Growth Restriction of Rhizoctonia solani via Breakage of Intracellular Organelles Using Crude Extracts of Gallnut and Clove.

Plant diseases reduce crop yield and quality, hampering the development of agriculture. Fungicides, which restrict chemical synthesis in fungi, are the strongest controls for plant diseases. However, the harmful effects on the environment due to continued and uncontrolled utilization of fungicides have become a major challenge in recent years. Plant-sourced fungicides are a class of plant antibacterial substances or compounds that induce plant defenses. They can kill or inhibit the growth of target pathogens efficiently with no or low toxicity, they degrade readily, and do not prompt development of resistance, which has led to their widespread use. In this study, the growth inhibition effect of 24 plant-sourced ethanol extracts on rice sprigs was studied. Ethanol extract of gallnuts and cloves inhibited the growth of bacteria by up to 100%. Indoor toxicity measurement results showed that the gallnut and glove constituents inhibition reached 39.23 µg/mL and 18.82 µg/mL, respectively. Extract treated rice sprigs were dry and wrinkled. Gallnut caused intracellular swelling and breakage of mitochondria, disintegration of nuclei, aggregation of protoplasts, and complete degradation of organelles in hyphae and aggregation of cellular contents. Protection of Rhizoctonia solani viability reached 46.8% for gallnut and 37.88% for clove in water emulsions of 1000 µg/mL gallnut and clove in the presence of 0.1% Tween 80. The protection by gallnut was significantly stronger than that of clove. The data could inform the choice of plant-sourced fungicides for the comprehensive treatment of rice sprig disease. The studied extract effectively protected rice sprigs and could be a suitable alternative to commercially available chemical fungicides. Further optimized field trials are needed to effectively sterilize rice paddies.

Fungal mycelial mats used as textile by indigenous people of North America.

The indigenous people of the United States and Canada long have used forest fungi for food, tinder, medicine, paint, and many other cultural uses. New information about historical uses of fungi continues to be discovered from museums as accessions of fungi and objects made from fungi collected over the last 150+ years are examined and identified. Two textiles thought to be made from fungal mats are located in the Hood Museum of Art, Dartmouth College, and the Oakland Museum of California. Scanning electron microscopy and DNA sequencing were used to attempt to identify the fungus that produced the mats. Although DNA sequencing failed to yield a taxonomic identification, microscopy and characteristics of the mycelial mats suggest that the mats were produced by Laricifomes officinalis. This first report of fungal mats used for textile by indigenous people of North America will help to alert museum curators and conservators as well as mycological researchers to their existence and hopefully lead to more items being discovered that have been made from fungal fabric.

The inhibitory effect of volatile organic compounds produced by Bacillus subtilis CL2 on pathogenic fungi of wolfberry.

Bacillus subtilis strain CL2 is antagonistic to wolfberry postharvest pathogenic fungi. In this study, we isolated and screened this strain for in vitro experiments. The result of the two-sealed-base-plates method revealed that volatile organic compounds (VOCs) emitted from the strain CL2 inhibited the hyphal growth of four pathogenic fungi Mucor circinelloides LB1, Fusarium arcuatisporum LB5, Alternaria iridiaustralis LB7, and Colletotrichum fioriniae LB8. After exposure to VOCs for 5 days, the hyphal growth of the pathogen C. fioriniae LB8 was inhibited by 73%. Scanning electron microscopy revealed that the VOCs produced by B. subtilis CL2 caused the mycelium morphology of the pathogenic fungi to deform, twist, fold, and shrink. In the in vivo experiments, we noticed that VOCs could significantly reduce the weight loss rate of wolfberry fruits caused by the pathogenic fungus M. circinelloides LB1 and that the decay incidence rate were caused by the pathogenic fungi F. arcuatisporum LB5, A. iridiaustralis LB7, and C. fioriniae LB8. On the basis of the headspace-gas chromatography-ion mobility spectrometry analysis, seven VOCs produced by strain CL2 were identified. Among them, 2,3-butanedione and 3-methylbutyric acid are the main antifungal active substances. This study investigated the antifungal properties of VOCs produced by the strain CL2 on postharvest pathogenic fungi isolated from wolfberry fruits both in vivo and in vitro, thereby providing the theoretical basis for its future applications.

Antifungal Activity of Alpha-Mangostin against Colletotrichum gloeosporioides In Vitro and In Vivo.

We investigated alpha-mangostin (α-mangostin, α-MG), a xanthone natural product extracted from the pericarp of mangosteen (Garcinia mangostana), for its antifungal activities and possible mechanism against Colletotrichum gloeosporioides, which causes mango anthracnose. The results demonstrated that α-MG had a relatively high in vitro inhibitory activity against C. gloeosporioides among 20 plant pathogenic fungi. The median effective concentration (EC50) values of α-MG against mycelial growth were nearly 10 times higher than those of spore germination inhibition for both strains of C. gloeosporioides, the carbendazim-sensitive (CBD-s) and carbendazim-resistant (CBD-r). The results suggested that α-MG exhibited a better inhibitory effect on spore germination than on the mycelial growth of C. gloeosporioides. Further investigation indicated that the protective effect could be superior to the therapeutic effect for mango leaves for scab development. The morphological observations of mycelium showed that α-MG caused the accumulation of dense bodies. Ultrastructural observation further revealed that α-MG caused a decrease in the quantity and shape of the swelling of mitochondria in the mycelium cells of C. gloeosporioides. In addition, bioassays disclosed that the inhibitory activity of α-MG on spore germination was reduced by adding exogenous adenosine triphosphate (ATP). These results suggested that the mode of action of α-MG could be involved in the destruction of mitochondrial energy metabolism. The current study supports α-MG as a natural antifungal agent in crop protection.

Gene Organization, Expression, and Localization of Ribotoxin-Like Protein Ageritin in Fruiting Body and Mycelium of Agrocybe aegerita.

The edible mushroom Agrocybe aegerita produces a ribotoxin-like protein known as Ageritin. In this work, the gene encoding Ageritin was characterized by sequence analysis. It contains several typical features of fungal genes such as three short introns (60, 55 and 69 bp) located at the 5' region of the coding sequence and typical splice junctions. This sequence codes for a precursor of 156 amino acids (~17-kDa) containing an additional N-terminal peptide of 21 amino acid residues, absent in the purified toxin (135 amino acid residues; ~15-kDa). The presence of 17-kDa and 15-kDa forms was investigated by Western blot in specific parts of fruiting body and in mycelia of A. aegerita. Data show that the 15-kDa Ageritin is the only form retrieved in the fruiting body and the principal form in mycelium. The immunolocalization by confocal laser scanning microscopy and transmission electron microscopy proves that Ageritin has vacuolar localization in hyphae. Coupling these data with a bioinformatics approach, we suggest that the N-terminal peptide of Ageritin (not found in the purified toxin) is a new signal peptide in fungi involved in intracellular routing from endoplasmic reticulum to vacuole, necessary for self-defense of A. aegerita ribosomes from Ageritin toxicity.

Vermiculite as a culture substrate greatly improves the viability of frozen cultures of ectomycorrhizal basidiomycetes.

We assessed a new cryopreservation protocol that uses vermiculite as a culture substrate, called the vermiculite protocol (VP), by assessing the viability, recovery time of hyphae after revival, and colony diameter of cryosensitive ectomycorrhizal basidiomycete strains after storage for 2 weeks or 1 year in a vapour-phase liquid nitrogen tank. Twelve difficult-to-preserve strains of nine species (Amanita citrina, A. pantherina, A. rubescens, A. spissa, Kobayasia nipponica, Lactarius akahatsu, L. hatsudake, Sarcodon aspratus, and Tricholoma flavovirens) that did not achieve good revival after cryopreservation with our previous Homolka's perlite protocol and modified perlite protocol (MPP) experiments were used to assess the new methodology. Vermiculite and liquid medium were put into a cryotube and inoculated with an agar plug containing mycelia. The cryotube was cultured for various incubation times. After adequate mycelial growth, a mixture of cryoprotectants (5% dimethyl sulfoxide and 10% trehalose [5D10T] or 5% glycerol and 10% trehalose [5G10T]) was placed into the cryotube. The cryotube was frozen in a freezing container in a -80 °C freezer and then stored in vapour-phase liquid nitrogen. In the recovery test, 10 of 12 strains showed 100% revival after 2 weeks of storage in the 5G10T cryoprotectant, and all 12 strains showed 100% revival after 2 weeks of storage in the 5D10T cryoprotectant. Furthermore, all strains were viable after 1 year of storage in a vapour-phase liquid nitrogen tank. Thus, the VP is applicable to a wide range of ectomycorrhizal basidiomycete cultures, including highly cryosensitive strains.

Fungal mycelium classified in different material families based on glycerol treatment.

Fungal mycelium is an emerging bio-based material. Here, mycelium films are produced from liquid shaken cultures that have a Young's modulus of 0.47 GPa, an ultimate tensile strength of 5.0 MPa and a strain at failure of 1.5%. Treating the mycelial films with 0-32% glycerol impacts the material properties. The largest effect is observed after treatment with 32% glycerol decreasing the Young's modulus and the ultimate tensile strength to 0.003 GPa and 1.8 MPa, respectively, whereas strain at failure increases to 29.6%. Moreover, glycerol treatment makes the surface of mycelium films hydrophilic and the hyphal matrix absorbing less water. Results show that mycelium films treated with 8% and 16-32% glycerol classify as polymer- and elastomer-like materials, respectively, while non-treated films and films treated with 1-4% glycerol classify as natural material. Thus, mycelium materials can cover a diversity of material families.

Investigation of Mating Pheromone-Pheromone Receptor Specificity in Lentinula edodes.

The B mating-type locus of Lentinula edodes, a representative edible mushroom, is highly complex because of allelic variations in the mating pheromone receptors (RCBs) and the mating pheromones (PHBs) in both the Bα and Bß subloci. The complexity of the B mating-type locus, five Bα subloci with five alleles of RCB1 and nine PHBs and three Bß subloci with 3 alleles of RCB2 and five PHBs, has led us to investigate the specificity of the PHB-RCB interaction because the interaction plays a key role in non-self-recognition. In this study, the specificities of PHBs to RCB1-2 and RCB1-4 from the Bα sublocus and RCB2-1 from the Bb sublocus were investigated using recombinant yeast strains generated by replacing STE2, an endogenous yeast mating pheromone receptor, with the L. edodesRCBs. Fourteen synthetic PHBs with C-terminal carboxymethylation but without farnesylation were added to the recombinant yeast cells and the PHB-RCB interaction was monitored by the expression of the FUS1 gene-a downstream gene of the yeast mating signal pathway. RCB1-2 (Bα2) was activated by PHB1 (4.3-fold) and PHB2 (2.1-fold) from the Bα1 sublocus and RCB1-4 (Bα4) was activated by PHB5 (3.0-fold) and PHB6 (2.7-fold) from the Bα2 sublocus and PHB13 (3.0-fold) from the Bα5 sublocus. In particular, PHB3 from Bß2 and PHB9 from Bß3 showed strong activation of RCB2-1 of the Bß1 sublocus by 59-fold. The RCB-PHB interactions were confirmed in the monokaryotic S1-10 strain of L. edodes by showing increased expression of clp1, a downstream gene of the mating signal pathway and the occurrence of clamp connections after the treatment of PHBs. These results indicate that a single PHB can interact with a non-self RCB in a sublocus-specific manner for the activation of the mating pheromone signal pathways in L. edodes.

Combined Effect of Light and Nutrients on the Micromorphology of the White rot Fungus Cerrena Unicolor.

Light influences developmental pathways in fungi. Recent transcriptomic and biochemical analyses have demonstrated that light influences the metabolism of a white-rot basidiomycete Cerrena unicolor. However, the expression profile of genes involved in the growth and development, or micromorphological observations of the mycelium in response to variable lighting and culturing media, have not performed. We aim to reveal the effect of light and nutrients on C. unicolor growth and a potential relationship between the culture medium and lighting conditions on fungus micromorphological structures. Confocal laser scanning microscopy and scanning electron microscopy were employed for morphological observations of C. unicolor mycelium cultivated in red, blue, green, and white light and darkness on mineral and sawdust media. A comprehensive analysis of C. unicolor differentially expressed genes (DEGs) was employed to find global changes in the expression profiles of genes putatively involved in light-dependent morphogenesis. Both light and nutrients influenced C. unicolor growth and development. Considerable differences in the micromorphology of the mycelia were found, which were partially reflected in the functional groups of DEGs observed in the fungus transcriptomes. A complex cross-interaction of nutritional and environmental signals on C. unicolor growth and morphology was suggested. The results are a promising starting point for further investigations of fungus photobiology.

Characterization of brown film formed by Lentinula edodes.

Lentinula edodes is a widely-produced mushroom in China that forms a brown film via pigment accumulation on mature mycelial surfaces to ensure high-quantity and high-quality fruiting body formation. Here, ultraviolet-visible, infrared spectra, and elemental analyses predicted that the pigment in the brown film was melanin. Electron microscopy revealed the size, morphological characteristics, accumulation, and morphogenesis of electron-dense material, which were similar to those of melanin, as well as subcellular structural changes during brown film formation. The electron-dense material appeared as granules, vesicles, and polymers. The accumulation of electron-dense materials on the cell wall was followed plasmolysis, plasma membrane disruption, electron-dense material accumulation in the interstitial space, and gradual accumulation on the outer cell wall. Dolipore septa degradation and morphogenetic cell death occurred during browning. In the final stage of browning, the dolipore septum disappeared and the cell was nearly empty. This study provides a cytological foundation for evaluating the regulation of brown film formation in L. edodes.

Blistering1 Modulates Penicillium expansum Virulence Via Vesicle-mediated Protein Secretion.

The blue mold fungus, Penicillium expansum, is a postharvest apple pathogen that contributes to food waste by rotting fruit and by producing harmful mycotoxins (e.g. patulin). To identify genes controlling pathogen virulence, a random T-DNA insertional library was created from wild-type P. expansum strain R19. One transformant, T625, had reduced virulence in apples, blistered mycelial hyphae, and a T-DNA insertion that abolished transcription of the single copy locus in which it was inserted. The gene, Blistering1, encodes a protein with a DnaJ domain, but otherwise has little homology outside the Aspergillaceae, a family of fungi known for producing antibiotics, mycotoxins, and cheese. Because protein secretion is critical for these processes and for host infection, mass spectrometry was used to monitor proteins secreted into liquid media during fungal growth. T625 failed to secrete a set of enzymes that degrade plant cell walls, along with ones that synthesize the three final biosynthetic steps of patulin. Consequently, the culture broth of T625 had significantly reduced capacity to degrade apple tissue and contained 30 times less patulin. Quantitative mass spectrometry of 3,282 mycelial proteins revealed that T625 had altered cellular networks controlling protein processing in the endoplasmic reticulum, protein export, vesicle-mediated transport, and endocytosis. T625 also had reduced proteins controlling mRNA surveillance and RNA processing. Transmission electron microscopy of hyphal cross sections confirmed that T625 formed abnormally enlarged endosomes or vacuoles. These data reveal that Blistering1 affects internal and external protein processing involving vesicle-mediated transport in a family of fungi with medical, commercial, and agricultural importance.

Disclosure of the Molecular Mechanism of Wheat Leaf Spot Disease Caused by Bipolaris sorokiniana through Comparative Transcriptome and Metabolomics Analysis.

Wheat yield is greatly reduced because of the occurrence of leaf spot diseases. Bipolaris sorokiniana is the main pathogenic fungus in leaf spot disease. In this study, B. sorokiniana from wheat leaf (W-B. sorokiniana) showed much stronger pathogenicity toward wheat than endophytic B. sorokiniana from Pogostemon cablin (P-B. sorokiniana). The transcriptomes and metabolomics of the two B. sorokiniana strains and transcriptomes of B. sorokiniana-infected wheat leaves were comparatively analyzed. In addition, the expression levels of unigenes related to pathogenicity, toxicity, and cell wall degradation were predicted and validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis. Results indicated that pathogenicity-related genes, especially the gene encoding loss-of-pathogenicity B (LopB) protein, cell wall-degrading enzymes (particularly glycosyl hydrolase-related genes), and killer and Ptr necrosis toxin-producing related unigenes in the W-B. sorokiniana played important roles in the pathogenicity of W-B. sorokiniana toward wheat. The down-regulation of cell wall protein, photosystem peptide, and rubisco protein suggested impairment of the phytosynthetic system and cell wall of B. sorokiniana-infected wheat. The up-regulation of hydrolase inhibitor, NAC (including NAM, ATAF1 and CUC2) transcriptional factor, and peroxidase in infected wheat tissues suggests their important roles in the defensive response of wheat to W-B. sorokiniana. This is the first report providing a comparison of the transcriptome and metabolome between the pathogenic and endophytic B. sorokiniana strains, thus providing a molecular clue for the pathogenic mechanism of W-B. sorokiniana toward wheat and wheat's defensive response mechanism to W-B. sorokiniana. Our study could offer molecular clues for controlling the hazard of leaf spot and root rot diseases in wheat, thus improving wheat yield in the future.

Interactions of free-living amoebae with the rice fungal pathogen, Rhizoctonia solani.

OBJECTIVE: Rhizoctonia solani is a soil-borne fungal pathogen of many important crop plants. In rice, R. solani causes sheath blight disease, which results in devastating grain yield and quality losses. Few methods are available to control this pathogen and classic single gene resistance mechanisms in rice plants have not been identified. We hypothesize that alternate means of control are available in the environment including free-living amoebae. Amoebae are soil-, water- and air-borne microorganisms that are predominantly heterotrophic. Many amoeba species are mycophagous, and several harm their prey using mechanisms other than phagocytosis. Here, we used light and scanning electron microscopy to survey the interactions of R. solani with four amoeba species, with the goal of identifying amoebae species with potential for biocontrol. RESULTS: We observed a wide range of responses during interactions of R. solani with four different free-living amoebae. Two Acanthamoeba species encyst in co-cultures with R. solani at higher rates than medium without R. solani. Vermamoeba vermiformis (formerly Hartmanella vermiformis) attach to R. solani mycelium and are associated with mycelial shriveling and perforations of fungal cell walls, indicating an antagonistic interaction. No phenotypic changes were observed in co-cultures of Dictyostelium discoideum and R. solani.

Processing Embryo, Eggshell, and Fungal Culture for Scanning Electron Microscopy.

Although scanning electron microscopy (SEM) is being widely used for the ultra-structural analysis of various biological and non-biological samples, methods involved in processing different biological samples involve unique practices. All conventional practices described in the literature for processing samples still find useful applications, but subtle changes in the sample preparation can alter image quality, as well as, introduce artifacts. Hence, using a unique sample preparation technique specific to the type of tissue analyzed is required to obtain a good quality image with ultrastructural resolution. The focus of this study is to provide the optimal sample preparation protocols for imaging embryos, rigid eggshells, and fungal cultures using SEM. The following optimizations were recommended to yield good results for the three different delicate biological samples studied. Use of milder fixatives like 4% paraformaldehyde or 3% glutaraldehyde followed by dehydration with ethanol series is mandatory. Fungal mycelium on agar blocks obtained by slide cultures yields a better ultrastructural integrity compared to cultures taken directly from agar plates. Chemical drying of embryos with HMDS provides drying without introducing surface tension artifacts compared to critical point drying. HMDS prevents cracking caused by shrinkage as samples are less brittle during drying. However, for fungal culture, critical point drying provides acceptable image quality compared to chemical drying. Eggshells can be imaged with no special preparation steps except for thorough washing and air drying prior to mounting. Preparation methodologies were standardized based on acceptable image quality obtained with each trial.

Sodium pheophorbide a has photoactivated fungicidal activity against Pestalotiopsis neglecta.

Sodium pheophorbide a (SPA) is a natural photosensitizer. To explore its antifungal activity and mechanism, we studied its inhibitory effects on spore germination and mycelial growth of Pestalotiopsis neglecta. We used sorbitol, 2-thiobarbituric acid (TBA) and electron microscopy to determine its effects on cell wall integrity, cell membrane lipid peroxidation and mycelial morphology. Finally, the effects of SPA on enzyme activity in mycelia were determined. The results showed that SPA effectively inhibited spore germination and mycelial growth of P. neglecta under light conditions (4000 lx, 24 h). Scanning electron microscopy (SEM) revealed that SPA treatment resulted in a roughened, twisted and knotted mycelial surface and abnormal mycelial growth. SPA influenced cell wall integrity, and the content of MDA, a cell membrane lipid peroxidation product was significantly increased (P < 0.05). SPA also significantly inhibited SOD, POD and PG activity, but enhanced PPO activity (P < 0.05). In conclusion, SPA may have potential to become a biological pesticide.

Effects of glutamic acid on the production of monacolin K in four high-yield monacolin K strains in Monascus.

Monascus purpureus is a traditional Chinese microbe that can be used as a medicinal herb and is edible. To improve the yield of monacolin K, we optimized the medium of M. purpureus with high-yield monacolin K strains. When high-yield strains C8, D8, E3, and I1 were grown in glutamic medium instead of the original medium, monacolin K production was increased. Among these strains, C8 exhibited the highest monacolin K production in glutamic acid medium, with levels increased 4.80-fold. RT-qPCR demonstrated that glutamic acid enhanced the expression of mokC and mokG. Observation of Monascus mycelium morphology using SEM showed that mycelia exhibited more folds, swelling, curves, and fractures. Thus, glutamic acid may promote the growth of the mycelium and appeared to increase the permeability of the cell membrane. This lays a foundation for research on the regulatory effect of glutamic acid and provides a theoretical basis for the industrialization and commercialization of Monascus.

The possible mechanism of the formation of silver nanoparticles by Penicillium cyclopium.

This contribution describes the biomineralization of silver nanoparticles by the microbial reduction of Ag (I) ions using the mycelium and the cell-free extract of Penicillium cyclopium. Different techniques, such as UV-Vis, SEM, TEM, FT-IR and GPC were used to characterize the obtained nanoparticles and understand the mechanism of their biosynthesis. The SEM and TEM images demonstrated the presence of silver nanoparticles on the mycelia surface suggesting that these particles are synthesized on the fungal cell wall. FT-IR analysis of the mycelium revealed two main types of compounds (saccharides and proteins) and these molecules might be involved in the formation of silver nanoparticles on the surface of mycelium. Ultraviolet-visible spectroscopy and TEM analysis confirmed the formation of silver nanoparticles with different shapes by the cell-free extract of P. cyclopium. Their size ranges from 12 to 25 nm and possess an average size of 16 ±â€¯6 nm. GPC analysis of this filtrate revealed a few peaks responsible for polysaccharides and proteins presence. The only protein fraction with the mass approximately to 5000 Da indicated the formation of silver nanoparticles. Polypeptide(s) as the major molecules involved in biomineralization of silver by the cell-free extract of P. cyclopium are suggested. Enzymatic synthesis of silver nanoparticles by the mycelium and the cell-free extract of P. cyclopium is excluded.

p-Anisaldehyde Exerts Its Antifungal Activity Against Penicillium digitatum and Penicillium italicum by Disrupting the Cell Wall Integrity and Membrane Permeability.

Penicillium digitatum and P. italicum are the two important postharvest pathogens in citrus, causing about 90% of the total loss of citrus fruit during storage and transportation. Natural fungicides such as essential oils have been widely used instead of chemical fungicides for preventing and controlling postharvest diseases. In this research, p-anisaldehyde exhibited a strong inhibitory effect on P. digitatum and P. italicum, with the minimum inhibitory concentration and minimum fungicidal concentration values of both being 2.00 µl/ml. Additionally, p-anisaldehyde visibly inhibited both the green mold and blue mold development of citrus fruits inoculated with P. digitatum and P. italicum. The mycelia morphologies of these pathogens were greatly altered, and the membrane permeability and cell wall integrity of mycelia were severely disrupted under p-anisaldehyde treatment. These results suggest that the antifungal activity of p-anisaldehyde against P. digitatum and P. italicum can be attributed to the disruption of the cell wall integrity.

Effects of the dinitroaniline fungicide fluazinam on Fusarium fujikuroi and rice.

Fusarium fujikuroi is the primary causal agent of rice bakanae disease. Fluazinam is a protective dinitroaniline fungicide which could interrupt the fungal cell's energy production. Little is known about the effects of fluazinam on F. fujikuroi. In this study, baseline sensitivity of F. fujikuroi to fluazinam was determined using 103 isolates collected from diseased young rice of different fields in Shaoxing of Zhejiang Province and Huaian of Jiangsu Province of China in 2016. The EC50 values of fluazinam on inhibiting mycelial growth against 103 isolates of F. fujikuroi ranged from 0.0621 to 0.5446 µg/mL with the average value of 0.2038 ±â€¯0.0099 µg/mL (mean ±â€¯standard error). The EC50 values of fluazinam on suppressing conidium germination against 103 isolates of F. fujikuroi ranged from 0.1006 to 0.9763 µg/mL with the mean value of 0.3552 ±â€¯0.0181 µg/mL. Treated with fluazinam, hyphae of F. fujikuroi were contorted, offshoot of top mycelia increased, conidial production descreased significantly and exopolysaccharide (EPS) content did not change significantly while peroxidase (POD) activity significantly decreased. Meanwhile, cell membrane permeability increased after treated with fluazinam. The analysis of cell ultrastructure indicated that fluazinam could damage the membrane structure of F. fujikuroi and cause a large number of vacuoles formed. In addition, fluazinam did not affect germination rate, plant height and fresh weight of rice, which indicated that fluazinam was safe to rice. All the results indicated that fluazinam had strong antifungal activity against F. fujikuroi and a potential application in controlling rice bakanae disease. These results will provide useful information for management of rice bakanae disease caused by F. fujikuroi and further increase our understanding about the mode of action of fluazinam against F. fujikuroi and other phytopathogens.

Peltaster gemmifer: A new species in the sooty blotch and flyspeck species complex from the United States.

Sooty blotch and flyspeck (SBFS) fungi infect the cuticle of fruit, including apple fruit, and produce pigmented colonies. A new member of this fungal complex in the genus Peltaster is described on the basis of molecular and morphological evidence. The SBFS complex is a diverse group of ectophytic fungi that reside primarily within the order Capnodiales. Sooty blotch and flyspeck isolates from apple orchards in the central United States were subjected to parsimony and Bayesian analyses based on the internal transcribed spacer regions of nuc rDNA, the partial translation elongation factor 1-α gene, and the partial mitochondrial small subunit rRNA gene. Phylogenetic analysis delineated a new species, Peltaster gemmifer, from P. cerophilus and P. fructicola. Peltaster gemmifer conidiophores bear primary conidia that produce secondary conidia either through budding or through microcyclic conidiation; these were not seen in cultures of P. cerophilus and P. fructicola. On cellulose membrane that was placed on water agar amended with apple juice, P. gemmifer produced brown to black pycnothyria in a superficial brownish mycelial mat, similar to the colonies produced on apple fruit. Findings from the present study add to the >80 named and putative SBFS species so far described worldwide.