Near complete assembly of Pyricularia penniseti infecting Cenchrus grass identified its eight core chromosomes.

Fungi from the Pyricularia genus cause blast disease in many economically important crops and grasses, such as wheat, rice, and Cenchrus grass JUJUNCAO. Structure variation associated with the gain and loss of effectors contributes largely to the adaptive evolution of this fungus towards diverse host plants. A telomere-to-telomere genome assembly would facilitate the identification of genome-wide structural variations through comparative genomics. Here, we report a telomere-to-telomere, near-complete genome assembly of a Pyricularia penniseti isolate JC-1 infecting JUJUNCAO. The assembly consists of eight core chromosomes and two supernumerary chromosomes, named mini1 and mini2, spanning 42.1 Mb. We annotated 12,156 protein-coding genes and identified 4.54% of the genome as repetitive sequences. The two supernumerary chromosomes contained fewer genes and more repetitive sequences than the core chromosomes. Our genome and results provide valuable resources for the future study in genome evolution, structure variation and host adaptation of the Pyricularia fungus.

BW312 Hordeum vulgare semi-dwarf mutant exhibits a shifted metabolic profile towards pathogen resistance.

INTRODUCTION: Plant hormonal mutants, which do not produce or are insensitive to hormones, are often affected in their growth and development, but other metabolic rearrangements might be involved. A trade-off between growth and stress response is necessary for the plant survival. OBJECTIVES: Here, we explore the metabolic profile and the pathogen resistance of a brassinosteroid-insensitive Hordeum vulgare L. semi-dwarf mutant, BW312. METHODS: We investigate BW312 metabolism through a chemical enrichment analysis, confirming a shifted metabolic profile towards pathogen resistance. The effective pathogen resistance of the mutant was tested in presence of Pyrenophora teres and Fusarium graminearum. RESULTS: Four compound families were increased in the mutant (pyrrolidines, basic amino acids, alkaloids, monounsaturated fatty acids), while two compound families were decreased (pyrrolidinones, anthocyanins). Dipeptides were also altered (increased and decreased). BW312 displayed a better resistance to Pyrenophora teres in the earliest stage of infection with a 21.5% decrease of the lesion length 10 days after infection. BW312 also exhibited a reduced lesion length (43.3%) and a reduced browning of the lesions (55.5%) when exposed to Fusarium graminearum at the seedling stage. CONCLUSION: The observed metabolomic shift strongly suggests that the BW312 semi-dwarf mutant is in a primed state, resulting in a standby state of alertness to pathogens.

Morpho-molecular characterization of phoma-like fungi from Morus alba in northern Thailand; a novel species (Boeremia albae) and a new host record (B. maritima).

Boeremia was established to accommodate phoma-resembling fungi. Its species occur in terrestrial ecosystems as endophytes, saprobes and pathogens, except one species reported from a marine ecosystem. Boeremia species are characterized by hyaline, thin-walled, and aseptate (occasionally 1(-2)-septate) conidia that are variable in shape, and hyaline, straight or slightly curved, thick-walled, and 1-septate ascospores that are usually constricted at the septum. In the past, host associations were used to delimit Boeremia species. However, since Boeremia taxa have overlapping morphological characters and are cryptic, it renders taxonomic identification arduous. Therefore, the use of other approaches including multi-gene phylogenetic analyses are imperative. Recommended DNA markers for species delineation are the internal transcribed spacer (ITS, nuclear rDNA consisting of ITS1-5.8S-ITS2) and large subunit (28S, D1-D2 domains of nuclear 28S rDNA) loci, and the genes for actin (ACT1), beta-tubulin (TBB1), RNA polymerase 2 (RPB2) and translation elongation factor 1α (TEF1). Here, we applied morphological and molecular phylogenetic analyses to establish a new taxon (B. albae), and a new host and geographical record for B. maritima associated with leaf spots of Morus alba (Moraceae) in northern Thailand. By providing sequence data for three additional gene regions, our phylogenetic analyses impart a stable phylogenetic placement of the ex-type strain of B. maritima, as illustrated. This is the first study that reports Boeremia species from M. alba, and B. maritima from a terrestrial habitat.

Deciphering the salt induced morphogenesis and functional potentials of Hortaea werneckii; a black pigmented halotolerant yeast isolated from solar saltern.

An intense black pigmented halotolerant yeast GUBPC1, was obtained from the solar salterns of Nerul, Goa-India. The isolate could tolerate 0 to 20 % NaCl. FE-SEM analysis revealed its polymorphic nature, exhibiting oval cells at higher salt concentrations and filamentous spindle like shapes at lower concentrations. Initially, the cells appear oval, yeast like in shape but gradually after 15 days of incubation, it becomes elongated and undergoes budding, exhibiting various budding patterns, from single polar bud to bipolar buds with annellidic ring, to lateral buds and eventually forming filamentous hyphae. The intracellular black pigment was identified as melanin based on ultraviolet-visible spectroscopy analysis. The molecular identification of the culture showed closest similarity with Hortaea werneckii. Plant polymer-degrading enzymatic activities such as cellulase, laccase, chitinase, xylanase, pectinase, amylase and protease were exhibited by the isolate GUBPC1. To further understand and explore its biotechnological potential, we performed whole-genome sequencing and analysis. The obtained genome size was 26.93 Mb with 686 contigs and a GC content of 53.24 %. We identified 9383 protein-coding genes, and their functional annotation revealed the presence of 435 CAZyme genes and 16 functional genes involved in secondary metabolite synthesis, thus providing a basis for its potential value in various biotechnological applications.

Virulence variation and pathotypes of Zymoseptoria tritici isolates causing wheat leaf blotch in Oromia, Ethiopia.

Leaf blotch, caused by Zymoseptoria tritici, is a fungal disease that poses a severe threat to wheat production worldwide. Knowledge of virulence variability is crucial in choosing effective control measures. However, there have only been a few studies of the pathogenic variability and pathotypes within Ethiopian isolates. Hence, the objective of this study was to assess the virulence spectrum and variability of Z. tritici isolates. Forty-three isolates were tested for their virulence and pathotype against 7 wheat differential lines that have different resistance genes. A pathogenicity assay detected 41 differential line-specific virulent isolates among 301 interactions between a host and pathogen based on the percentage coverage of the leaf area by pycnidia. Some isolates were virulent against 50 %-60 % of the resistant genes, but most of them were virulent against some differential lines. Isolates such as EtA-11, EtSh-1, EtSh-2, EtSh-4, and EtA-19 expressed broad-spectrum virulence, highlighting that such isolates are useful for germplasm screening. The isolates were classified into 25 pathotypes, defined by their differential virulence responses. They were also assigned to two clusters according to their mean pycnidia percent. Pathotypes and principal component analysis detected 58.1 % and 62.2 % pathogenic diversity in Ethiopian isolates, respectively. The current findings provide information that breeders can use to identify and select more resistant varieties for farmers.

The yeast Dothiora sorbi IOJ-3 naturally produced various filamentous sectors with distinct abilities by undergoing DNA demethylation.

Some fungi have demonstrated the ability to adapt rapidly to changing environments by exhibiting morphological plasticity, a trait influenced by species and environmental factors. Here, an anamorphic yeast strain IOJ-3 exhibited unique sectorization characteristics, naturally producing diverse filamentous sectors when cultivated on potato dextrose agar (PDA) medium or natural culture medium for durations exceeding 13 days. The strain IOJ-3 and its filamentous sectors were identified as Dothiora sorbi. The morphology of the sectors was consistent and heritable. The life cycle of strain IOJ-3 was investigated through microscopic observation, emphasizing the development of conidiogenous cells as a crucial stage, from which filamentous sectors originate. Some physiological characteristics of IOJ-3 and filamentous sectors are compared, and strain IOJ-3 has a higher antibiotic tolerance than two filamentous sectors, IOJ-3a expands faster on the culture medium, and IOJ-3b can penetrate cellophane. A transcriptomic analysis was conducted to investigate the differentially expressed genes between the yeast form IOJ-3 and its two filamentous sectors, revealing a total of 594 genes that exhibited consistent differential expression relative to IOJ-3, including 44 silencing genes in IOJ-3 that were activated. Gene Ontology analysis indicated that these differentially expressed genes were primarily associated with the cellular component category. Furthermore, adding 5-Azacytidine accelerated filamentous sectorization and increased the proportion of filamentous cells of strain IOJ-3 in PD liquid media, suggesting that the filamentous sectorization observed in strain IOJ-3 is linked to processes of DNA demethylation. In conclusion, this study sheds light on the biological characteristics of D. sorbi regarding morphological transitions and provides substantial direction for exploring genes related to fungal filamentous development.

Genome-wide differentiation corresponds to climatic niches in two species of lichen-forming fungi.

Lichens can withstand fluctuating environmental conditions such as hydration-desiccation cycles. Many species distribute across climate zones, suggesting population-level adaptations to conditions such as freezing and drought. Here, we aim to understand how climate affects population genomic patterns in lichenized fungi. We analysed population structure along elevational gradients in closely related Umbilicaria phaea (North American; two gradients) and Umbilicaria pustulata (European; three gradients). All gradients showed clear genomic breaks splitting populations into low-elevation (Mediterranean zone) and high-elevation (cold temperate zone). A total of 3301 SNPs in U. phaea and 138 SNPs in U. pustulata were driven to fixation between the two ends of the gradients. The difference between the species is likely due to differences in recombination rate: the sexually reproducing U. phaea has a higher recombination rate than the primarily asexually reproducing U. pustulata. Cline analysis revealed allele frequency transitions along all gradients at approximately 0°C, coinciding with the transition between the Mediterranean and cold temperate zones, suggesting freezing is a strong driver of population differentiation. Genomic scans further confirmed temperature-related selection targets. Both species showed similar differentiation patterns overall, but different selected alleles indicate convergent adaptation to freezing. Our results enrich our knowledge of fungal genomic functions related to temperature and climate, fungal population genomics, and species responses to environmental heterogeneity.

An array of Zymoseptoria tritici effectors suppress plant immune responses.

Zymoseptoria tritici is the most economically significant fungal pathogen of wheat in Europe. However, despite the importance of this pathogen, the molecular interactions between pathogen and host during infection are not well understood. Herein, we describe the use of two libraries of cloned Z. tritici effectors that were screened to identify effector candidates with putative pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI)-suppressing activity. The effectors from each library were transiently expressed in Nicotiana benthamiana, and expressing leaves were treated with bacterial or fungal PAMPs to assess the effectors' ability to suppress reactive oxygen species (ROS) production. From these screens, numerous effectors were identified with PTI-suppressing activity. In addition, some effectors were able to suppress cell death responses induced by other Z. tritici secreted proteins. We used structural prediction tools to predict the putative structures of all of the Z. tritici effectors and used these predictions to examine whether there was enrichment of specific structural signatures among the PTI-suppressing effectors. From among the libraries, multiple members of the killer protein-like 4 (KP4) and killer protein-like 6 (KP6) effector families were identified as PTI suppressors. This observation is intriguing, as these protein families were previously associated with antimicrobial activity rather than virulence or host manipulation. This data provides mechanistic insight into immune suppression by Z. tritici during infection and suggests that, similar to biotrophic pathogens, this fungus relies on a battery of secreted effectors to suppress host immunity during early phases of colonization.

Amplification-free detection of Ascochyta blight in chickpea using a simple molecular beacon assay.

Ascochyta blight is a major biotic stress that limits chickpea production globally. Fungicide application remains one of the effective control measures for the endemic spread. Due to the serious threat that synthetic fungicides pose to crop quality, early diagnosis of the pathogen is imperative. Whilst there have previously been several conventional lab-based diagnostic methods developed for early detection of Ascochyta rabiei, they require long assay times, specialised equipment and facilities, and trained personnel to process the samples. To overcome this challenge, a rapid amplification-free detection assay using a molecular beacon probe was developed. The method consists of a simple assembly assay that accurately detects pathogen within 30 min. The developed assay is species-specific and has a similar sensitivity level as conventional amplification-based methods. Although it is still a lab-based technique, considering the simplicity of the assay, it has a great potential to be developed further as a reliable in-field diagnostic device for early detection and quantification of fungal pathogen spores.

Molecular characterization of a novel mycotombus­like virus isolated from the phytopathogenic fungus Nigrospora oryzae.

In this study, we identified a new mycotombus-like mycovirus from the phytopathogenic fungus Nigrospora oryzae, which was tentatively designated as "Nigrospora oryzae umbra-like virus 1" (NoULV1). The complete genome of NoULV1 is 3,381 nt long, containing two open reading frames (ORF1 and ORF2). ORF1 encodes a hypothetical protein with an unknown function, while ORF2 encodes an RNA-dependent RNA polymerase (RdRp) with a conserved RdRp domain containing a metal-binding 'GDN' triplet in motif C, which is distinct from the 'GDD' motif found in most + ssRNA mycoviruses. A homology search revealed that the RdRp encoded by ORF2 was similar to the RdRp of umbra-like mycoviruses. Phylogenetic analysis based on the RdRp indicated that NoULV1 was grouped into a clade together with umbra-like mycoviruses belonging to the proposed family "Mycotombusviridae".

Nematicidal and Insecticidal Compounds from the Laurel Forest Endophytic Fungus Phyllosticta sp.

The search for natural product-based biopesticides from endophytic fungi is an effective tool to find new solutions. In this study, we studied a pre-selected fungal endophyte, isolate YCC4, from the paleoendemism Persea indica, along with compounds present in the extract and the identification of the insect antifeedant and nematicidal ones. The endophyte YCC4 was identified as Phyllosticta sp. by molecular analysis. The insect antifeedant activity was tested by choice bioassays against Spodoptera littoralis, Myzus persicae, and Rhopalosiphum padi, and the in vitro and in vivo mortality was tested against the root-knot nematode Meloidogyne javanica. Since the extract was an effective insect antifeedant, a strong nematicidal, and lacked phytotoxicity on tomato plants, a comprehensive chemical study was carried out. Two new metabolites, metguignardic acid (4) and (-)-epi-guignardone I (14), were identified along the known dioxolanones guignardic acid (1), ethyl guignardate (3), guignardianones A (5), C (2), D (7), and E (6), phenguignardic acid methyl ester (8), the meroterpenes guignardone A (9) and B (10), guignarenone B (11) and C (12), (-)-guignardone I (13), and phyllomeroterpenoid B (15). Among these compounds, 1 and 4 were effective antifeedants against S. littoralis and M. persicae, while 2 was only active on the aphid M. persicae. The nematicidal compounds were 4, 7, and 8. This is the first report on the insect antifeedant or nematicidal effects of these dioxolanone-type compounds. Since the insect antifeedant and nematicidal activity of the Phyllosticta sp. extract depend on the presence of dioxolanone components, future fermentation optimizations are needed to promote the biosynthesis of these compounds instead of meroterpenes.

Secondary Metabolites from Australian Lichens Ramalina celastri and Stereocaulon ramulosum Affect Growth and Metabolism of Photobiont Asterochloris erici through Allelopathy.

In the present work, the phytotoxic effects of secondary metabolites extracted from lichen Ramalina celastri (usnic acid) and lichen Stereocaulon ramulosum (a naturally occurring mixture of atranorin and perlatolic acid, approx. 3:1) on cultures of the aposymbiotically grown lichen photobiont Asterochloris erici were evaluated. Algae were cultivated on the surface of glass microfiber disks with applied crystals of lichen extracts for 14 days. The toxicity of each extract was tested at the two selected doses in quantities of 0.01 mg/disk and 0.1 mg/disk. Cytotoxicity of lichen extracts was assessed using selected physiological parameters, such as growth (biomass production) of photobiont cultures, content of soluble proteins, chlorophyll a fluorescence, chlorophyll a integrity, contents of chlorophylls and total carotenoids, hydrogen peroxide, superoxide anion, TBARS, ascorbic acid (AsA), reduced (GSH) and oxidized (GSSG) glutathione, and composition of selected organic acids of the Krebs cycle. The application of both tested metabolic extracts decreased the growth of photobiont cells in a dose-dependent manner; however, a mixture of atranorin and perlatolic acid was more effective when compared to usnic acid at the same dose tested. A higher degree of cytotoxicity of extracts from lichen S. ramulosum when compared to identical doses of extracts from lichen R. celastri was also confirmed by a more pronounced decrease in chlorophyll a fluorescence and chlorophyll a integrity, decreased content of chlorophylls and total carotenoids, increased production of hydrogen peroxide and superoxide anion, peroxidation of membrane lipids (assessed as TBARS), and a strong decrease in non-enzymatic antioxidants such as AsA, GSH, and GSSG. The cytotoxicity of lichen compounds was confirmed by a strong alteration in the composition of selected organic acids included in the Krebs cycle. The increased ratio between pyruvic acid and citric acid was a very sensitive parameter of phytotoxicity of lichen secondary metabolites to the algal partner of symbiosis. Secondary metabolites of lichens are potent allelochemicals and play significant roles in maintaining the balance between mycobionts and photobionts, forming lichen thallus.

Molecular characterization of a novel fusarivirus infecting the plant-pathogenic fungus Nigrospora sphaerica.

Here, we describe a novel mycovirus, tentatively designated as "Nigrospora sphaerica fusarivirus 2" (NsFV2), which was isolated from the phytopathogenic fungus Nigrospora sphaerica strain HNXX-Ns20. NsFV2 has a single-stranded positive-sense RNA (+ ssRNA) genome of 6,156 nucleotides, excluding the poly(A) tail, and contains two putative open reading frames (ORFs). ORF1 encodes a large polypeptide of 1,509 amino acids (aa) containing a conserved RNA-dependent RNA polymerase (RdRp) domain and a viral helicase domain. The ORF1-encoded polypeptide shares 29.40-68.48% sequence identity with other fusariviruses and shares the highest sequence identity (68.48%) with Nigrospora sphaerica fusarivirus 1 (NsFV1). The small ORF2 encodes a polypeptide of 483 aa that contains a conserved chromosome segregation ATPase (Smc) domain. Multiple sequence alignments and phylogenetic analysis based on the ORF1-encoded polypeptide indicated that NsFV2 should be considered a new member of the genus Alphafusarivirus of the family Fusariviridae.

Bacillus australimaris protect Gloriosa superba L. against Alternaria alternata infestation.

Gloriosa superba L., a medicinally important plant, is often affected by leaf blight disease caused by Alternaria alternata, which compromises its productivity. This study explores the protective effects of Bacillus australimaris endophyte (NBRI GS34), demonstrating that its inoculation not only inhibits the disease but also promotes plant growth and increases the concentrations of bioactive metabolites. Co-culturing NBRI GS34 with A. alternata significantly boosts protease (30-50%) and chitinase (6-28%) activities, evidencing a synergistic interaction. Scanning electron microscopy and GC-MS analysis confirm NBRI GS34's antagonistic action and reveal antifungal compounds like undecanoic acid and benzene carboxylic acid in treatments. Greenhouse experiments show a 78% reduction in disease incidence with NBRI GS34 treatment, enhancing vegetative growth and upregulating defense-related genes. Additionally, HPLC analysis reveals increased gloriosine and colchicine concentrations by 52% and 33%, respectively. These findings suggest NBRI GS34 could serve as a sustainable fungicide alternative, enhancing the production of medically valuable compounds and highlighting its potential pharmaceutical applications.

Magnolol from Magnolia officinalis inhibits Neopestalotiopsis ellipsospora by damaging the cell membrane.

Tea gray blight disease is a significant threat to the tea industry. In this study, a biological activity approach was utilized to investigate the efficacy of green fungicides from Magnolia officinalis stem bark against Neopestalotiopsis ellipsospora. The active compounds were isolated and purified, and their structures were elucidated. In vitro and in vivo activity screenings revealed that the n-hexane extract, which contained magnolol and honokiol, exhibited strong activity against N. ellipsospora, showing complete inhibition at 100 mg/L. The EC50 values of magnolol and honokiol were 5.11 and 6.09 mg/L, respectively. Mechanistically, magnolol was found to disrupt N. ellipsospora invasion by damaging the cell membrane, increasing permeability, and causing leakage of intracellular substances. Transcriptome analysis revealed that magnolol treatment downregulates membrane-related genes and leads to the enrichment of lipid metabolism pathway genes. This study revealed that magnolol inhibits N. ellipsospora growth by affecting lipid metabolism and compromising cell membrane integrity.

Rhodopseudomonas palustris Atp2 Protein Exerts Antifungal Effects by Targeting the Ribosomal Protein MoRpl12 in Magnaporthe oryzae.

Rice blast is one of the most hazardous diseases affecting rice production. Previously, we discovered that the Atp2 protein of Rhodopseudomonas palustris could significantly inhibit the appressorium formation and pathogenicity of Magnaporthe oryzae. However, the molecular mechanism of this fungus has remained unknown. This study revealed that Atp2 can enter the cell and interact with the ribosomal protein MoRpl12 of M. oryzae, directly affecting the expression of the MoRpl12 protein. Silencing the MoRPL12 gene can affect cell wall integrity, growth, conidiogenesis, and fungal pathogenicity. The quantitative reverse transcription PCR results showed significant changes in the expression of conidiation-related genes in the MoRPL12 gene-silenced mutants or in the Atp2 protein-treated plants. We further found that Atp2 treatment can influence the expression of ribosomal-related genes, such as RPL, in M. oryzae. Our study revealed a novel antifungal mechanism by which the Atp2 protein binds to the ribosomal protein MoRpl12 and inhibits the pathogenicity of rice blast fungus, providing a new potential target for rice blast prevention and control.

Biocontrol mechanisms of poplar leaf blight due to Nigrospora oryzae.

Nigrospora oryzae, a newly identified pathogen, is responsible for poplar leaf blight, causing significant harm to poplar growth. Here, we describe, for the first time, a biological control method for the control of poplar leaf blight via the applications of 3 dominant Trichoderma strains/species. In this study, dominant Trichoderma species/strains with the potential for biocontrol were identified and then further characterised via dual culture assays, volatile organic compounds (VOCs), and culture filtrates. The biocontrol efficacy of these strains against N. oryzae was found to exceed 60%. Furthermore, the reactive oxygen species (ROS) content in Populus davidiana × P. alba var. pyramidalis (PdPap) leaves pretreated with these Trichoderma strains significantly decreased. Furthermore, pretreatment of PdPap with a combination of these Trichoderma (Tcom) resulted in 9.71-fold and 1.95-fold increases in peroxidase (POD) and superoxide dismutase (SOD) activity, respectively, and 3.87-fold decrease in the MDA content compared to controls. Moreover, Tcom pretreatment activated the salicylic acid (SA) and jasmonic acid (JA) pathway-dependent defence responses of poplar, upregulating pathogenesis-related protein (PR) and MYC proto-oncogene (MYC-R) by more than 12-fold and 17.32-fold, respectively. In addition, Trichoderma treatments significantly increased the number of lateral roots, aboveground biomass, and stomata number and density of PdPap, and Tcom was superior to the single pretreatments. The soil pH also became weakly acidic in these pretreatments, which is beneficial for the growth of PdPap seedlings. These findings indicate that these dominant Trichoderma strains can effectively increase biocontrol and poplar growth promotion.

Functional characterization of extracellular and intracellular catalase-peroxidases involved in virulence of the fungal wheat pathogen Zymoseptoria tritici.

Understanding how pathogens defend themselves against host defence mechanisms, such as hydrogen peroxide (H2O2) production, is crucial for comprehending fungal infections. H2O2 poses a significant threat to invading fungi due to its potent oxidizing properties. Our research focuses on the hemibiotrophic fungal wheat pathogen Zymoseptoria tritici, enabling us to investigate host-pathogen interactions. We examined two catalase-peroxidase (CP) genes, ZtCpx1 and ZtCpx2, to elucidate how Z. tritici deals with host-generated H2O2 during infection. Our analysis revealed that ZtCpx1 was up-regulated during biotrophic growth and asexual spore formation in vitro, while ZtCpx2 showed increased expression during the transition from biotrophic to necrotrophic growth and in-vitro vegetative growth. Deleting ZtCpx1 increased the mutant's sensitivity to exogenously added H2O2 and significantly reduced virulence, as evidenced by decreased Septoria tritici blotch symptom severity and fungal biomass production. Reintroducing the wild-type ZtCpx1 allele with its native promoter into the mutant strain restored the observed phenotypes. While ZtCpx2 was not essential for full virulence, the ZtCpx2 mutants exhibited reduced fungal biomass development during the transition from biotrophic to necrotrophic growth. Moreover, both CP genes act synergistically, as the double knock-out mutant displayed a more pronounced reduced virulence compared to ΔZtCpx1. Microscopic analysis using fluorescent proteins revealed that ZtCpx1 was localized in the peroxisome, indicating its potential role in managing host-generated reactive oxygen species during infection. In conclusion, our research sheds light on the crucial roles of CP genes ZtCpx1 and ZtCpx2 in the defence mechanism of Z. tritici against host-generated hydrogen peroxide.

Physiological and molecular responses of a resistant and susceptible wheat cultivar to the fungal wheat pathogen Zymoseptoria tritici.

Zymoseptoria tritici is the causal agent of Septoria tritici blotch (STB), one of the most economically destructive wheat foliar diseases. In this study, we explore the physiological and molecular changes elicited in two wheat cultivars with divergent responses (Taichung 29 = susceptible, and Shafir = resistant) upon infection by Z. tritici. Our aim is to uncover novel insights into the intricate mechanisms that govern wheat defense against Z. tritici infection. Our quantitative histopathological study showed that H2O2 accumulated in the resistant cultivar to a higher degree compared to the susceptible cultivar at the biotrophic and switching phase. Additionally, we combined qPCR with a targeted quantitative HPLC technique to evaluate the expression profiles of 13 defense-related genes and profile the polyphenolic compounds induced differentially in the STB susceptible and resistant cultivar. Our finding indicated that five out of 13 genes were strongly up-regulated in the resistant cultivar compared with that of the susceptible one at eight days post-inoculation (dpi), corresponding to the transition phase present in the infection process of Z. tritici. Finally, our targeted HPLC analysis demonstrated that the traced phenolic compounds were highly elevated in the susceptible cultivar infected by Z. tritici compared with that of the resistant cultivar. In conclusion, our comprehensive analysis unveils a robust defense response in the resistant wheat cultivar Shafir, characterized by heightened H2O2 accumulation, significant up-regulation of key defense-related genes during the transition phase, and a distinct profile of polyphenolic compounds, shedding light on the intricate mechanisms contributing to its resistance against Z. tritici, thereby providing valuable insights for the development of more resilient wheat varieties.

Cyanobacteria-Fungi Co-Cultures: Which Partner Contributes to Antifungal Activity?

Cyanobacteria synthesize secondary metabolites with antifungal activity, making them potential biopesticide agents for sustainable, eco-friendly agriculture. Programmes to identify Cyanobacterial strains with effective bioactivity generally screen strains maintained in culture collections. These strains are often monoclonal but non-axenic and this may potentially influence the bioactivity of the generated biomass. The present study investigated in vitro antifungal activity of Nostoc muscorum MACC-189 and N. linckia MACC-612 strains co-isolated with fungal co-partners and maintained in the Mosonmagyaróvár Algal Culture Collection (MACC). The fungal co-partners were isolated from the Cyanobacterial stock cultures and identified as Purpureocillium lilacinum and Sarocladium sp., respectively. The cultures were tested against seven phytopathogens. The phytopathogenic fungi were grown on potato dextrose agar plates and suspension cultures of the Cyanobacteria-fungi and isolated fungal co-partners were placed in the centre of the plate. Antifungal effects were assessed semi-quantitatively after 10 days of incubation. The Cyanobacteria-fungal co-cultures had antifungal activity against Monilinia fructigena and Aspergillus sp. with the N. muscorum/P. lilacinum culture being the most effective. The fungal isolates inhibited M. fructigena with P. lilacinum having a dose-dependent response but did not inhibit Aspergillus sp. This suggested that the antifungal effect of the Cyanobacterial cultures on M. fructigena was due to the fungal partner rather than the cyanobacterium while the antifungal effect on Aspergillus sp. was due to the cyanobacterium partner. As it was not possible to maintain living axenic N. muscorum and N. linckia cultures, this could not be conclusively confirmed. These results highlight the importance of either using axenic cultures or identifying the co-isolates when testing Cyanobacteria cultures for antifungal bioactivity.