Fungal Transcription Factors Research Articles

Morpho-Molecular and Genomic Characterization of Penicillium mexicanum Isolates Retrieved from a Forsaken Gold Mine

During the ongoing studies designed to examine the fungal diversity present within the abandoned and flooded Escádia Grande gold mine (Góis, Portugal), we repeatedly isolated several specimens belonging to a Penicillium species. Molecular phylogenetic analysis, coupled with morphological observations, positioned this fungus within subgen. Penicillium sect. Paradoxa, series Atramentosa, pinpointing its identity as Penicillium mexicanum (the first record for mining soils and the country). Given the limited research conducted on Penicillia isolated from similar environments, the species genome was sequenced utilizing the Oxford Nanopore® MinION™ methodology and studied through bioinformatic analysis. The obtained genome has a size of 29.62 Mb, containing a 47.72% GC content, 10,156 genes, with 44 rRNAs and 178 tRNAs/tmRNAs, providing the first genomic resource for this microorganism. Bioinformatic analysis allowed us to identify multiple genomic traits that can contribute towards this species survival in these extreme environments, including the presence of high levels of major facilitator transporters (MFS), Zn (2)-C6 fungal-type DNA-binding domains, P-loop containing nucleoside triphosphate hydrolases, specific fungal transcription factors and sugar transporters. Furthermore, putative advantageous metabolic traits, such as methylotrophy, assimilatory nitrate and sulfate reduction abilities, were also detected. In addition, the results also highlighted a strong genomic and metabolic organization and investment towards arsenic detoxification (transport and oxidation). Lastly, thirty-two putative biosynthetic gene clusters were predicted, including some with high similarity values to monascorubrin, nidulanin A, histidyltryptophanyldiketopiperazine/dehydrohistidyltryptophanyldiketopiperazine/roquefortine D/roquefortine C/glandicoline A/glandicoline B/meleagrine, YWA1 and choline. Overall, this study expands the current Penicillia knowledge from mining environments while also enhancing our understanding regarding fungal arsenic resistance.

Identification of Homeobox Transcription Factors in a Dimorphic Fungus Talaromyces marneffei and Protein-Protein Interaction Prediction of RfeB.

Talaromyces marneffei is a thermally dimorphic fungus that can cause life-threatening systemic mycoses, particularly in immunocompromised individuals. Fungal homeobox transcription factors control various developmental processes, including the regulation of sexual reproduction, morphology, metabolism, and virulence. However, the function of homeobox proteins in T. marneffei has not been fully explored. Here, we searched the T. marneffei genome for the total homeobox transcription factors and predicted their biological relevance by performing gene expression analysis in different cell types, including conidia, mycelia, yeasts, and during phase transition. RfeB is selected for further computational analysis since (i) its transcripts were differentially expressed in different phases of T. marneffei, and (ii) this protein contains the highly conserved protein-protein interaction region (IR), which could be important for pathobiology and have therapeutic application. To assess the structure-function of the IR region, in silico alanine substitutions were performed at three-conserved IR residues (Asp276, Glu279, and Gln282) of RfeB, generating a triple RfeB mutated protein. Using 3D modeling and molecular dynamics simulations, we compared the protein complex formation of wild-type and mutated RfeB proteins with the putative partner candidate TmSwi5. Our results demonstrated that the mutated RfeB protein exhibited increased free binding energy, elevated protein compactness, and a reduced number of atomic contacts, suggesting disrupted protein stability and interaction. Notably, our model revealed that the IR residues primarily stabilized the RfeB binding sites located in the central region (CR). This computational approach for protein mutagenesis could provide a foundation for future experimental studies on the functional characterization of RfeB and other homeodomain-containing proteins in T. marneffei.

The Fungal Transcription Factor BcTbs1 from Botrytis cinerea Promotes Pathogenicity via Host Cellulose Degradation.

Zn(II)2Cys6 proteins constitute the largest group of fungal-specific transcription factors. However, little is known about their functions in the crop killer Botrytis cinerea. In this work, a T-DNA insertion strain M13448 was identified which was inserted into the Zn(II)2Cys6 TF-encoding gene BcTBS1. Knockout of BcTBS1 did not affect mycelia growth, appressorium formation, and sclerotium germination, but impaired fungal conidiation, conidial morphogenesis, conidial germination, infection cushion development, and sclerotial formation. Accordingly, ΔBctbs1 mutants showed reduced virulence in its host plants. Further study proved that BcTBS1, BCIN_15g03870, and BCIN_12g06630 were induced by cellulose. Subsequent cellulase activity assays revealed that the loss of BcTBS1 significantly decreased cellulase activity. In addition, we verified that the BCIN_15g03870 and BCIN_12g06630 genes were positive regulated by BcTBS1 by quantitative real-time reverse-transcription-polymerase chain reaction (qRT-PCR). Taken together, these results suggested that BcTBS1 can promote pathogenicity by modulating cellulase-encoding genes that participate in host cellulose degradation.

Novel Botrytis cinerea Zn(II)2Cys6 Transcription Factor BcFtg1 Enhances the Virulence of the Gray Mold Fungus by Promoting Organic Acid Secretion and Carbon Source Utilization.

The Zn(II)2Cys6 zinc cluster protein family comprises a subclass of zinc-finger proteins that serve as transcriptional regulators involved in a diverse array of fugal biological processes. However, the roles and mechanisms of the Zn(II)2Cys6 transcription factors in mediating Botrytis cinerea, a necrotrophic fungus that causes gray mold in over 1000 plant species, development and virulence remain obscure. Here, we demonstrate that a novel B. cinerea pathogenicity-associated factor BcFTG1 (fungal transcription factor containing the GAL4 domain), identified from a virulence-attenuated mutant M20162 from a B. cinerea T-DNA insertion mutant library, plays an important role in oxalic acid (OA) secretion, carbon source absorption and cell wall integrity. Loss of BcFTG1 compromises the ability of the pathogen to secrete OA, absorb carbon sources, maintain cell wall integrity, and promote virulence. Our findings provide novel insights into fungal factors mediating the pathogenesis of the gray mold fungus via regulation of OA secretion, carbon source utilization and cell wall integrity.

The Velvet transcription factor PnVeA regulates necrotrophic effectors and secondary metabolism in the wheat pathogen Parastagonospora nodorum

The fungus Parastagonospora nodorum causes septoria nodorum blotch on wheat. The role of the fungal Velvet-family transcription factor VeA in P. nodorum development and virulence was investigated here. Deletion of the P. nodorum VeA ortholog, PnVeA, resulted in growth abnormalities including pigmentation, abolished asexual sporulation and highly reduced virulence on wheat. Comparative RNA-Seq and RT-PCR analyses revealed that the deletion of PnVeA also decoupled the expression of major necrotrophic effector genes. In addition, the deletion of PnVeA resulted in an up-regulation of four predicted secondary metabolite (SM) gene clusters. Using liquid-chromatography mass-spectrometry, it was observed that one of the SM gene clusters led to an accumulation of the mycotoxin alternariol. PnVeA is essential for asexual sporulation, full virulence, secondary metabolism and necrotrophic effector regulation.

In silico prediction of polyketide biosynthetic gene clusters in the genomes of Hypericum-borne endophytic fungi

BackgroundThe search for new bioactive natural compounds with anticancer activity is still of great importance. Even though their potential for diagnostics and treatment of cancer has already been proved, the availability is still limited. Hypericin, a naphthodianthrone isolated essentially from plant source Hypericum perforatum L. along with other related anthraquinones and bisanthraquinones belongs to this group of compounds. Although it has been proven that hypericin is synthesized by the polyketide pathway in plants, none of the candidate genes coding for key enzymes has been experimentally validated yet. Despite the rare occurrence of anthraquinones in plants, their presence in microorganisms, including endophytic fungi, is quite common. Unlike plants, several biosynthetic genes grouped into clusters (BGCs) in fungal endophytes have already been characterized.ResultsThe aim of this work was to predict, identify and characterize the anthraquinone BGCs in de novo assembled and functionally annotated genomes of selected endophytic fungal isolates (Fusarium oxysporum, Plectosphaerella cucumerina, Scedosporium apiospermum, Diaporthe eres, Canariomyces subthermophilus) obtained from different tissues of Hypericum spp. The number of predicted type I polyketide synthase (PKS) BGCs in the studied genomes varied. The non-reducing type I PKS lacking thioesterase domain and adjacent discrete gene encoding protein with product release function were identified only in the genomes of C. subthermophilus and D. eres. A candidate bisanthraquinone BGC was predicted in C. subthermophilus genome and comprised genes coding the enzymes that catalyze formation of the basic anthraquinone skeleton (PKS, metallo-beta-lactamase, decarboxylase, anthrone oxygenase), putative dimerization enzyme (cytochrome P450 monooxygenase), other tailoring enzymes (oxidoreductase, dehydrogenase/reductase), and non-catalytic proteins (fungal transcription factor, transporter protein).ConclusionsThe results provide an insight into genetic background of anthraquinone biosynthesis in Hypericum-borne endophytes. The predicted bisanthraquinone gene cluster represents a basis for functional validation of the candidate biosynthetic genes in a simple eukaryotic system as a prospective biotechnological alternative for production of hypericin and related bioactive anthraquinones.

Positive selection and functional diversification of transcription factor Cmr1 homologs in Alternaria

Transcription factor Cmr1 (Colletotrichum melanin regulation 1) and its homologs in several plant fungal pathogens are the regulators of the 1,8-dihydroxynaphthalene (DHN)-melanin biosynthesis pathway and have evolved functional diversification in morphology and pathogenicity. The fungal genus Alternaria comprises the group of “black fungi” that are rich in DHN-melanin in the primary cell wall and septa of the conidia. Some Alternaria species cause many economically important plant diseases worldwide. However, the evolution and function of Cmr1 homologs in Alternaria remain poorly understood. Here, we identified a total of forty-two Cmr1 homologs from forty-two Alternaria spp. and all contained one additional diverse fungal specific transcription factor motif. Phylogenetic analysis indicated the division of these homologs into five major clades and three branches. Dated phylogeny showed the A and D clades diverged latest and earliest, respectively. Molecular evolutionary analyses revealed that three amino acid sites of Cmr1 homologs in Alternaria were the targets of positive selection. Asmr1, the homolog of Cmr1 in the potato early blight pathogen, Alternaria solani was amplified and displayed the sequence conservation at the amino acid level in different A. solani isolates. Asmr1 was further confirmed to have the transcriptional activation activity and was upregulated during the early stage of potato infection. Deletion of asmr1 led to the decreased melanin content and pathogenicity, deformed conidial morphology, and responses to cell wall and fungicide stresses in A. solani. These results suggest positive selection and functional divergence have played a role in the evolution of Cmr1 homologs in Alternaria.Key points• Cmr1 homologs were under positive selection in Alternaria species• Asmr1 is a functional transcription factor, involved in spore development, melanin biosynthesis, pathogenicity, and responses to cell wall and fungicide stresses in A. solani• Cmr1 might be used as a potential taxonomic marker of the genus Alternaria

Phylogenomics analysis of velvet regulators in the fungal kingdom.

All life forms have evolved to respond appropriately to various environmental and internal cues. In the animal kingdom, the prototypical regulator class of such cellular responses is the Rel homology domain proteins including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Fungi, the close relatives of animals, have also evolved with their own NF-κB-like regulators called velvet family proteins to govern cellular and chemical development. Here, we conducted a detailed investigation of the taxonomic broad presence of velvet proteins. We observed that velvet proteins are widely distributed in the fungal kingdom. Moreover, we have identified and characterized 21 major velvet clades in fungi. We have further revealed that the highly conserved velvet domain is composed of three distinct motifs and acts as an evolutionarily independent domain, which can be shuffled with various functional domains. Such rearrangements of the velvet domain have resulted in the functional and type diversity of the present velvet regulators. Importantly, our in-deep analyses of the primary and 3D structures of the various velvet domains showed that the fungal velvet domains can be divided into two major clans: the VelB and the VosA clans. The 3D structure comparisons revealed a close similarity of the velvet domain with many other eukaryotic DNA-binding proteins, including those of the Rel, Runt, and signal transducer and activator of transcription families, sharing a common β-sandwich fold. Altogether, this study improves our understanding of velvet regulators in the fungal kingdom.IMPORTANCEFungi are the relatives of animals in Opisthokonta and closely associated with human life by interactive ways such as pathogenicity, food, and secondary metabolites including beneficial ones like penicillin and harmful ones like the carcinogenic aflatoxins. Similar to animals, fungi have also evolved with NF-κB-like velvet family regulators. The velvet proteins constitute a large protein family of fungal transcription factors sharing a common velvet domain and play a key role in coordinating fungal secondary metabolism, developmental and differentiation processes. Our current understanding on velvet regulators is mostly from Ascomycota fungi; however, they remain largely unknown outside Ascomycota. Therefore, this study performed a taxonomic broad investigation of velvet proteins across the fungal kingdom and conducted a detailed analysis on velvet distribution, structure, diversity, and evolution. The results provide a holistic view of velvet regulatory system in the fungal kingdom.

Влияние малых интерферирующих РНК, синтезированных in vitro, на рост и споруляцию патогенного гриба Stagonospora nodorum

Recently, several RNA interference-based disease prevention mechanisms using small RNAs have been used to protect crops in some countries. Plants secrete small RNAs that directly or indirectly inhibit the virulence of pathogens. In this work, we studied the effect of three wheat microRNAs (miR159, miR166 and miR408) synthesized in vitro on the growth and sporulation of the pathogenic fungus Stagonospora nodorum, as well as on the expression of the genes of the necrotrophic effectors (NEs) S. nodorum SnToxA and SnTox3 (which determine the virulence of the pathogen) and the fungal transcription factors (TFs) Pf2, StuA, Con7 regulating the transcription of NE genes. It was shown that the addition of microRNAs in various concentrations into the fungal cultivation medium affected the growth of colonies and sporulation of the pathogen. miR166 had the greatest impact on these parameters. Using gene-specific primers, PCR analysis was carried out, which showed that the effect of microRNA on the expression of the genes encoding NEs and TFs of the pathogenic fungus S. nodorum depended on the type and concentration of microRNA in the medium. Thus, 0.5 ng/μl of ssRNA408 reduced the expression of all the studied NEs and TFs genes on the 7th day of cultivation. Further comprehensive studies of the mechanisms of cross-species regulation using miRNAs may help in the development of new pesticides for modern agriculture.

Transcriptional response of the white-rot fungus Dichomitus squalens to polysaccharides reveals a co-expression network of plant biomass conversion related genes

Wood-degrading white-rot fungi can efficiently degrade all plant biomass components, but the molecular mechanisms behind the degradation of plant polysaccharides remain poorly understood. For example, the gene sets and expression levels induced by the plant polysaccharide-derived monosaccharides in white-rot fungi do not reflect those induced by crude plant biomass substrates. To explore the molecular response of the white-rot fungus Dichomitus squalens to plant-derived oligo- and polysaccharides, we investigated the transcriptomes from mono- and dikaryotic strains of the fungus on 10 substrates and compared the expression of carbohydrate-active enzyme-encoding genes to that previously reported for different monosaccharides and cellobiose. Our results revealed that in D. squalens, a robust response to cellulose leads to its effective depolymerization, with an orthologue of the ascomycete Trichoderma reesei ACE3 likely acting as a central transcriptional regulator. The conserved response between cellulose and cellobiose further confirms cellobiose as the main cellulase inducer in D. squalens. Surprisingly, despite low abundance of pectin in the natural wood substrate of D. squalens, we identified polygalacturonic acid as a major inducer of a broad-targeted pectinolytic response including pectinase, pectin-related sugar transporter and catabolism genes, and four fungal specific transcription factors. This indicates that D. squalens has not only maintained its ability to degrade minor polysaccharide components in its biotope, but also a regulatory system spanning from extracellular degradation to metabolic conversion. Our study contributes to a deeper understanding of the molecular mechanisms behind white-rot fungal plant polysaccharide degradation and provides leads for functional studies of potential transcriptional regulators in basidiomycetes.

Discovery of novel plant biomass conversion associated fungal transcription factors using a network-based approach

Fungal plant biomass conversion (FPBC) is an important component of the global carbon cycle and has been widely applied for the production of biofuels, enzymes and biochemicals. Identification of transcription factors (TFs) governing FPBC is crucial for genetic engineering of industrial fungi towards sustainable production of high-value bioproducts from renewable lignocellulose. Here, we developed a bioinformatics framework for the identification of FPBC related TFs based on reconstructed gene regulatory networks and enrichment analysis of manually curatedFPBC gene sets. Applying this approach to model fungi Aspergillus niger and Neurospora crassa, we successfully identified both known TFs and promising candidates. The function of one identified TF, HapX, has been experimentally validated, and several candidates were supported by literature, transcriptome data and initial growth analysis. Our new approach will accelerate the identification of novel TFs involved in FPBC, and facilitate the further improvement of fungal cell factories.

Whole-Genome Sequencing of Fusarium oxysporum f. sp. cucumerinum Strain Race-4 Infecting Cucumber in China.

Fusarium oxysporum f. sp. cucumerinum, which causes root and vascular wilting, is one of the most devastating diseases infecting cucumber. Here, we report the first genome resource with high-quality assembly for F. oxysporum f. sp. cucumerinum strain Race-4, which is primarily endemic to China. The genome was 59.11 Mb in size and consisted of 48 scaffolds with an N50 of 3.87 Mb using PacBio long reads (301.77×) sequencing, and encodes 14,898 proteins from analyzing RNA-seq data. Gene annotations identified pathogen-host interaction genes, fungal virulence factors, secreted proteins, transcription factors, and secondary metabolite biosynthesis gene. Moreover, functional genes reported in previous studies were also identified in the genome of Race-4. These genes and genome resource may play important roles in understanding F. oxysporum f. sp. cucumerinum-cucumber interactions and will be useful for further research.

Utilization of ferulic acid in Aspergillus niger requires the transcription factor FarA and a newly identified Far-like protein (FarD) that lacks the canonical Zn(II)2Cys6 domain.

The feruloyl esterase B gene (faeB) is specifically induced by hydroxycinnamic acids (e.g. ferulic acid, caffeic acid and coumaric acid) but the transcriptional regulation network involved in faeB induction and ferulic acid metabolism has only been partially addressed. To identify transcription factors involved in ferulic acid metabolism we constructed and screened a transcription factor knockout library of 239 Aspergillus niger strains for mutants unable to utilize ferulic acid as a carbon source. The ΔfarA transcription factor mutant, already known to be involved in fatty acid metabolism, could not utilize ferulic acid and other hydroxycinnamic acids. In addition to screening the transcription factor mutant collection, a forward genetic screen was performed to isolate mutants unable to express faeB. For this screen a PfaeB-amdS and PfaeB-lux613 dual reporter strain was engineered. The rationale of the screen is that in this reporter strain ferulic acid induces amdS (acetamidase) expression via the faeB promoter resulting in lethality on fluoro-acetamide. Conidia of this reporter strain were UV-mutagenized and plated on fluoro-acetamide medium in the presence of ferulic acid. Mutants unable to induce faeB are expected to be fluoro-acetamide resistant and can be positively selected for. Using this screen, six fluoro-acetamide resistant mutants were obtained and phenotypically characterized. Three mutants had a phenotype identical to the farA mutant and sequencing the farA gene in these mutants indeed showed mutations in FarA which resulted in inability to growth on ferulic acid as well as on short and long chain fatty acids. The growth phenotype of the other three mutants was similar to the farA mutants in terms of the inability to grow on ferulic acid, but these mutants grew normally on short and long chain fatty acids. The genomes of these three mutants were sequenced and allelic mutations in one particular gene (NRRL3_09145) were found. The protein encoded by NRRL3_09145 shows similarity to the FarA and FarB transcription factors. However, whereas FarA and FarB contain both the Zn(II)2Cys6 domain and a fungal-specific transcription factor domain, the protein encoded by NRRL3_09145 (FarD) lacks the canonical Zn(II)2Cys6 domain and possesses only the fungal specific transcription factor domain.

Cmcrf1, a Putative Zn2Cys6 Fungal Transcription Factor, Is Involved in Conidiation, Carotenoid Production, and Fruiting Body Development in Cordyceps militaris.

Cordyceps militaris is a high-value medicinal and edible fungus that produces many bioactive compounds, including carotenoid, and thus, improving the carotenoid productivity of C. militaris will increase its commercial value. However, little is known about the genetic regulatory mechanism of carotenoid biosynthesis in C. militaris. To further understanding the regulatory mechanism of carotenoid biosynthesis, we performed a large-scale screen of T-DNA insertional mutant library and identified a defective mutant, denoted T111, whose colonies did not change color from white to yellow upon exposure to light. Mutation analysis confirmed that a single T-DNA insertion occurred in the gene encoding a 695-amino-acid putative fungal-specific transcription factor with a predicted Zn2Cys6 binuclear cluster DNA-binding domain found uniquely in fungi. Targeted deletion of this gene, denoted C. militaris carotenogenesis regulatory factor 1 (Cmcrf1), generated the ΔCmcrf1 mutant that exhibited drastically reduced carotenoid biosynthesis and failed to generate fruiting bodies. In addition, the ΔCmcrf1 mutant showed significantly increased conidiation and increased hypersensitivity to cell-wall-perturbing agents compared with the wild-type strain. However, the Cmcrf1 gene did not have an impact on the mycelia growth of C. militaris. These results show that Cmcrf1 is involved in carotenoid biosynthesis and is required for conidiation and fruiting body formation in C. militaris.

Structural basis for activation of fungal sterol receptor Upc2 and azole resistance.

Fungal transcription factor Upc2 senses ergosterol levels and regulates sterol biosynthesis and uptake. Constitutive activation of Upc2 causes azole resistance in Candida species. We determined the structure of ergosterol-bound Upc2, revealing the ligand specificity and transcriptional regulation. Ergosterol binding involves conformational changes of the ligand-binding domain, creating a shape-complementary hydrophobic pocket. The conserved helix α12 and glycine-rich loop are critical for sterol recognition by forming the pocket wall. The mutations of the glycine-rich loop inhibit ligand binding by steric clashes and constitutively activate Upc2. The translocation of Upc2 is regulated by Hsp90 chaperone in a sterol-dependent manner. Ergosterol-bound Upc2 associates with Hsp90 using the C-terminal tail, which retains the inactive Upc2 in the cytosol. Ergosterol dissociation induces a conformational change of the C-terminal tail, releasing Upc2 from Hsp90 for nuclear transport by importin α. The understanding of the regulatory mechanism provides an antifungal target for the treatment of azole-resistant Candida infections.

Tec1 and Ste12 transcription factors play a role in adaptation to low pH stress and biofilm formation in the human opportunistic fungal pathogen Candida glabrata.

Eukaryotic cells respond to environmental cues through mitogen activated protein kinase (MAPK) signaling pathways. Each MAPK cascade is specific to particular stimuli and mediates specialized responses through activation of transcription factors. In the budding yeast, Saccharomyces cerevisiae, the pheromone-induced mating pathway and the starvation-responsive invasive growth/filamentation pathway generate their distinct outputs through the transcription factors Ste12 and Tec1, respectively. In this study, we report the functional characterization of these transcription factors in the closely related human opportunistic pathogenic yeast Candida glabrata. Two homologues each for S. cerevisiae TEC1 and STE12 were identified in C. glabrata. Both C. glabrata Tec1 proteins contain the N-terminal TEA DNA-binding domain characteristic of the TEA/ATTS transcription factor family. Similarly, the DNA-binding homeodomain shared by members of the highly conserved fungal Ste12 transcription factor family is present in N-terminus of both C. glabrata Ste12 transcription factors. We show that both C. glabrata STE12 genes are at least partial functional orthologues of S. cerevisiae STE12 as they can rescue the mating defect of haploid S. cerevisiae ste12 null mutant. Knockout of one of the STE12 genes (ORF CAGL0H02145g) leads to decreased biofilm development; a stronger biofilm-impaired phenotype results from loss of both CgSTE12 genes in the double deletion mutant (Cgste12ΔΔ). The transcript levels of one of the TEC1 genes (ORF CAGL0M01716g) were found to be upregulated upon exposure to low pH; its deletion causes slightly increased sensitivity to higher concentrations of acetic acid. Heat shock leads to increase in mRNA levels of one of the STE12 genes (ORF CAGL0M01254g). These findings suggest a role of Tec1 and Ste12 transcription factors in the regulation of some traits (biofilm formation, response to low pH stress and elevated temperature) that contribute to C. glabrata's ability to colonize various host niches and to occasionally cause disease.

Functional Characterization of the GATA-Type Transcription Factor PaNsdD in the Filamentous Fungus Podospora anserina and Its Interplay with the Sterigmatocystin Pathway.

ABSTRACTThe model ascomycete Podospora anserina, distinguished by its strict sexual development, is a prolific but yet unexploited reservoir of natural products. The GATA-type transcription factor NsdD has been characterized by the role in balancing asexual and sexual reproduction and governing secondary metabolism in filamentous fungi. In the present study, we functionally investigated the NsdD ortholog PaNsdD in P. anserina. Compared to the wild-type strain, vegetative growth, ageing processes, sexual reproduction, stress tolerance, and interspecific confrontations in the mutant were drastically impaired, owing to the loss of function of PaNsdD. In addition, the production of 3-acetyl-4-methylpyrrole, a new metabolite identified in P. anserina in this study, was significantly inhibited in the ΔPaNsdD mutant. We also demonstrated the interplay of PaNsdD with the sterigmatocystin biosynthetic gene pathway, especially as the deletion of PaNsdD triggered the enhanced red-pink pigment biosynthesis that occurs only in the presence of the core polyketide synthase-encoding gene PaStcA of the sterigmatocystin pathway. Taken together, these results contribute to a better understanding of the global regulation mediated by PaNsdD in P. anserina, especially with regard to its unexpected involvement in the fungal ageing process and its interplay with the sterigmatocystin pathway.IMPORTANCE Fungal transcription factors play an essential role in coordinating multiple physiological processes. However, little is known about the functional characterization of transcription factors in the filamentous fungus Podospora anserina. In this study, a GATA-type regulator PaNsdD was investigated in P. anserina. The results showed that PaNsdD was a key factor that can control the fungal ageing process, vegetative growth, pigmentation, stress response, and interspecific confrontations and positively regulate the production of 3-acetyl-4-methylpyrrole. Meanwhile, a molecular interaction was implied between PaNsdD and the sterigmatocystin pathway. Overall, loss of function of PaNsdD seems to be highly disadvantageous for P. anserina, which relies on pure sexual reproduction in a limited life span. Therefore, PaNsdD is clearly indispensable for the survival and propagation of P. anserina in its complex ecological niches.

Molecular characterization of Zn(II)2Cys6 cluster gene family and their association with pathogenicity of the onion basal rot pathogen, Fusarium oxysporum f. sp. cepae

The molecular determinants of Foc (Fusarium oxysporum f. sp. cepae) pathogenicity are highly underexplored. The Zn(II)2Cys6 (C6) subclass of zinc finger proteins are an exclusive group of transcriptional regulators associated with multiple physiological processes including development and pathogenicity in fungi. In the present study, we used a genome-wide approach and detected 398C6-type genes (FOXCZF1-398) distributed throughout the Foc genome. The identified proteins were divided into 15 subgroups, majority of which (251, 63%) demonstrated the presence of the highly conserved C6 (CX2CX6CX6CX2CX6C) domain. Phylogenetic analysis clustered the Foc C6-type genes into 12 groups with 45% encoding for fungal specific transcription factors and 17% encoded proteins had a unique developmental specific DUF3468 DNA binding domain. In planta gene expression analysis revealed significant induced expression of a selective group of Foc C6-type genes from group IV and VII. The induced C6-type genes were predicted to be paralogous to the virulence regulatory genes (FTF1 and FTF2) of Fusarium oxysporum. Overall, our study provide a comprehensive information on the genome organization and expression profile of the C6-type gene family in Foc which would form the basis for further analyzing their potential role in regulating pathogenicity to onion by controlling the effector expression in Foc.

Regulators unite to enable plant entry.

A complex network of fungal transcription factors regulates plant invasion by Magnaporthe oryzae.

Genome-Wide Identification of Zn2Cys6 Class Fungal-Specific Transcription Factors (ZnFTFs) and Functional Analysis of UvZnFTF1 in Ustilaginoidea virens

Transcription factors (TFs) orchestrate the regulation of cellular gene expression and thereby determine cell functionality. In this study, we analyzed the distribution of TFs containing domains, which named as ZnFTFs, both in ascomycete and basidiomycete fungi. We found that ZnFTFs were widely distributed in these fungal species, but there was more expansion of the ZnFTF class in Ascomycota than Basidiomycota. We identified 40 ZnFTFs in Ustilaginoidea virens, and demonstrated the involvement of UvZnFTF1 in vegetative growth, conidiation, pigment biosynthesis and pathogenicity. RNA-Seq analysis suggested that UvZnFTF1 may regulate different nutrient metabolism pathways, the production of secondary metabolites, and the expression of pathogen-host interaction genes and secreted protein- encoding genes. Analysis of the distribution of different fungal TFs in U. virens further demonstrated that UvZnFTFs make up a large TF family and may play essential biological roles in U. virens.