•We discuss the current lifestyle designations of plant pathogenic fungi.•Host defenses may influence lifestyle transitions in hemi-biotrophs.•Sclerotinia sclerotiorum is not a typical necrotroph.•We ...discuss combining fungal lifestyle attributes with damage response curves.
Plants and fungi have had many years of friendly and not-so friendly competition for resources and quality of life. As a result, diverse pathosystems evolved numerous strategies, coupled with the emergence of multifaceted pathogenic and saprophytic lifestyles. We discuss fungal lifestyle classifications and how the views associated with certain fungal pathogens, particularly necrotophs, are changing as we learn more about the complexities of their interactions with a given host plant. We discuss the physiological events leading to the transition from biotrophy to necrotrophy in hemi-biotrophs, and conclude that both the control of plant immune responses and the need for a more efficient mode of nutrient acquisition are possible triggers for the transition to necrotrophy. Based on recent findings, we focus on the polyphagous plant pathogen Sclerotinia sclerotiorum. Rather than overwhelming plant foes, S. sclerotiorum has evolved clever means to compromise host recognition and establish disease, resulting in a broad and immensely successful pathogenic lifestyle. The tactics used by this fungus to achieve pathogenic success are being clarified. We propose that the hemi-biotrophic lifestyle may be more temporally and spatially complex than currently depicted, and that combining lifestyle attributes with damage response curves that consider the contribution of both the fungus and the host to pathogenesis, may provide a more holistic manner to view plant pathogens.
Mushrooms of the genus Pleurotus are comprised of cultivated edible ligninolytic fungi with medicinal properties and a wide array of biotechnological and environmental applications. Like other ...white-rot fungi (WRF), they are able to grow on a variety of lignocellulosic biomass substrates and degrade both natural and anthropogenic aromatic compounds. This is due to the presence of the non-specific oxidative enzymatic systems, which are mainly consisted of lacasses, versatile peroxidases (VPs), and short manganese peroxidases (short-MnPs). Additional, less studied, peroxidase are dye-decolorizing peroxidases (DyPs) and heme-thiolate peroxidases (HTPs). During the past two decades, substantial information has accumulated concerning the biochemistry, structure and function of the Pleurotus ligninolytic peroxidases, which are considered to play a key role in many biodegradation processes. The production of these enzymes is dependent on growth media composition, pH, and temperature as well as the growth phase of the fungus. Mn²⁺concentration differentially affects the expression of the different genes. It also severs as a preferred substrate for these preoxidases. Recently, sequencing of the Pleurotus ostreatus genome was completed, and a comprehensive picture of the ligninolytic peroxidase gene family, consisting of three VPs and six short-MnPs, has been established. Similar enzymes were also discovered and studied in other Pleurotus species. In addition, progress has been made in the development of molecular tools for targeted gene replacement, RNAi-based gene silencing and overexpression of genes of interest. These advances increase the fundamental understanding of the ligninolytic system and provide the opportunity for harnessing the unique attributes of these WRF for applied purposes.
Small secreted proteins (SSPs) comprise 40-60% of the total fungal secretome and are present in fungi of all phylogenetic groups, representing the entire spectrum of lifestyles. They are ...characteristically shorter than 300 amino acids in length and have a signal peptide. The majority of SSPs are coded by orphan genes, which lack known domains or similarities to known protein sequences. Effectors are a group of SSPs that have been investigated extensively in fungi that interact with living hosts, either pathogens or mutualistic systems. They are involved in suppressing the host defense response and altering its physiology. Here, we aim to delineate some of the potential roles of SSPs in saprotrophic fungi, that have been bioinformatically predicted as effectors, and termed in this mini-review as "effector-like" proteins. The effector-like Ssp1 from the white-rot fungus
is presented as a case study, and its potential role in regulating the ligninolytic system, secondary metabolism, development, and fruiting body initiation are discussed. We propose that deciphering the nature of effector-like SSPs will contribute to our understanding of development and communication in saprophytic fungi, as well as help, to elucidate the origin, regulation, and mechanisms of fungal-host, fungal-fungal, and fungal-bacterial interactions.
Impairment of the
Neurospora crassa
Nuclear DBF2-related kinase-encoding gene
cot
-
1
results in pleiotropic effects, including abnormally thick hyphal cell walls and septa. An increase in the ...transcript abundance of genes encoding chitin and glucan synthases and the chitinase
gh18
-
5
, but not the cell wall integrity pathway transcription factor
rlm
-
1
, accompany the phenotypic changes observed. Deletion of
chs
-
5
or
chs
-
7
in a
cot
-
1
background results in a reduction of hyperbranching frequency characteristic of the
cot
-
1
parent.
gul
-
1
(a homologue of the yeast
SSD1
gene) encodes a translational regulator and has been shown to partially suppress
cot
-
1
. We demonstrate that the high expression levels of the cell wall remodeling genes analyzed is curbed, and reaches near wild type levels, when
gul
-
1
is inactivated. This is accompanied by morphological changes that include reduced cell wall thickness and restoration of normal chitin levels. We conclude that
gul
-
1
is a mediator of cell wall remodeling within the
cot
-
1
pathway.
Terrestrial fungi play critical roles in nutrient cycling and food webs and can shape macroorganism communities as parasites and mutualists. Although estimates for the number of fungal species on the ...planet range from 1.5 to over 5 million, likely fewer than 10% of fungi have been identified so far. To date, a relatively small percentage of described species are associated with marine environments, with ∼1,100 species retrieved exclusively from the marine environment. Nevertheless, fungi have been found in nearly every marine habitat explored, from the surface of the ocean to kilometers below ocean sediments. Fungi are hypothesized to contribute to phytoplankton population cycles and the biological carbon pump and are active in the chemistry of marine sediments. Many fungi have been identified as commensals or pathogens of marine animals (e.g., corals and sponges), plants, and algae. Despite their varied roles, remarkably little is known about the diversity of this major branch of eukaryotic life in marine ecosystems or their ecological functions. This perspective emerges from a Marine Fungi Workshop held in May 2018 at the Marine Biological Laboratory in Woods Hole, MA. We present the state of knowledge as well as the multitude of open questions regarding the diversity and function of fungi in the marine biosphere and geochemical cycles.
Understanding the chemical interactions of common allergens in urban environments may help to decipher the general increase in susceptibility to allergies observed in recent decades. In this study, ...asexual conidia of the allergenic mold Aspergillus fumigatus were exposed to air pollution under natural (ambient) and controlled (laboratory) conditions. The allergenic activity was measured using two immunoassays and supported by a protein mass spectrometry analysis. The allergenicity of the conidia was found to increase by 2–5 fold compared to the control for short exposure times of up to 12h (accumulated exposure of about 50ppb NO2 and 750ppb O3), possibly due to nitration. At higher exposure times, the allergenicity increase lessened due to protein deamidation. These results indicate that during the first 12h of exposure, the allergenic potency of the fungal allergen A. fumigatus in polluted urban environments is expected to increase. Additional work is needed in order to determine if this behavior occurs for other allergens.
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•Short-term exposure to urban air pollution increases A. fumigatus allergenicity.•The effect is most significant during the first hours due to nitration of proteins.•At longer exposure time allergenicity reduces, possibly due to protein deamidation.
Fungi transcriptionally upregulate expression of azole efflux pumps and ergosterol biosynthesis pathway genes when exposed to antifungal agents that target ergosterol biosynthesis. To date, these ...transcriptional responses have been shown to be dependent on the presence of the azoles and/or depletion of ergosterol. Using an inducible promoter to regulate
, which encodes the major azole target, sterol 14α-demethylase, we were able to demonstrate that the CDR4 azole efflux pump can be transcriptionally activated by ergosterol biosynthesis inhibition even in the absence of azoles. By analyzing ergosterol deficient mutants, we demonstrate that the transcriptional responses by
and, unexpectedly, genes encoding ergosterol biosynthesis enzymes (
genes) that are responsive to azoles, are not dependent on ergosterol depletion. Nonetheless, deletion of
, which encodes C-8 sterol isomerase, also induced expression of
. Deletion of
also induced the expression of
, the gene encoding C-14 sterol reductase, but not other tested
genes which were responsive to
inactivation. This indicates that inhibition of specific steps of ergosterol biosynthesis can result in different transcriptional responses, which is further supported by our results obtained using different ergosterol biosynthesis inhibitors. Together with the sterol profiles, these results suggest that the transcriptional responses by
and
genes are associated with accumulation of specific sterol intermediate(s). This was further supported by the fact that when the
mutant was treated with ketoconazole, upstream inhibition overrode the effects by downstream inhibition on ergosterol biosynthesis pathway. Even though
expression is associated with the accumulation of sterol intermediates, intra- and extracellular sterol analysis by HPLC-MS indicated that the transcriptional induction of
did not result in efflux of the accumulated intermediate(s). This study demonstrates, by detailed genetic and chemical analysis, that transcriptional responses by a major efflux pump and genes of the ergosterol biosynthesis pathway to ergosterol biosynthesis inhibitors can be independent of the presence of the drugs and are linked with the accumulation of ergosterol intermediate(s).
COT1 is the founding member of the highly conserved nuclear Dbf2-related (NDR) Ser/Thr kinase family and plays a role in the regulation of polar growth and development in
and other fungi. Changes in ...COT1 phosphorylation state have been shown to affect hyphal elongation, branching, and conidiation. The function of NDR protein kinases has been shown to be regulated by type 2A protein phosphatases (PP2As). PP2As are heterotrimers comprised of a catalytic and scaffolding protein along with an interchangeable regulatory subunit involved in determining substrate specificity. Inactivation of the
PP2A regulatory subunits
and
conferred severe hyphal growth defects. Partial suppression of defects observed in the
strain (but not in the Δ
mutant) was observed in
phosphomimetic mutants, demonstrating that altering COT1 phosphorylation state can bypass, at least in part, the requirement of a functional RGB1 subunit. The functional fusion proteins RGB1::GFP and B56::GFP predominantly localized to hyphal tips and septa, respectively, indicating that their primary activity is in different cellular locations. COT1 protein forms exhibited a hyperphosphorylated gel migration pattern in an
mutant background, similar to that observed when the fungus was cultured in the presence of the PP2A inhibitor cantharidin. COT1 was hypophosphorylated in a Δ
mutant background, suggesting that this regulatory subunit may be involved in determining COT1 phosphorylation state, yet in an indirect manner. Reciprocal co-immunoprecipitation analyses, using tagged COT1, PPH1, RGB1, and B56 subunits established that these proteins physically interact. Taken together, our data determine the presence of a functional and physical link between PP2A and COT1 and show that two of the PP2A regulatory subunits interact with the kinase and determine COT1 phosphorylation state.
Fungi have the ability to transform organic materials into a rich and diverse set of useful products and provide distinct opportunities for tackling the urgent challenges before all humans. Fungal ...biotechnology can advance the transition from our petroleum-based economy into a bio-based circular economy and has the ability to sustainably produce resilient sources of food, feed, chemicals, fuels, textiles, and materials for construction, automotive and transportation industries, for furniture and beyond. Fungal biotechnology offers solutions for securing, stabilizing and enhancing the food supply for a growing human population, while simultaneously lowering greenhouse gas emissions. Fungal biotechnology has, thus, the potential to make a significant contribution to climate change mitigation and meeting the United Nation's sustainable development goals through the rational improvement of new and established fungal cell factories. The White Paper presented here is the result of the 2nd Think Tank meeting held by the EUROFUNG consortium in Berlin in October 2019. This paper highlights discussions on current opportunities and research challenges in fungal biotechnology and aims to inform scientists, educators, the general public, industrial stakeholders and policymakers about the current fungal biotech revolution.
Lineage-specific genes (LSGs) have long been postulated to play roles in the establishment of genetic barriers to intercrossing and speciation. In the genome of Neurospora crassa, most of the 670 ...Neurospora LSGs that are aggregated adjacent to the telomeres are clustered with 61% of the HET-domain genes, some of which regulate self-recognition and define vegetative incompatibility groups. In contrast, the LSG-encoding proteins possess few to no domains that would help to identify potential functional roles. Possible functional roles of LSGs were further assessed by performing transcriptomic profiling in genetic mutants and in response to environmental alterations, as well as examining gene knockouts for phenotypes. Among the 342 LSGs that are dynamically expressed during both asexual and sexual phases, 64% were detectable on unusual carbon sources such as furfural, a wildfire-produced chemical that is a strong inducer of sexual development, and the structurally-related furan 5-hydroxymethyl furfural (HMF). Expression of a significant portion of the LSGs was sensitive to light and temperature, factors that also regulate the switch from asexual to sexual reproduction. Furthermore, expression of the LSGs was significantly affected in the knockouts of adv-1 and pp-1 that regulate hyphal communication, and expression of more than one quarter of the LSGs was affected by perturbation of the mating locus. These observations encouraged further investigation of the roles of clustered lineage-specific and HET-domain genes in ecology and reproduction regulation in Neurospora, especially the regulation of the switch from the asexual growth to sexual reproduction, in response to dramatic environmental conditions changes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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