Fungus Alternaria Research Articles

Exploring Endophytic Fungi from Humulus lupulus L. for Biocontrol of Phytopathogenic Fungi

Humulus lupulus L. (hop) is a crucial crop within the brewing industry and a rich source of bioactive compounds. Traditionally concentrated in northeast regions of Europe, hop cultivation has expanded towards southern territories such as Italy over recent decades. Managing phytosanitary threats in Mediterranean climates poses challenges due to limited knowledge and registered agrochemicals. In pursuit of eco-friendly alternatives for disease management, we isolated 262 endophytic fungal strains from wild hop roots, stems, leaves, and flowers. Through phylogenetic analyses, we identified 51 operational taxonomic units. Dominant species such as Ilyonectria macrodidyma, Penicillium sp., Diaporthe columnaris, Plectosphaerella cucumerina, and Fusarium oxysporum were exclusive to roots. In contrast, Alternaria spp. and Epicoccum spp. were prevalent in other tissues, and Botrytis cinerea was exclusively detected in female flowers. We tested seven isolates—Epicoccum sp., Aureobasidium pullulans, Plectosphaerella cucumerina, Stemphylium vesicarium, Periconia byssoides, Talaromyces wortmannii, and Nigrospora sphaerica—against the four phytopathogenic fungi Alternaria sp., Fusarium oxysporum, Botrytis cinerea, and Sclerotinia sclerotiorum. All endophytes exhibited antagonistic effects against at least one pathogen, with Plectosphaerella cucumerina showing the strongest inhibition against Alternaria sp. This study marks the first exploration of endophytic fungi from various hop tissues. All isolated strains were ex situ conserved for future bioactivity assessments and biotechnological applications. Original data with a key relevance for the environmentally friendly management of plant diseases are provided.

Chitosan reduces naturally occurring plant pathogenic fungi and increases nematophagous fungus Purpureocillium in soil under field conditions

Chitosan effects on soil properties were analysed both under laboratory conditions by incubation with constant humidity and temperature and under field conditions in two persimmon field plots with conventional and ecological management. Chitosan was applied in solution or as coacervates. Application of chitosan reduced soil pH, conductivity (CE), and cation exchange capacity (CEC) in pots when applied at field capacity. Chitosan did not affect field soil respiration, which is greatly dependent of soil moisture and temperature. Metabarcoding showed that chitosan significantly modifies the fungal genera composition of ecologically managed field soil. On the contrary, chitosan caused no significant differences in bacterial taxa composition of soil under field conditions. Chitosan coacervates increased naturally occurring nematophagous fungus Purpureocillium (ca. 50-fold) in soil with respect to chitosan solution-treated soil and untreated controls. In addition, chitosan reduced the inoculum of plant pathogenic fungi Alternaria and Fusarium (20% and 50%, respectively) in field soil. Soil microbial network analysis for ITS2+V1–V2 regions revealed that the nematophagous fungus Pochonia promoted network clustering into modules. Furthermore, network analysis for ITS2+V3–V4 regions showed that the nematode trapping-fungus Orbilia and bacteria belonging to Acidimicrobiales and Cytophagales significantly contributed to network clustering in field soil. Our results show that chitosan coacervates increased soil nematophagous microbiota and that both nematode egg parasites and trapping fungi help to structure soil microbiota.

ApWD40a, a Member of the WD40-Repeat Protein Family, Is Crucial for Fungal Development, Toxin Synthesis, and Pathogenicity in the Ginseng Alternaria Leaf Blight Fungus Alternaria panax.

Alternaria panax, the primary pathogen that causes ginseng Alternaria leaf blight disease, can lead to a 20-30% reduction in ginseng yield. WD40 repeat-containing proteins are evolutionarily conserved proteins with diverse functions between different organisms. In this study, we characterized the roles of a WD40 repeat-containing protein in A. panax. The deletion of ApWD40a impaired the mycelial growth, reduced the sporulation, and significantly decreased the efficiency in utilizing various carbon sources. The ΔApwd40a mutant showed increased sensitivity to osmotic stress and metal ion stress induced by sorbitol, NaCl, and KCl, but decreased the sensitivity to a cell wall stress factor (SDS) and oxidative stress factors (paraquat and H2O2). Pathogenicity assays performed on detached ginseng leaves and roots revealed that the disruption of ApWD40a significantly decreased the fungal virulence through attenuating melanin and mycotoxin production by A. panax. A comparative transcriptome analysis revealed that ApWD40a was involved in many metabolic and biosynthetic processes, including amino acid metabolism, carbon metabolism, sulfate metabolic pathways, and secondary metabolite pathways. In particular, a significantly upregulated gene that encoded a sulfate permease 2 protein in ΔApwd40a, named ApSulP2, was deleted in the wild-type strain of A. panax. The deletion of ApSulP2 resulted in reduced biomass under sulfate-free conditions, demonstrating that the sulfate transport was impaired. Taken together, our findings highlight that ApWD40a played crucial roles in different biological processes and the pathogenicity of A. panax through modulating the expressions of genes involved in various primary and secondary metabolic processes.

Assessment of Alternaria Toxins and Pesticides in Organic and Conventional Tomato Products: Insights into Contamination Patterns and Food Safety Implications.

Alternaria toxins (ATs) are a group of toxins produced by Alternaria fungi that frequently contaminate tomatoes and tomato products. Recently, the European Food Safety Authority evaluated ATs for their genotoxic and carcinogenic properties. Alternaria infestation is often controlled using ad hoc treatment strategies (fungicides). In this study, two analytical methods were developed, validated and applied for the determination of five ATs and 195 pesticides in tomato products collected from the Italian market. Two distinct groups, organic (n = 20) and conventional (n = 20) Italian tomato sauces, were characterized in depth. Tenuazonic acid, alternariol and alternariol monomethyl ether were found up to 517, 27 and 7.1 µg/kg, respectively, while pesticides were detected between 0.0026 and 0.0421 mg/kg in conventional products, and, interestingly, up to 0.0130 mg/kg in organic products. No correlation emerged between the detected levels of ATs and pesticides and the type of tomato cultivation, but the probability of pesticide contamination in conventional products was eight times higher than in organics. Some considerations about exposure assessment and risk characterization for ATs were also proposed in the overall population and in more sensitive and/or exposed subgroups, underlining the need for new focused toxicological and monitoring studies to establish reliable reference values. Moreover, these data highlight that fungicide treatments may not protect tomatoes from ATs contamination, although it may remove fungi infestation. As organic product consumption is increasing, it is important to lay down dedicated regulations for maximum permitted levels to ensure the food safety of these products that are often perceived by consumers as a healthier and environmentally friendlier choice.

Potency of the Endophytic Fungi Cheatomum globosum and Trichoderma harzianum in Resisting the Pathogenic Fungus Alternaria solani That Causes Leaf Spot in Tomato Plants

Potency of the Endophytic Fungi Cheatomum globosum and Trichoderma harzianum in Resisting the Pathogenic Fungus Alternaria solani That Causes Leaf Spot in Tomato Plants

Evaluation of Some Plant Extract and Bio- Fungi to Control Leaf Spot of Safflower Plant Disease

This research study aims at evaluating the effectiveness of the biological fungus Trichoderma longibrachiatum , Trichoderma harzianum and some plant extracts kinocarpus( Leucaena leucocephala) ,Eucalyptus (Eucalyptus camaldulensis), henna leaf extract ( Lawsonia inermis ). Besides, finding the best concentrations of plant extracts to stimulate the systemic resistance to safflower plant Carthamus tinctorius, against alternaria leaf spot. The results made clear that the fungus Alternaria alternata had clear effect in reducing the percentage of germination of safflower seeds as the rate reached 53.33% while the percentage of seedling damping off reached 81.11% compared with control treatment 93.33, 0 % respectively. The biological fungi have high effectiveness with inhibiting growth of fungus Alternaria alternata, according to results as the antagonisim level was (1) as in bell scale. Plant extract also gave a high efficiency in preventing the infectious fungus's growth as rate of kinokarpus , henna, eucalyptus reached 75.78 ,74.59 , 70.64 % respectively. Effect of the extracts in inhibiting the pathogenic fungus went up with increased concentration, as the highest percentage of inhibition was reached at a concentration of 10 % for tested extracts, the kinocarpus plant gave the highest rate reached 91.51%, while the percentage reached 89.62, 80.36 % for henna and eucalyptus extract, respectively.

Efficacy of Biorational Insecticides and Entomopathogenic Fungi for Controlling Cassida vittata Vill. (Coleoptera: Chrysomelidae) in Sugar Beet Crops.

The sugar beet flea beetle, Cassida vittata Vill. (Coleoptera: Chrysomelidae), is a major pest in Morocco's sugar beet crops and is primarily controlled with chemical insecticides despite environmental concerns. Our aim was to assess the impact of three biorational insecticides (spinosad at 30-7.5cc/hL, mineral oil at 2000-250cc/hL, and potassium salts of fatty acids at 1500-375cc/hL) and two entomopathogenic fungi (Alternaria murispora and Alternaria destruens applied at 1.0 × 108, 5.0 × 107, and 2.5 × 107 conidia mL-1) both individually and in combination on C. vittata adults. All treatments were conducted at 25 ± 1°C, with mortality recorded over 10days. Conidial germination was highest for A. murispora with mineral oil (98.4%). Alternaria destruens showed consistently high germination across treatments. At 100% concentration, A. murispora + mineral oil and A. destruens + mineral oil treatments achieved 96.67 and 92.00% mortality, respectively. Median survival times (MST) for A. murispora were 6.0days at 100% concentration, increasing to 10.0days at lower concentrations, while A. destruens had a consistent 10.0days MST. LC50 for A. murispora was 1.3 × 107 conidia mL-1 alone, increasing to 2.2 × 107 with spinosad, but remained 1.7 × 107 with potassium salts of fatty acids. For A. destruens, LC50 was 4.2 × 107 conidia mL-1 alone, decreasing to 1.5 × 107 with mineral oil, and 3.1 × 107 with potassium salts of fatty acids. Combining A. murispora with mineral oil and potassium salts of fatty acids enhanced efficacy against C. vittata.

Antiphytopathogenic Diphenyl Ethers from the Marine-derived Fungus Aspergillus sydowii

Background: Natural products from the marine-derived Aspergillus sp. have great potential in agricultural usage due to their broad biological activities. Objective: This study was designed to investigate the antiphytopathogenic compounds from marinederived fungus Aspergillus sydowii LW09. Methods: The compounds were isolated and purified by chromatography methods, and their structures were elucidated by analysis of the NMR and MS spectroscopic data as well as comparison with those of literature. All compounds were evaluated for antibacterial activities against phytopathogenic bacteria Pseudomonas syringae and Ralstonia solanacarum, along with spore germination inhibition of phytopathogenic fungi Fusarium oxysporum and Alternaria alternata. Results: Two diphenyl ethers violaceols I (1) and II (2), along with two alkaloids acremolin (3) and WIN 64821 (4) were isolated from the fermentation extracts of A. sydowii LW09. Compound 1 showed significant antibacterial activity against P. syringae and R. solanacarum with the same MIC values of 4 μg/mL, while compound 2 showed obvious antibacterial activity against P. syringae and R. solanacarum with MIC values of 2 and 1 μg/mL, respectively. Moreover, both 1 and 2 could inhibit the spore germination of F. oxysporum in the concentration range of 64–128 μg/mL. In addition, violaceol I (1) also inhibited the spore germination of A. alternata at 128 μg/mL. Conclusion: This study provided the potential antiphytopathogenic drug candidate for further studies.

Effect of Endophytic Bacteria Bacillus subtilis 26D and Bacillus velezensis M66 on Resistance of Potato Plants to the Causative Agent of Early Blight Alternaria solani

The effect of Bacillus velezensis M66 and Bacillus subtilis 26D bacteria on the resistance of potato plants to the necrotrophic fungus Alternaria solani (the causative agent of early blight) was studied. The accumulation of viable bacterial cells of these strains in the internal tissues of the potato stem, roots, and tubers over a long period of time was demonstrated for the first time. A significant reduction in the area affected by the early blight on leaves inoculated with plant endophytes, as well as inhibition of the pathogen growth under the action of bacterial strains, was detected, which can be explained by the synthesis of lipopeptide antibiotics (the genes responsible for the synthesis of which were found by the PCR method) and proteolytic enzymes (the activity of which was demonstrated in vitro). The formation of plant resistance under the influence of inoculation with B. subtilis 26D and B. velezensis M66 was accompanied by an accumulation of hydrogen peroxide in the first hours after plant infection with A. solani spores and by a decrease in this index at the late stages of pathogenesis due to an increase in the activity of catalase and peroxidases. Limitation of the fungus spread was accompanied by an increase in the activity of proteinase inhibitors in plants, which probably decreased the negative effect of proteolytic enzymes of the necrotrophic pathogen A. solani. It can be assumed that the inoculation of plants with bacterial cells of the B. velezensis M66 strain contributed to the formation of resistance of potato plants to the early blight by efficient priming of the phytoimmune potential, which is comparable to the B. subtilis 26D strain (successfully used in the field conditions), an active component of the Fitosporin-M biopreparation.

Genomic Insights into the Bactericidal and Fungicidal Potential of Bacillus mycoides b12.3 Isolated in the Soil of Olkhon Island in Lake Baikal, Russia.

The dispersal of plant pathogens is a threat to the global economy and food industry which necessitates the need to discover efficient biocontrol agents such as bacteria, fungi, etc., inhibiting them. Here, we describe the Bacillus mycoides strain b12.3 isolated from the soil of Olkhon Island in Lake Baikal, Russia. By applying the co-cultivation technique, we found that the strain inhibits the growth of plant pathogens, such as the bacteria Xanthomonas campestris, Clavibacter michiganensis, and Pectobacterium atrospecticum, as well as the fungus Alternaria solani. To elucidate the genomic fundament explaining these activities, we leveraged next-generation whole-genome sequencing and obtained a high-quality assembly based on short reads. The isolate bore seven known BGCs (biosynthetic gene clusters), including those responsible for producing bacillibactin, fengycin, and petrobactin. Moreover, the genome contained insecticidal genes encoding for App4Aa1, Tpp78Ba1, and Spp1Aa1 toxins, thus implicating possible pesticidal potential. We compared the genome with the 50 closest assemblies and found that b12.3 is enriched with BGCs. The genomic analysis also revealed that genomic architecture corresponds to the experimentally observed activity spectrum implying that the combination of produced secondary metabolites delineates the range of inhibited phytopathogens Therefore, this study deepens our knowledge of the biology and ecology of B. mycoides residing in the Lake Baikal region.

Analysis of fungal and mycotoxin contamination of winter wheat grain grown in Krasnodarskiy Krai in 2023

Using quantitative PCR (qPCR) and high-performance liquid chromatography with tandem mass spectrometry (HPLC MS/MS) ubiquitous presence of Fusarium and Alternaria fungi and their mycotoxins was detected in winter wheat grain grown in Krasnodarskiy Krai in 2023. All samples contained DNA of Fusarium producing trichothecene mycotoxins (Tri-Fusarium) in the range of 244–23537 pg/µg. DNA of Fusarium producing fumonisins was detected in 35 % of grain samples at 27–923 pg/µg. All samples contained Alternaria sect. Alternaria and sect. Infectoriae DNA at average levels of 3630±144 and 6814±214 pg/µg, respectively. Of the 36 analyzed mycotoxins, 17 metabolites were found in the grain samples: from 3 to 11 mycotoxins in each sample. Among Fusarium mycotoxins, most common were deoxynivalenol (DON) (in 79 % of samples), deoxynivalenol-3-glucoside (50 %), HT-2 toxin (47 %), and beauvericin (70 %). In two samples (6 % of the total), the maximum permissible DON concentration was exceeded by 2–3 times. A significant positive correlation between Tri-Fusarium DNA and DON content, as well as zearalenone, was found, indicating F. graminearum prevalence among the pathogens causing Fusarium head blight in this region. A high occurrence of mycotoxins produced by Alternaria fungi alternariol (82 % of contaminated samples), tentoxin (TEN) (100 %), and tenuazonic acid (79 %) in the grain was revealed. A significant correlation between the content of Alternaria sect. Alternaria DNA and two mycotoxins alternariol monomethyl ether and TEN was found. Significant distinctions were found between different Krasnodarskiy Krai locations in grain contamination levels with Fusarium, Alternaria fungi and mycotoxins.

Machine Learning-Potato Leaf Disease Detection App (MR-PoLoD)

Potato production in Indonesia has grown very rapidly, making Indonesia the largest potato producer in Southeast Asia. However, there are challenges for farmers in growing potatoes. Such as treating potatoes for various diseases. 2 diseases will occur in potato plants if not treated quickly, namely early blight disease caused by the fungus Alternaria solani and late blight disease caused by the microorganism Phytophthora infestans. The project "Potato Plant Leaf Disease Detector (MR-PoLod)" aims to design an android application that can classify leaves on potato plants into 3 classifications, namely healthy, early, and late blight disease. This application uses the CNN (Convolutional Neural Network) Machine Learning Algorithm because currently, CNN is recognized as the most efficient and effective model in pattern and image recognition tasks. This application uses the Python programming language which is rich in library and framework availability so that it can meet the needs of machine learning and image classification tasks. The total data used for training data, data validation and data testing is 3165 images. With each division of the data process on the training data of 70%, validation of 15% testing of 15% to test the effectiveness of the model that has been created. The performance of MR-PoLod for each class, obtained a precision value, recall, and f1-score of 0.99. Likewise, the accuracy value achieved by the model is 0.99 or 99%. Thus, the expected application can facilitate farmers in classifying diseases on potato plant leaves.

INFLUENCE OF ALTERNARIA SPP. FUNGI METABOLITES ON DEVELOPMENT OF WHEAT SPROUTS

The study purpose was in vitro investigation of phytotoxic activity of culture broth filtrates (CBFs) of five Alternaria Spp. fungi isolates on development of wheat sprouts. Fungi isolates were received from wheat seeds cultivated under conditions of Northern Kazakhstan. According to the study findings, culture filtrates of all the isolates studied varied with regard to their influence on wheat sprout development. Stimulant effects on seed germinating power were revealed with 14- and 21-day CBFs of A. infectoria (7/4), 14-day CBF of A. brassicae (7/2) and 21-day CBF of A. porri (8/1). It was found that long-term cultivation of fungi on a culture medium contributed to media pH modification towards alkalization due to production of metabolites of various chemical nature, including toxins, which could trigger growth inhibition of radicles and sprouts. However, the CBFs were predominantly low-toxic or non-toxic. Under effect of the 14-day CBF, significant positive correlation was identified between pH values and sprout lengths (0,86±0,25), while negative correlation was found between pH values and germinating power (-0,75±0,33). Change of pH value on the 21st day significantly affected radicle length (-0,92±0,20). Based on the findings it can be concluded that the 14-day CBF of all the Alternaria fungi isolates studied was most toxic for wheat sprouts.

Alternariosis or brown spot of pomegranate bushes in the western part of Azerbaijan

Abstract Alternariosis or brown spot (Alternaria alternata (Fr.) Keissl.) is a widespread disease of pomegranate bushes in Azerbaijan. The disease occurs mainly in the western part of the country. Alternariosis or brown spot on pomegranate bushes (Alternaria alternata (Fr.) Keissl.) is found mainly on leaves and fruits. On ripening pomegranate fruits, the lesion begins with small brown or black spots that increase in size and become round or oval. The causative agents of alternariosis or brown spot on pomegranate bushes (Alternaria alternata (Fr.) Keissl.) are imperfect fungi of the genus Alternaria, from the order Hyphomycetales; Alternaria alternata (Fr.) Keissl is more common in the conditions of the western part of Azerbaijan. Alternariosis or brown spot (Alternaria alternata (Fr.) Keissl.) causes the greatest harm in conditions of sufficient moisture. The aim of the article is to present the results of studies on the distribution, intensity of development and harmfulness of alternariosis or brown spot of pomegranate bushes (Alternaria alternata (Fr.) Keissl.), as well as biological effectiveness of fungicides used to control alternariosis, in the western part of Azerbaijan. Research methods used are generally accepted in phytopathology and plant protection to identify and record the infectious potential of the causative agent of alternariosis or brown spot of pomegranate bushes (Alternaria alternata (Fr.) Keissl.) as well as to disease monitoring. During field studies, the fungicides used were 0.4% Selphate (37.5% copper oxychloride + 16% zineb), 0.05% Azoxifene (20% azoxystrobin + 12.5% difenoconazole), 0.05% Conazole (25% difenoconazole) and 0.3% P-oxiride (50% copper oxychloride) and determined their biological effectiveness accordingly. In the last 5 years, there has been a trend of increasing harmfulness of alternariosis or brown spot of pomegranate bushes (Alter-naria alternata (Fr.) Keissl.) in the western part of Azerbaijan. As our research results show, brown spot mainly affected the leaves of pomegranate bushes. Damage to pomegranate fruits differed only in certain years in the studied gardens. During field studies, it was found that the 0.4% fungicide Selphate gives the best results.

Unveiling the germination patterns of Alternaria porri (Ellis) by using regression analysis and hydrothermal time modeling

Purple blotch disease is a major fungal disease of Allium cepa L. plants which is caused by the fungus Alternaria porri. The best conditions for the growth of Alternaria porri are temperatures between 22 °C and 25 °C and relatively high humidity. The Hydrotime, Thermal Time, and Hydrothermal Time models were used to measure different parameters of seed germination; therefore, we used them to measure the interactive effects of temperature and water potential on the germination conidia of Alternaria porri. The laboratory experiments were carried out at five constant temperatures, between 5 and 30 °C, and five different water potentials between 0 MPa and − 6 MPa. The germination of Alternaria porri conidia was highest at 25 °C and 0 MPa and lowest at 5 °C and − 6 MPa. The percentage of conidia germination decreased rapidly after 25 oC. Conidia germination was also affected by different water potentials, decreasing at lower water potential. Models based on HTT showed a reasonable fit to the germination and growth rate datasets. The best fitting model for conidia germination (R2 = 0.98491) was based on variable base and maximum temperature as a function of water potential. Based on the TT, HT, and models, the highest and lowest values for θT1 were observed at -6.0 MPa at 30 °C, and 0 MPa at 5 °C and the highest and lowest θT2 values were recorded at -6.0 MPa at 5 °C and 0 MPa at 30 °C while the lowest and highest θH values were recorded at -6.0 MPa at 5 °C and 0 MPa at 25 °C, respectively, for the HTT model, the predicted θHTT average value is 16.32 (MPa°Ch-1). Based on the statistical analysis, the cardinal hydrothermal time constant (θHTT) accurately explains the interactive effect of T and Ψ on the germination of Alternaria porri conidia under different environmental conditions.

Fungi Associated with Olive Tree (cv. 'Nocellara del Belice') Decay in Trapani Province (Sicily, Italy).

Recently, in several locations in the province of Trapani (Sicily, Italy), olive growers have reported cases of decaying olive trees of cv. 'Nocellara del Belice', showing symptoms of defoliation, branch drying, xylem browning, and reduced production. Internal symptoms include white and brown wood rot, starting from the base of the trunk. These alterations have been observed in trees irrigated using a pipe system at the trunk with spray sprinklers. To identify the causal agents of decay, some trees were eradicated and dissected, and woody samples were processed to isolate and identify the associated fungal micro-organisms. The most common colonies were identified using morphological (macro- and microscopical observation) and molecular (PCR amplification of the rDNA-ITS region) analyses. Nine fungal taxa were identified, of which four were associated with this decay syndrome (Coriolopsis gallica, Fomitiporia mediterranea, Kirschsteiniothelia sp., and Pleurostoma richardsiae), three were considered ubiquitous and opportunistic fungi (Alternaria spp., Aspergillus amstelodami, and Trichoderma sp.), and the other two were mycelia sterilia. Artificial inoculation satisfied Koch's postulates, confirming the pathogenicity of the aforementioned fungi, even though the infections in the fields seem to be related to the irrigation system. This hypothesis would seem to be confirmed by the progression of decay over time in the trees subjected to the irrigation system described but not reported in olive groves differently managed. It is therefore considered appropriate to conduct further and more in-depth investigations aimed at studying the correlation between the irrigation system, presence of fungal agents, and manifestation of the syndrome. A further ongoing investigation is aimed at the use of biostimulants (Agrusaver, Savory Sun, VA LLC) on symptomatic trees, with the aim of both improving the vegetative performance of the host and limiting the symptoms detected in the field.

Novel Aminocoumarin-Based Schiff Bases: High Antifungal Activity in Agriculture.

Structural modification is an effective way to improve the antifungal activity of natural products and has been widely used in the development of novel fungicides. In this work, a series of aminocoumarin-based Schiff bases were synthesized and characterized by 1H-NMR, 13C NMR and HR-MS spectra. The in vitro inhibition activity of all compounds was tested against four phytopathogenic fungi (Alternaria solani, Fusarium oxysporum, Botrytis cinerea, and Alternaria alternata) using the mycelial growth rate method. The results showed that most of the target compounds exhibited significant antifungal activities. In particular, compounds 5b, 5c, 5d, 5h, 5n, 7c, 7n, and 7p exhibited more effective antifungal activity than commercially available fungicides, chlorothalonil and azoxystrobin. The structure-activity relationship revealed that the electron-withdrawing groups with more electronegativity introduced at the C-3 position were effective in improving the inhibitory activity and that halogenated benzaldehydes would be necessary in the preparation of Schiff bases. The compound 5n against Fusarium oxysporum (EC50=8.73 μg/mL) and the compound 7p against Alternaria alternata (EC50=26.25 μg/mL) were much better than the positive controls (chlorothalonil and azoxystrobin). Therefore, compounds 5n and 7p could serve as promising lead compounds for the development of novel broad-spectrum fungicides, which could be useful for applications in the agriculture.

The Effects of swnH1 Gene Function of Endophytic Fungus Alternaria oxytropis OW 7.8 on Its Swainsonine Biosynthesis.

The swnH1 gene in the endophytic fungus Alternaria oxytropis OW 7.8 isolated from Oxytropis glabra was identified, and the gene knockout mutant ΔswnH1 was first constructed in this study. Compared with A. oxytropis OW 7.8, the ΔswnH1 mutant exhibited altered colony and mycelium morphology, slower growth rate, and no swainsonine (SW) in mycelia, indicating that the function of the swnH1 gene promoted SW biosynthesis. Five differential expressed genes (DEGs) closely associated with SW synthesis were identified by transcriptomic analysis of A. oxytropis OW 7.8 and ΔswnH1, with sac, swnR, swnK, swnN, and swnH2 down-regulating. Six differential metabolites (DEMs) closely associated with SW synthesis were identified by metabolomic analysis, with P450, PKS-NRPS, saccharopine, lipopolysaccharide kinase, L-PA, α-aminoadipic, and L-stachydrine down-regulated, while L-proline was up-regulated. The SW biosynthetic pathways in A. oxytropis OW 7.8 were predicted and refined. The results lay the foundation for in-depth exploration of the molecular mechanisms and metabolic pathways of SW synthesis in fungi and provide reference for future control of SW in locoweeds, which would benefit the development of animal husbandry and the sustainable use of grassland ecosystems.

Rice husk biochar is more effective in blocking the cadmium and lead accumulation in two Brassica vegetables grown on a contaminated field than sugarcane bagasse biochar.

Heavy metal-contaminated soil has a great impact on yield reduction of vegetable crops and soil microbial community destruction. Biochar-derived waste biomass is one of the most commonly applied soil conditioners in heavy metal-contaminated soil. Different heavy metal-contaminated soil added with suitable biochars represent an intriguing way of the safe production of crops. This study investigated the effects of two types of biochar [rice husk biochar (RHB) and sugarcane bagasse biochar (SBB)] on Cd and Pb accumulation in Shanghaiqing (SHQ, a variety of Brassica campestris L.) and Fengyou 737 (FY, a variety of Brassica napus), as well as on the soil microbial community, through a field experiment. RHB and SBB were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmet-Teller method. The results showed that RHB and SBB displayed the higher pH, cation exchange capacity and pore properties, and the addition of RHB and SBB enhanced soil pH and rhizosphere microorganisms promoting vegetables yield. RHB treatments were more effective than SBB in reducing upward transfer of Cd and Pb, blocking the accumulation of Cd and Pb in the edible parts of SHQ and FY, and decreasing soil Cd and Pb bioavailability. Additionally, RHB and SBB changed the composition of the rhizosphere soil microbial community. The application of biochar promoted the growth of ecologically beneficial bacteria (Nitrospira, Opitutus, and Gemmatimonas) and fungi (Mortierella and Holtermanniella), whereas reducing the enrichment of plant pathogenic fungi (Alternaria, Stagonosporopsis, Lectera, and Periconia) in rhizosphere soil. Our findings demonstrated that the application of RHB significantly reduces Cd and Pb accumulation in the edible parts by decreasing the soil Cd and Pb bioavailability and altering the rhizosphere microbial community composition in two Brassica vegetables grown on Cd/Pb-contaminated soils. Thus, the application of two biochar, especially RHB is a feasible strategy for the safe production of vegetable crops in Cd/Pb co-contaminated soils.

Complete genome sequence of a novel mitovirus identified in the phytopathogenic fungus Alternaria tenuissima.

In this study, a novel positive-sense single-stranded RNA (+ ssRNA) mycovirus, Alternaria tenuissima mitovirus 1 (AtMV1), was identified in Alternaria tenuissima strain YQ-2-1, a phytopathogenic fungus causing leaf blight on muskmelon. The genome of AtMV1 is a single RNA molecule that is 3013 nt in length with an A + U content of 66.58% and contains a single open reading frame (ORF) using the fungal mitochondrial genetic code. The ORF was predicted to encode a 313-amino-acid RNA-dependent RNA polymerase (RdRp) with a molecular mass of 35.48 kDa, which contains six conserved motifs with the highly conserved GDD tripeptide in motif IV. The 5' and 3' untranslated regions were predicted to fold into stem-loop and panhandle secondary structures. The results of a BLASTp search revealed that the amino acid (aa) sequence of RdRp of AtMV1 shared the highest sequence similarity (51.04% identity) with that of Sichuan mito-like virus 30, a member of the genus Duamitovirus within the family Mitoviridae. Phylogenetic analysis based on the aa sequence of the RdRp suggested that AtMV1 is a novel member of the genus Duamitovirus. To our knowledge, this is the first report of the complete genome sequence of a new mitovirus infecting A. tenuissima.