible for creating job opportunities. Currently, Brazil is the largest orange producer in the world, which contributes to the country's economy. However, citrus production has been facing several issues that compromise the quality of the fruits. For instance, several postharvest diseases occur during storage and transportation, directly harming product marketing. Green mold, blue mold, and sour rot are considered the most common postharvest citrus diseases. Citrus sour rot is less common; however, the disease can lead to a significant loss in high rainfall seasons. The fungus Geotrichum candidum is the causal agent of sour rot and its chemical and biochemical infection strategies are still little explored in citrus fruits. Several conventional control methods, including the application of fungicides, aim to contain the disease proliferation, but most of the commercially available fungicides are not efficient against sour rot. For this reason, other strategies have been studied for disease control, such as chemicals (e. g. essential oils or other natural products), biological agents used as biocontrol, and physical strategies. Despite its importance, few reviews have focused on sour rot disease. Here, we summarize the biochemical aspects of G. candidum, as well as the metabolites produced by this phytopathogen, the known virulence factors, and advances for disease management.

Fungi show a variety of abilities in affecting metal speciation, toxicity, and mobility and mineral formation, dissolution or deterioration through several interacting biomechanical and biochemical mechanisms. A consequence of many metal-mineral interactions is the production of nanoparticles which may be in elemental, mineral or compound forms. Organisms may benefit from such nanomaterial formation through removal of metal toxicity, protection from environmental stress, and their redox properties since certain mycogenic nanoparticles can act as nanozymes mimicking enzymes such as peroxidase. With the development of nanotechnology, there is growing interest in the application of biological systems for nanomaterial production which may provide economic benefits and a lower damaging environmental effect than conventional chemical synthesis. Fungi offer some advantages since most are easily cultured under controlled conditions and well known for the secretion of metabolites and enzymes related to nanoparticle or nanomineral formation. Nanoparticles can be formed intracellularly or extracellularly, the latter being favourable for easy harvest, while the cell wall also provides abundant nucleation sites for their formation. In this article, we focus on the synthesis of nanoparticles and nanominerals by fungi, emphasizing the mechanisms involved, and highlight some possible applications of fungal nanomaterials in environmental biotechnology.

This technical focus article discusses the importance of concentration, cellular exposure and specificity for the application of organelle selective fluorescent dyes in fungi using DNA, membrane and cell wall stains as examples. Nonetheless, the presented considerations are generally applicable to all fluorescent dyes applied to living cells.

The association of a fluorescent dye with its target molecule generally impairs molecule and consequently organelle function. Effective dye concentration, cellular exposure time and specificity to the target molecule are key factors that influence the biocompatibility of any fluorescent dye. Prominent molecules frequently used as fluorescent staining targets in fungal cell biology are: (i) DNA for nuclear labelling, (ii) α-/β-glucans and chitin for cell wall labelling, and (iii) phospholipids for plasma membrane and endomembrane labelling. In combination with live-cell imaging settings that reduce light stress, i.e. excitation intensities and exposure times set to the minimum that still achieves good signal-to-noise ratios, is the low dosage application of fluorescent markers as so called “vital dyes” essential for visualising cellular processes in an artefact-free fashion.

Fungi need water for all stages of life. Notably, mushrooms consist of ∼90% water. Fungi degrade organic matter by secreting enzymes. These enzymes need water to be able to break down the substrate. For instance, when the substrate is too dry, fungi transport water from moist areas to arid areas by hydraulic redistribution. Once nutrients are freed from the substrate, they are taken up by transporters lining the cell membrane. Thereby an intracellular osmotic potential is created which is greater than that of the substrate, and water follows by osmosis. Aquaporins may facilitate water uptake depending on the conditions. Since fungi possess a cell wall, the cell volume will not increase much by water uptake, but the cell membrane will exert higher pressure on the cell wall, thereby building up turgor. Fungi have tightly coordinated osmotic regulatory controls via the HOG pathway. When water is getting scarce, this pathway makes sure that enough osmolytes are synthesized to allow sufficient water uptake for maintaining turgor homeostasis. The fungal network is interconnected and allows water flow when small pressure differences exist. These pressure differences can be the result of growth, differential osmolyte uptake/synthesis or external osmotic conditions. Overall, the water potential of the substrate and of fungal tissues determine whether water will flow, since water flows from an area of high- to a low water potential area, when unobstructed. In this review we aim to give a comprehensive view on how fungi obtain and translocate water needed for their development. We have taken Agaricus bisporus growing on compost and casing soil as a case study, to discuss water relations during fruiting in detail. Using the current state-of-the-art we found that there is a discrepancy between the models describing water transport to mushrooms and the story that water potentials tell us.