FgPfn participates in vegetative growth, sexual reproduction, pathogenicity, and fungicides sensitivity via affecting both microtubules and actin in the filamentous fungus Fusarium graminearum.

Fusarium head blight (FHB), caused by Fusarium graminearum species complexes (FGSG), is an epidemic disease in wheat and poses a serious threat to wheat production and security worldwide. Profilins are a class of actin-binding proteins that participate in actin depolymerization. However, the roles of profilins in plant fungal pathogens remain largely unexplored. Here, we identified FgPfn, a homolog to profilins in F. graminearum, and the deletion of FgPfn resulted in severe defects in mycelial growth, conidia production, and pathogenicity, accompanied by marked disruptions in toxisomes formation and deoxynivalenol (DON) transport, while sexual development was aborted. Additionally, FgPfn interacted with Fgα1 and Fgß2, the significant components of microtubules. The organization of microtubules in the ΔFgPfn was strongly inhibited under the treatment of 0.4 µg/mL carbendazim, a well-known group of tubulin interferers, resulting in increased sensitivity to carbendazim. Moreover, FgPfn interacted with both myosin-5 (FgMyo5) and actin (FgAct), the targets of the fungicide phenamacril, and these interactions were reduced after phenamacril treatment. The deletion of FgPfn disrupted the normal organization of FgMyo5 and FgAct cytoskeleton, weakened the interaction between FgMyo5 and FgAct, and resulting in increased sensitivity to phenamacril. The core region of the interaction between FgPfn and FgAct was investigated, revealing that the integrity of both proteins was necessary for their interaction. Furthermore, mutations in R72, R77, R86, G91, I101, A112, G113, and D124 caused the non-interaction between FgPfn and FgAct. The R86K, I101E, and D124E mutants in FgPfn resulted in severe defects in actin organization, development, and pathogenicity. Taken together, this study revealed the role of FgPfn-dependent cytoskeleton in development, DON production and transport, fungicides sensitivity in F. graminearum.

Mitochondrial Outer Membrane Translocase MoTom20 Modulates Mitochondrial Morphology and Is Important for Infectious Growth of the Rice Blast Fungus Magnaporthe oryzae.

Mitochondria are highly dynamic organelles that constantly change their morphology to adapt to the cellular environment through fission and fusion, which is critical for a cell to maintain normal cellular functions. Despite the significance of this process in the development and pathogenicity of the rice blast fungus Magnaporthe oryzae, the underlying mechanism remains largely elusive. Here, we identified and characterized a mitochondrial outer membrane translocase, MoTom20, in M. oryzae. Targeted gene deletion revealed that MoTom20 plays an important role in vegetative growth, conidiogenesis, penetration, and infectious growth of M. oryzae. The growth rate, conidial production, appressorium turgor, and pathogenicity are decreased in the ΔMotom20 mutant compared with the wild-type and complemented strains. Further analysis revealed that MoTom20 localizes in mitochondrion and plays a key role in regulating mitochondrial fission and fusion balance, which is critical for infectious growth. Finally, we found that MoTom20 is involved in fatty-acid utilization, and its yeast homolog ScTom20 is able to rescue the defects of ΔMotom20 in mitochondrial morphology and pathogenicity. Overall, our data demonstrate that MoTom20 is a key regulator for mitochondrial morphology maintenance, which is important for infectious growth of the rice blast fungus M. oryzae. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Myo5B plays a significant role in the hyphal growth and virulence of the human pathogenic fungus Mucor lusitanicus.

Mucormycosis is an emerging and deadly invasive fungal infection caused by fungi belonging to the Mucorales order. We investigated the myosin superfamily, which encompasses diverse actin-based motor proteins with various cellular functions. Specifically, the role of the Myo5B (ID 179665) protein from the myosin class V family in Mucor lusitanicus was explored by generating silencing phenotypes and null mutants corresponding to the myo5B gene. Silencing fungal transformants exhibited a markedly reduced growth rate and a nearly complete absence of sporulation compared to the wild-type strain. The myo5BΔ null mutant strain displayed atypical characteristics, including abnormally short septa and inflated hyphae. Notably, there were a majority of small yeast-like cells instead of filamentous hyphae in the mutant. These yeast-like cells cannot germinate normally, resulting in a loss of polarity. In vivo virulence assays conducted in the Galleria mellonella invertebrate model revealed that the myo5BΔ mutant strain was avirulent. These findings shed light on the crucial contributions of the Myo5B protein to the dimorphism and pathogenicity of M. lusitanicus. Therefore, the myosin V family is a potential target for future therapeutic interventions aimed at treating mucormycosis.

Identification of two genes essential for basidiospore formation during the postmeiotic stages in Pleurotus ostreatus.

A sporeless strain is an important breeding target in the mushroom industry. However, basidiospore production in the oyster mushroom Pleurotus ostreatus has been shown to be impaired by single-gene mutations in only two meiosis-related genes, mer3 and msh4. This study proposed a strategy for identifying the genes essential for basidiospore formation after meiotic division to determine new targets for molecular breeding. RNA-seq analysis was performed to identify P. ostreatus genes that are specifically expressed in the gill tissue of fruiting bodies, where basidiospore formation occurs. Transcriptome data during fruiting development of Coprinopsis cinerea, in which the meiotic steps progress synchronously, were then used to identify genes that are active in the postmeiotic stages. Based on these comparative analyses, five P. ostreatus genes were identified. Plasmids containing expression cassettes for hygromycin B-resistance screening, Cas9, and single-guide RNA targeting each gene were introduced into the protoplasts of dikaryotic strain, PC9×#64, to generate dikaryotic gene disruptants. Among the obtained transformants, three dikaryotic pcl1 disruptants and two cro6c disruptants did not produce basidiospores. Microscopic analyses indicated that spore formation was arrested at particular stages in these gene disruptants. These results indicate that these two genes are essential for mature spore formation in this fungus.

The pleiotropic phenotype of FlbA of Aspergillus niger is explained in part by the activity of seven of its downstream-regulated transcription factors.

Inactivation of flbA in Aspergillus niger results in thinner cell walls, increased cell lysis, abolished sporulation, and an increased secretome complexity. A total of 36 transcription factor (TF) genes are differentially expressed in ΔflbA. Here, seven of these genes (abaA, aslA, aslB, azf1, htfA, nosA, and srbA) were inactivated. Inactivation of each of these genes affected sporulation and, with the exception of abaA, cell wall integrity and protein secretion. The impact on secretion was strongest in the case of ΔaslA and ΔaslB that showed increased pepsin, cellulase, and amylase activity. Biomass was reduced of agar cultures of ΔabaA, ΔaslA, ΔnosA, and ΔsrbA, while biomass was higher in liquid shaken cultures of ΔaslA and ΔaslB. The ΔaslA and ΔhtfA strains showed increased resistance to H2O2, while ΔaslB was more sensitive to this reactive oxygen species. Together, inactivation of the seven TF genes impacted biomass formation, sporulation, protein secretion, and stress resistance, and thereby these genes explain at least part of the pleiotropic phenotype of ΔflbA of A. niger.

Characterization of linoleate dioxygenases in basidiomycetes and the functional role of CcLdo1 in regulating fruiting body development in Coprinopsis cinerea.

Coprinopsis cinerea, a model fungus, is utilized for investigating the developmental mechanisms of basidiomycetes. The development of basidiomycetes is a highly organized process that requires coordination among genetic, environmental, and physiological factors. Oxylipins, a class of widely distributed signaling molecules, play crucial roles in fungal biology. Among oxylipins, the sexual pheromone-inducing factors (psi factors) have been identified as key regulators of the balance between asexual and sexual spore development in Ascomycetes. Linoleate dioxygenases are enzymes involved in the biosynthesis of psi factors, yet their specific physiological functions in basidiomycete development remain unclear. In this study, linoleate dioxygenases in basidiomycetes were identified and characterized. Phylogenetic analysis revealed that linoleate dioxygenases from Basidiomycota formed a distinct clade, with linoleate dioxygenases from Agaricomycetes segregating into three groups and those from Ustilaginomycetes forming a separate group. Both basidiomycete and ascomycete linoleate dioxygenases shared two characteristic domains: the N-terminal of linoleate dioxygenase domain and the C-terminal of cytochrome P450 domain. While the linoleate dioxygenase domains exhibited similarity between basidiomycetes and ascomycetes, the cytochrome P450 domains displayed high diversity in key sites. Furthermore, the gene encoding the linoleate dioxygenase Ccldo1 in C. cinerea was knocked out, resulting in a significant increase in fruiting body formation without affecting asexual conidia production. This observation suggests that secondary metabolites synthesized by CcLdo1 negatively regulate the sexual reproduction process in C. cinerea while not influencing the asexual reproductive process. This study represents the first identification of a gene involved in secondary metabolite synthesis that regulates basidiocarp development in a basidiomycete.

pSPObooster: A Plasmid System to Improve Sporulation Efficiency of Saccharomyces cerevisiae Lab Strains.

Common Saccharomyces cerevisiae lab yeast strains derived from S288C have meiotic defects and therefore are poor sporulators. Here, we developed a plasmid system containing corrected alleles of the MKT1 and RME1 genes to rescue the meiotic defects and show that standard BY4741 and BY4742 strains containing the plasmid display faster and more efficient sporulation. The plasmid, pSPObooster, can be maintained as an episome and easily cured or stably integrated into the genome at a single locus. We demonstrate the use of pSPObooster in low- and high-throughput yeast genetic manipulations and show that it can expedite both procedures without impacting strain behavior.

The MAPK homolog, Smk1, promotes assembly of the glucan layer of the spore wall in S. cerevisiae.

Smk1 is a MAPK homolog in the yeast Saccharomyces cerevisiae that controls the postmeiotic program of spore wall assembly. During this program, haploid cells are surrounded by a layer of mannan and then a layer of glucan. These inner layers of the spore wall resemble the vegetative cell wall. Next, the outer layers consisting of chitin/chitosan and then dityrosine are assembled. The outer layers are spore-specific and provide protection against environmental stressors. Smk1 is required for the proper assembly of spore walls. However, the protective properties of the outer layers have limited our understanding of how Smk1 controls this morphogenetic program. Mutants lacking the chitin deacetylases, Cda1 and Cda2, form spores that lack the outer layers of the spore wall. In this study, cda1,2∆ cells were used to demonstrate that Smk1 promotes deposition of the glucan layer of the spore wall through the partially redundant glucan synthases Gsc2 and Fks3. Although Gsc2 is localized to sites of spore wall assembly in the wild type, it is mislocalized in the mother cell cytoplasm in the smk1∆ mutant. These findings suggest that Smk1 controls assembly of the spore wall by regulating the localization of Gsc2 during sporogenesis.

Pathogen-microbiome interactions and the virulence of an entomopathogenic fungus.

Bacteria shape interactions between hosts and fungal pathogens. In some cases, bacteria associated with fungi are essential for pathogen virulence. In other systems, host-associated microbiomes confer resistance against fungal pathogens. We studied an aphid-specific entomopathogenic fungus called Pandora neoaphidis in the context of both host and pathogen microbiomes. Aphids host several species of heritable bacteria, some of which confer resistance against Pandora. We first found that spores that emerged from aphids that harbored protective bacteria were less virulent against subsequent hosts and did not grow on plate media. We then used 16S amplicon sequencing to study the bacterial microbiome of fungal mycelia and spores during plate culturing and host infection. We found that the bacterial community is remarkably stable in culture despite dramatic changes in pathogen virulence. Last, we used an experimentally transformed symbiont of aphids to show that Pandora can acquire host-associated bacteria during infection. Our results uncover new roles for bacteria in the dynamics of aphid-pathogen interactions and illustrate the importance of the broader microbiological context in studies of fungal pathogenesis. IMPORTANCE: Entomopathogenic fungi play important roles in the population dynamics of many insect species. Understanding the factors shaping entomopathogen virulence is critical for agricultural management and for the use of fungi in pest biocontrol. We show that heritable bacteria in aphids, which confer protection to their hosts against fungal entomopathogens, influence virulence against subsequent hosts. Aphids reproduce asexually and are typically surrounded by genetically identical offspring, and thus these effects likely shape the dynamics of fungal disease in aphid populations. Furthermore, fungal entomopathogens are known to rapidly lose virulence in lab culture, complicating their laboratory use. We show that this phenomenon is not driven by changes in the associated bacterial microbiome. These results contribute to our broader understanding of the aphid model system and shed light on the biology of the Entomophthorales-an important but understudied group of fungi.

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.

Inhibitory activity of bacterial lipopeptides against Fusarium oxysporum f.sp. Strigae.

This study investigated the influence of bacterial cyclic lipopeptides (LP; surfactins, iturins, fengycins) on microbial interactions. The objective was to investigate whether the presence of bacteria inhibits fungal growth and whether this inhibition is due to the release of bacterial metabolites, particularly LP. Selected endophytic bacterial strains with known plant-growth promoting potential were cultured in the presence of Fusarium oxysporum f.sp. strigae (Fos), which was applied as model fungal organism. The extracellular metabolome of tested bacteria, with a focus on LP, was characterized, and the inhibitory effect of bacterial LP on fungal growth was investigated. The results showed that Bacillus velezensis GB03 and FZB42, as well as B. subtilis BSn5 exhibited the strongest antagonism against Fos. Paraburkholderia phytofirmans PsJN, on the other hand, tended to have a slight, though non-significant growth promotion effect. Crude LP from strains GB03 and FZB42 had the strongest inhibitory effect on Fos, with a significant inhibition of spore germination and damage of the hyphal structure. Liquid chromatography tandem mass spectrometry revealed the production of several variants of iturin, fengycin, and surfactin LP families from strains GB03, FZB42, and BSn5, with varying intensity. Using plate cultures, bacillomycin D fractions were detected in higher abundance in strains GB03, FZB42, and BSn5 in the presence of Fos. Additionally, the presence of Fos in dual plate culture triggered an increase in bacillomycin D production from the Bacillus strains. The study demonstrated the potent antagonistic effect of certain Bacillus strains (i.e., GB03, FZB42, BSn5) on Fos development. Our findings emphasize the crucial role of microbial interactions in shaping the co-existence of microbial assemblages.

Antifungal activity of Serratia plymuthica against the phytopathogenic fungus Alternariatenuissima.

The antifungal activity of Serratia plymuthica CCGG2742, a bacterial strain isolated from grapes berries skin, against a phytopathogenic fungus isolated from blueberries was evaluated in vitro and in vivo. In order to characterize the wild fungal isolate, phylogenetic analysis using concatenated DNA sequences from the RPB2 and TEF1 genes and of the ITS region was performed, allowing the identification of the fungal isolate that was called Alternaria tenuissima CC17. Hyphae morphology, mycelium ultrastructure, conidia and reproductive structures were in agreement with the phylogenetic analysis. The antifungal activity of the S. plymuthica strain was dependent on the composition of the culture medium. The greatest inhibition of mycelial growth of A. tenuissima CC17 by S. plymuthica CCGG2742 was observed on YTS medium, which lacks of an easily assimilable carbon source. Fungal growth medium supplemented with 50 % of bacterial supernatant decreased the conidia germination of A. tenuissima CC17 up to 32 %. Preventive applications of S. plymuthica CCGG2742 to blueberries and tomato leaves at conidia:bacteria ratio of 1:100, protected in 77.8 ± 4.6 % and 98.2 ± 0.6 % to blueberries and tomato leaves from infection caused by A. tenuissima CC17, respectively. To the best of our knowledge, this is the first report on the antifungal activity of S. plymuthica against A. tenuissima, which could be used as a biological control agent of plant diseases caused by this fungal species. In addition, the results of this work could be a starting point to attribute the real importance of A. tenuissima as a pathogen of blueberries in Chile, which until now had been considered almost exclusively to A. alternata. Likewise, this research could be relevant to start developing highly effective strategies based on S. plymuthica CCGG2742 for the control of this important phytopathogenic fungus.

Pathogen producing aflatoxin in contaminated sandwich: Identification and preservation.

The toxicity of the contaminated powder contributed to toxic aflatoxins has been well-known in the literature. However, before this study, the specific fungal strain behind aflatoxin production remained unidentified. Our research aimed to isolate and identify fungi from the tainted sandwiches while also assessing the preservation of sandwiches in ambient conditions. The study pinpointed Aspergillus flavus as the fungus responsible for aflatoxin production. Analysis revealed that the sandwich samples contaminated with pure A. flavus exhibited a significant Aflatoxin B1 (AFB1) concentration of 55.2 ± 0.21 ng/g, accompanied by a spore count of 2 × 106 Colony-Forming Unit (CFU)/g after ten days. In contrast, sandwich samples contaminated with the unspecified fungi displayed a lower AFB1 content of 16.21 ± 0.42 ng/g, with a spore count of 2.2 × 102 CFU/g after the same duration. In the prevention study, the efficacy of the ethanol spray method for inhibiting aflatoxin from A. flavus was investigated. Results demonstrated that a 70 % ethanol concentration at a ratio of 2.0 % total weight of the sandwich proved highly effective, significantly impeding fungal growth. This method extended the preservation time by sevenfold compared to the control. Importantly, tests at 2.0 % ethanol of the sandwich weight did not detect aflatoxin presence.

3D imaging and analysis to unveil the impact of microparticles on the pellet morphology of filamentous fungi.

Controlling the morphology of filamentous fungi is crucial to improve the performance of fungal bioprocesses. Microparticle-enhanced cultivation (MPEC) increases productivity, most likely by changing the fungal morphology. However, due to a lack of appropriate methods, the exact impact of the added microparticles on the structural development of fungal pellets is mostly unexplored. In this study synchrotron radiation-based microcomputed tomography and three-dimensional (3D) image analysis were applied to unveil the detailed 3D incorporation of glass microparticles in nondestructed pellets of Aspergillus niger from MPEC. The developed method enabled the 3D analysis based on 375 pellets from various MPEC experiments. The total and locally resolved volume fractions of glass microparticles and hyphae were quantified for the first time. At increasing microparticle concentrations in the culture medium, pellets with lower hyphal fraction were obtained. However, the total volume of incorporated glass microparticles within the pellets did not necessarily increase. Furthermore, larger microparticles were less effective than smaller ones in reducing pellet density. However, the total volume of incorporated glass was larger for large microparticles. In addition, analysis of MPEC pellets from different times of cultivation indicated that spore agglomeration is decisive for the development of MPEC pellets. The developed 3D morphometric analysis method and the presented results will promote the general understanding and further development of MPEC for industrial application.

Population distribution characteristics of mating type genes and genetic stability in Morchella sextelata.

The reproductive mode of morels (Morchella spp.) is governed by mating type genes, specifically MAT1-1 and MAT1-2. This study investigated the presence of mating type genes at various growth stages and in different parts of cultivated Morchella sextelata. This study revealed significant fluctuations in the detection ratio of the two mating type genes during ascocarps growth. Single ascospore strains with MAT1-1, MAT1-2 and both mating types were selected for experimentations. Stress stimuli including H2O2, Congo red and NaCl were introduced into the medium. Differences in the cultural and physiological characteristics of single spore strains were analyzed, and mating type genes were identified after subculturing to assess their stability. The results indicated that a total of 297 samples with a single mating type gene were detected in 480 samples selected from the five stages of fruiting body growth, accounting for 61.9%. Stress exposure influenced colony morphology, mycelial growth rate, and biomass, leading to significant increases in malondialdehyde content and osmotic adjustment compounds, including soluble protein and proline. Physiological and biochemical parameters varied among the three mating type strains under different stress conditions. Principal component analysis was used to calculate the weight values, which showed that the MAT1-2 strain exhibited the highest tolerance to chemical stresses, particularly oxidative stress. Subculturing under stress revealed that single mating type strains ceased growth by the 8th generation, whereas both mating type strains could continue to the 15th generation without loss of mating type genes, indicating broader environmental adaptability and higher viability. These findings offer novel insights into mating type gene function and serve as a scientific foundation for the development of high-yield, stress-resistant morel varieties.

Neg1 overexpression in Trichoderma harzianum T4 enhanced its ability to produce spores and antagonistic activity against phytopathogenic fungi.

Trichoderma harzianum T4 is a soil fungus that plays an important role in the biological control of plant diseases. The aim of this study was to functionally characterize the ß-1,6-glucanase gene Neg1 in T. harzianum T4 and to investigate the effect of its overexpression on biocontrol traits, especially antagonism against pathogenic fungi. We found that overexpression of Neg1 did not affect growth of T. harzianum but enhanced sporulation of T. harzianum T4 cultures. Generally, spores are closely related to the defense ability of defense fungi and can assist their proliferation and improve their colonization ability. Secondly, overexpression of Neg1 also increased the secretion level of various hydrolytic enzymes and enhanced the antagonistic ability against phytopathogenic fungi of Fusarium spp. The results suggest that Neg1 is a key gene for improving the biocontrol effect of T. harzianum T4, which contributes to a better understanding of the mechanism of action of T. harzianum T4 as a fungal biocontrol agent.

Sonic restoration: acoustic stimulation enhances plant growth-promoting fungi activity.

Ecosystem restoration interventions often utilize visible elements to restore an ecosystem (e.g. replanting native plant communities and reintroducing lost species). However, using acoustic stimulation to help restore ecosystems and promote plant growth has received little attention. Our study aimed to assess the effect of acoustic stimulation on the growth rate and sporulation of the plant growth-promoting fungus Trichoderma harzianum Rifai, 1969. We played a monotone acoustic stimulus (80 dB sound pressure level (SPL) at a peak frequency of 8 kHz and a bandwidth at -10 dB from the peak of 6819 Hz-parameters determined via review and pilot research) over 5 days to T. harzianum to assess whether acoustic stimulation affected the growth rate and sporulation of this fungus (control samples received only ambient sound stimulation less than 30 dB). We show that the acoustic stimulation treatments resulted in increased fungal biomass and enhanced T. harzianum conidia (spore) activity compared to controls. These results indicate that acoustic stimulation influences plant growth-promoting fungal growth and potentially facilitates their functioning (e.g. stimulating sporulation). The mechanism responsible for this phenomenon may be fungal mechanoreceptor stimulation and/or potentially a piezoelectric effect; however, further research is required to confirm this hypothesis. Our novel study highlights the potential of acoustic stimulation to alter important fungal attributes, which could, with further development, be harnessed to aid ecosystem restoration and sustainable agriculture.

Building blocks toward sustainable biofertilizers: variation in arbuscular mycorrhizal spore germination when immobilized with diazotrophic bacteria in biodegradable hydrogel beads.

AIM: We investigated whether there was interspecies and intraspecies variation in spore germination of 12 strains of arbuscular mycorrhizal fungi when co-entrapped with the diazotrophic plant growth-promoting bacteria, Azospirillum brasilense Sp7 in alginate hydrogel beads. METHODS AND RESULTS: Twelve Rhizophagus irregularis, Rhizophagus intraradices, and Funneliformis mosseae strains were separately combined with a live culture of Azospirillum brasilense Sp7. Each fungal-bacterial consortia was supplemented with sodium alginate to a 2% concentration (v/v) and cross-linked in calcium chloride (2% w/v) to form biodegradable hydrogel beads. One hundred beads from each combination (total of 1200) were fixed in solidified modified Strullu and Romand media. Beads were observed for successful spore germination and bacterial growth over 14 days. In all cases, successful growth of A. brasilense was observed. For arbuscular mycorrhizal fungi, interspecies variation in spore germination was observed, with R. intraradices having the highest germination rate (64.3%), followed by R. irregularis (45.5%) and F. mosseae (40.3%). However, a difference in intraspecies germination was only observed among strains of R. irregularis and F. mosseae. Despite having varying levels of germination, even the strains with the lowest potential were still able to establish with the plant host Brachypodium distachyon in a model system. CONCLUSIONS: Arbuscular mycorrhizal spore germination varied across strains when co-entrapped with a diazotrophic plant growth-promoting bacteria. This demonstrates that hydrogel beads containing a mixed consortium hold potential as a sustainable biofertilizer and that compatibility tests remain an important building block when aiming to create a hydrogel biofertilizer that encases a diversity of bacteria and fungi. Moving forward, further studies should be conducted to test the efficacy of these hydrogel biofertilizers on different crops across varying climatic conditions in order to optimize their potential.

The G-protein alpha subunit AaGA1 positively regulates vegetative growth, appressorium-like formation, and pathogenicity in Alternaria alternata.

AIMS: The Gα subunit is a major component of heterotrimeric G proteins, which play a crucial role in the development and pathogenicity of several model fungi. However, its detailed function in the causal agent of pear black spot (Alternaria alternata) is unclear. Our aim was to understand the characteristics and functions of AaGA1 in A. alternata. METHODS AND RESULTS: AaGA1 was cloned from A. alternata in this study, which encodes 353 amino acids and has a "G-alpha" domain. Mutant ΔAaGA1 resulted in reduced vegetative growth, conidiation, and spore germination. Especially, mutant ΔAaGA1 produced only fewer conidia on the V8A medium, and spore formation-related genes AbaA, BrlA, and WetA were significantly downregulated. More tolerance against cell wall-inhibiting agents was observed after the deletion of AaGA1. Moreover, AaGA1 deletion led to a significant reduction in melanin and toxin production. Interestingly, deletion of AaGA1 resulted in defective appressorium-like formations, complete loss of the ability to penetrate cellophane, and decreased infection on non-wound inoculated tobacco leaves. Cell wall-degrading enzyme-related genes PME, CL, Cut2, and LC were significantly downregulated in mutant ΔAaGA1 mutant, significantly reducing virulence on wound-inoculated pear fruits. CONCLUSIONS: The G protein alpha subunit AaGA1 is indispensable for fungal development, appressorium-like formations, and pathogenicity in A. alternata.

Inhibition of Fusarium graminearum growth and spore germination by a Streptomyces amritsarensis strain capable of killing and growing on Microcystis scum.

AIMS: Developing energy-saving and ecofriendly strategies for treating harvested Microcystis biomass. METHODS AND RESULTS: Streptomyces amritsarensis HG-16 was first reported to effectively kill various morphotypes of natural Microcystis colonies at very high cell densities. Concurrently, HG-16 grown on lysed Microcystis maintained its antagonistic activity against plant pathogenic fungus Fusarium graminearum. It could completely inhibit spore germination and destroy mycelial structure of F. graminearum. Transcriptomic analysis revealed that HG-16 attacked F. graminearum in a comprehensive way: interfering with replication, transcription, and translation processes, inhibiting primary metabolisms, hindering energy production and simultaneously destroying stress-resistant systems of F. graminearum. CONCLUSIONS: The findings of this study provide a sustainable and economical option for resource reclamation from Microcystis biomass: utilizing Microcystis slurry to propagate HG-16, which can subsequently be employed as a biocontrol agent for managing F. graminearum.