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.

Response of Alternaria and Fusarium Species to Low Precipitation in a Drought-Tolerant Plant in Morocco.

The plant mycobiome plays a crucial role in the host life cycle, influencing both healthy and diseased states, and is essential for plant tolerance to drought. In this study, we used ITS metabarcoding to investigate the fungal community of the drought-resistant plant Malva sylvestris L. in Morocco along a gradient of precipitation, encompassing subhumid and semi-arid environments. We sampled three biotopes: rhizosphere, bulk soil, and root endosphere. Our findings revealed an absence of beta-diversity differences between bulk soil and rhizosphere, indicating that the plant does not selectively influence its rhizosphere mycobiome. Additionally, ASVs belonging to the genus Alternaria represented up to 30% of reads in the plant's roots and correlated with drought (p = 0.006), indicating a potential role for this fungal genus in mitigating drought, possibly as part of the dark septate endophyte group. Root staining and microscopic observation revealed extensive colonization by fungal hyphae and microsclerotia-like structures. Furthermore, ASVs identified as Fusarium equiseti were also correlated with low precipitation and recognized as a hub taxon in the roots. However, it remains uncertain whether this species is pathogenic or beneficial to the plant. These insights contribute to our understanding of the plant mycobiome's role in drought tolerance and highlight the importance of specific fungal taxa in supporting plant health under varying environmental conditions. Future research should focus on characterizing these taxa's functional roles and their interactions with the host plant to further elucidate their contributions to drought resistance.

Synthesis of Indolyl Isothiocyanate and Its Inhibitory Activity against Fungi.

Based on previous research, this study synthesized 24 compounds by splicing the substructures of the indolyl group and the isothiocyanate group. Alternaria alternata, Phytophthora capsici, Botrytis cinerea, and Valsa mali were used to test the activity of the target compounds. At 100 µg/mL, compounds 8, 13, 14, and 17 exhibited excellent inhibitory effects of more than 80% on P. capsici, B. cinerea, and V. mail. The EC50 values of compounds 13 and 14 were 0.64 and 2.08 µg/mL, respectively. Potted antifungal activity demonstrated that compounds 13 and 14 had a protective effect of around 80% against B. cinerea at 200 µg/mL. Further physiological and biochemical studies on B. cinerea revealed that compound 13 thickened cell walls and caused mitochondrial vacuolization. Moreover, theoretical calculations indicated that the charge distribution of indolyl isothiocyanate compounds played a crucial role in the observed fungicidal activity. In summary, this study provided fundamental reference data for the derivative synthesis of these indolyl isothiocyanate compounds.

Design, Synthesis, Antifungal Evaluation, and Three-Dimensional Quantitative Structure-Activity Relationship of Novel 5-Sulfonyl-1,3,4-thiadiazole Flavonoids.

Plant pathogenic fungi frequently disrupt the normal physiological and biochemical functions of plants, leading to diseases, compromising plant health, and ultimately reducing crop yield. This study aimed to address this challenge by identifying antifungal agents with innovative structures and novel mechanisms of action. We designed and synthesized a series of flavonoid derivatives substituted with 5-sulfonyl-1,3,4-thiadiazole and evaluated their antifungal activity against five phytopathogenic fungi. Most flavonoid derivatives demonstrated excellent antifungal activity against Botrytis cinerea (B. cinerea), Alternaria solani (A. solani), Rhizoctorzia solani (R. solani), Fusarium graminearum (F. graminearum), and Colletotrichum orbiculare (C. orbiculare). Specifically, the EC50 values of 38 target compounds against R. solani were below 4 µg/mL, among which the compounds C13 (EC50 = 0.49 µg/mL), C15 (EC50 = 0.37 µg/mL), and C19 (EC50 = 0.37 µg/mL) had the most prominent antifungal activity, superior to that of the control drug carbendazim (EC50 = 0.52 µg/mL). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the cellular ultrastructures of R. solani mycelia and cells after treatment with the compound C19 revealed sprawling growth of hyphae, a distorted outline of their cell walls, and reduced mitochondrial numbers. Studying the 3D-QSAR between the molecular structure and antifungal activity of 5-sulfonyl-1,3,4-thiadiazole-substituted flavonoid derivatives could significantly improve conventional drug molecular design pathways and facilitate the development of novel antifungal leads.

The Antiphytopathogenic Metabolites and the Synergy of Endophytes Paraphaeosphaeria sp., Nigrospora oryzae from the Same Ginkgo biloba Host.

Two endophytes from the same Ginkgo biloba host were isolated and cultured separately. Three new eremophilane sesquiterpenoids (1-3), three new furan derivates (6, 8-9), one new polyketide (10), and four known compounds (4, 5, 7, 11) from Paraphaeosphaeria sp. and two new 10-membered macrolides (12-13), a new liner polyketide (14), a new benzofuran (15), and six known compounds (16-21) from Nigrospora oryzae were isolated. The structures of the isolated compounds were determined by spectroscopic methods, NMR calculations, and ECD calculations. The compounds 3-7, 9-10, 12, and 14-17 showed significant antiphytopathogenic effects against mycotoxigenic Alternaria sp. comparable to the activity of nystatin (positive control). Compounds 2, 6, 8, 9, and 18 indicated inhibitions against phytopathogen Fusarium asiaticum with MICs < 10 µg/mL. In addition, the compounds with weak antifungal activities from two endophytes were mixed to test their antifungal activity. The results showed that the metabolites from two endophytes had synergistic antifungal effects, and the beneficial interactions between natural products can induce more antifungal effects against plant pathogens than that of single compounds.

First Investigation of Secondary Metabolites from Aspergillus xerophilus Reveals Compounds with Inhibitive Effects against Three Phytopathogenic Fungi of Agrarian Crops.

Fungal secondary metabolites play a highly significant role in crop protection, which is related to their antifungal activity against agriculturally important phytopathogens. In fact, plant diseases caused by fungi including species belonging to the genera of Alternaria, Botrytis, and Fusarium have become increasingly serious affecting crop yield and quality. Hence, there is increasing awareness by the scientific community of the importance of exploiting fungal products for finding new compounds able to inhibit phytopathogens. In this study several drimane-type sesquiterpenes have been detected for the first time as products of Aspergillus xerophilus by GC-MS analysis of the organic extracts obtained from the mycelia and culture filtrates of the fungus grown on two different substrates. Seven pure drimane-type sesquiterpenes were also isolated and identified by spectroscopic methods. The inhibitory effects of the pure compounds have been investigated against three phytopathogenic fungi of agrarian crops (i.e., Botrytis cinerea, Alternaria alternata, and Fusarium oxysporum f. sp. pisi). Among the drimane-type sesquiterpenes isolated in this study, 9,11-dihydroxy-6-oxodrim-7-ene is the most active against the three phytopathogens. Our findings also reveal the high sensitivity of A. alternata to the isolated compounds. These results pave the way for future applications in agriculture of both A. xerophilus and its metabolites.

Detoxification Mechanism of Hinokitiol by Alternaria alternata and Its Application in Agricultural Antifungal Control.

Alternaria alternata is a common plant pathogen that can infect crops and reduce their production. In this work, an antagonism experiment between A. alternata and the essential oil of arborvitae (Platycladus orientalis) was performed, and it was proven that A. alternata had developed resistance to this plant-derived fungicide. A. alternata facilitated the biotransformation of hinokitiol (1), the main antifungal compound in the essential oil of arborvitae, into (R)-2-hydroxy-ß-methylbenzeneethanol (2), which does not have antifungal activity against A. alternata. This biotransformation is an unusual ring-contraction reaction that was verified to be catalyzed by P450 enzyme hydroxylation and Baeyer-Villiger oxidation. In addition, the P450 enzyme inhibitors 1-aminobenzotriazole and piperonyl butoxide effectively prevented the destruction of the hinokitiol structure by A. alternata, and the combined use of these P450 enzyme inhibitors significantly increased the antifungal activity of hinokitiol. This work provides a theoretical reference for the further development of botanical fungicides.

Design, Bioactivity, and Action Mechanism of Pyridinecarbaldehyde Phenylhydrazone Derivatives with Broad-Spectrum Antifungal Activity.

Replacing old pesticides with new pesticide varieties has been the main means to solve pesticide resistance. Therefore, it is necessary to research and develop new antifungal agents for plant protection. In this study, a series of pyridinecarbaldehyde phenylhydrazone derivatives were designed and evaluated for their inhibition activity on plant pathogenic fungi to search for novel fungicide candidates. Picolinaldehyde phenylhydrazone (1) and nicotinaldehyde phenylhydrazone (2) were identified as promising antifungal lead scaffolds. The 4-fluorophenylhydrazone derivatives (1a and 2a) of 1 and 2 showed highly effective and broad-spectrum inhibition activity in vitro on 11 phytopathogenic fungi with EC50 values of 0.870-3.26 µg/mL, superior to the positive control carbendazim in most cases. The presence of the 4-fluorine atom on the phenyl showed a remarkable activity enhancement effect. Compound 1a at 300 µg/mL provided almost complete protection against infection of Alternaria solani on tomatoes over the post-treatment 9 days and high safety to germination of plant seeds. Furthermore, 1a showed strong inhibition activity with an IC50 value of 0.506 µg/mL on succinate dehydrogenase in A. solani. Molecular docking showed that both 1a and 2a can well bind to the ubiquinone-binding region of SDH by the conventional hydrogen bond, carbon-hydrogen bond, π-π or π-amide interaction, π-alkyl interaction, X---F (X = N, C, or H) interaction, and van der Waal forces. Meanwhile, scanning and transmission electron analysis displayed that 1a destroyed the morphology of mycelium and the structure of the cell membrane of A. solani. Fluorescent staining analysis revealed that 1a changed the mitochondrial membrane potential and cell membrane permeability. Thus, pyridinecarbaldehyde phenylhydrazone compounds emerged as novel antifungal lead scaffolds, and 1a and 2a can be considered promising candidates for the development of new agricultural fungicides.

Transcriptomic analysis unveils alterations in the genetic expression profile of tree peony (Paeonia suffruticosa Andrews) infected by Alternaria alternata.

BACKGROUND: Black spot disease in tree peony caused by the fungal necrotroph A. alternata, is a primary limiting factor in the production of the tree peony. The intricate molecular mechanisms underlying the tree peony resistance to A. alternata have not been thoroughly investigated. RESULTS: The present study utilized high-throughput RNA sequencing (RNA-seq) technology to conduct global expression profiling, revealing an intricate network of genes implicated in the interaction between tree peony and A. alternata. RNA-Seq libraries were constructed from leaf samples and high-throughput sequenced using the BGISEQ-500 sequencing platform. Six distinct libraries were characterized. M1, M2 and M3 were derived from leaves that had undergone mock inoculation, while I1, I2 and I3 originated from leaves that had been inoculated with the pathogen. A range of 10.22-11.80 gigabases (Gb) of clean bases were generated, comprising 68,131,232 - 78,633,602 clean bases and 56,677 - 68,996 Unigenes. A grand total of 99,721 Unigenes were acquired, boasting a mean length of 1,266 base pairs. All these 99,721 Unigenes were annotated in various databases, including NR (Non-Redundant, 61.99%), NT (Nucleotide, 45.50%), SwissProt (46.32%), KEGG (Kyoto Encyclopedia of Genes and Genomes, 49.33%), KOG (clusters of euKaryotic Orthologous Groups, 50.18%), Pfam (Protein family, 47.16%), and GO (Gene Ontology, 34.86%). In total, 66,641 (66.83%) Unigenes had matches in at least one database. By conducting a comparative transcriptome analysis of the mock- and A. alternata-infected sample libraries, we found differentially expressed genes (DEGs) that are related to phytohormone signalling, pathogen recognition, active oxygen generation, and circadian rhythm regulation. Furthermore, multiple different kinds of transcription factors were identified. The expression levels of 10 selected genes were validated employing qRT-PCR (quantitative real-time PCR) to confirm RNA-Seq data. CONCLUSIONS: A multitude of transcriptome sequences have been generated, thus offering a valuable genetic repository for further scholarly exploration on the immune mechanisms underlying the tree peony infected by A. alternata. While the expression of most DEGs increased, a few DEGs showed decreased expression.

Study on the Bioactivity, Toxicity, Stereoselective Fate, and Risk Assessment of Chiral Fungicide Isopyrazam in Five Kinds of Fruits and Vegetables.

Isopyrazam (IPZ) is a new chiral fungicide. For bioactivity, there was a 3.37-1578 times difference among the four stereoisomers. For Alternaria alternata and Phoma multirostrata, cis-(1S,4R,9S)-IPZ had the greatest activity. Using cis-IPZ might improve the efficacy and reduce the dosage of the racemate by 54.7-72.2% for A. alternata and P. multirostrata. To zebrafish, trans-IPZ showed the highest acute toxicity (LC50, 0.096 mg/L). The degradation half-lives of IPZ stereoisomers in the five crops ranged from 3.50 to 15.2 days. Cis-IPZ was preferentially degraded in grape, pear, and celery. The residual concentrations of IPZ in grape and celery were still higher than the maximum residue limit, and the acute and chronic dietary intake risks of IPZ in celery were unacceptable (RQa: 146-250%, HQ: 117-200%), which were worthy of further researching. Based on the research results, it is safer and more reasonable to use IPZ in the form of a racemate with a high ratio of cis-IPZ.

Integrated Transcriptome and Metabolome Analysis Revealed the Key Role of the Flavonoid Biosynthesis in Olive Defense Against Alternaria alternata.

The olive tree is an important oil woody plant with high economic value, yet it is vulnerable to the attack of numerous fungi. The successful control of olive fungal diseases requires a comprehensive understanding of the disease resistance mechanisms in plants. Here, we isolated Alternaria alternata from the diseased leaves of olive plants, and screened a resistant ("Leccino") and susceptible ("Manzanilla de Sevilla") cultivar from eight olive cultivars to explore their resistance mechanisms. Transcriptomic and metabolomic analyses identified the flavonoid biosynthesis as a key defense pathway against A. alternata. Five important transcription factors associated with flavonoid biosynthesis were also determined. The overexpression of OeWRKY40 significantly enhanced the disease resistance of the susceptible cultivar and upregulated the expression of genes involved in flavonoid biosynthesis and the accumulation of related metabolites. LUC assays further proved that OeWRKY40 can activate the expression of OeC4H. These results help to better clarify the molecular mechanisms of flavonoid biosynthesis against A. alternata. Our study provides key information for further exploration of the molecular pathways of olive plants and their resistance to fungi, an important factor for molecular breeding and utilization of resistant cultivars.

Co-Occurrence of Fusarium and Alternaria Metabolites in Brewing Barley Monitored during Two Consecutive Years (2019-2020).

Known mycotoxins have been investigated for years. They have been included in legislation and are meticulously controlled in most cereals, cereal-related products, and raw materials of animal origin. However, there are still mycotoxins that need to be addressed by regulations and subsequently are not monitored but can still occur in relatively high concentrations. This research aimed to assess the occurrence of common Fusarium mycotoxins in hulled barley. Samples of hulled barley were treated in the field with two protective treatments, alongside a control sample sans treatment. Furthermore, we aimed to assess the occurrence of Alternaria mycotoxins in the chosen samples. The results have shown that Fusarium mycotoxins were mostly determined by climatic conditions (no mycotoxins in 2020, except siccanol). Most interesting was the appearance of infectopyron, an Alternaria toxin that was detected in all samples in 2019 and in the majority of samples in 2020. The highest concentration was detected in 2019 in hulled barley with 536 µg/kg, while in 2020, the highest concentration of this mycotoxin reached 350 µg/kg. These findings depict the need for further research on food safety regarding mycotoxins, and the need for additional changes in legislation. This investigation shows that fungicide application in rainy years cannot efficiently suppress mycotoxin production. Additionally, even in dry years, some of the mycotoxins not involved in legislation, such as infectopyron and siccanol, do not respond to the application of fungicides.

Study on the Effectiveness of a Copper Electrostatic Filtration System "Aerok 1.0" for Air Disinfection.

BACKGROUND: Bioaerosols can represent a danger to health. During SARS-CoV-2 pandemic, portable devices were used in different environments and considered a valuable prevention tool. This study has evaluated the effectiveness of the air treatment device "AEROK 1.0®" in reducing microbial, particulate, and pollen airborne contamination indoors, during normal activity. METHODS: In an administrative room, airborne microbial contamination was measured using active (DUOSAS 360 and MD8) and passive sampling; a particle counter was used to evaluate particle concentrations; a Hirst-type pollen trap was used to assess airborne pollen and Alternaria spores. Statistical analysis was performed using SPSS 26.0; p values < 0.05 were considered statistically significant. RESULTS: The airborne bacterial contamination assessed by the two different samplers decreased by 56% and 69%, respectively. The airborne bacterial contamination assessed by passive sampling decreased by 44%. For fungi, the reduction was 39% by active sampling. Airborne particles (diameters ≥ 1.0, 2.0 µm) and the ratio of indoor/outdoor concentrations of total pollen and Alternaria spp. spores significantly decreased. CONCLUSIONS: The results highlight the effectiveness of AEROK 1.0® in reducing airborne contamination. The approach carried out represents a contribution to the definition of a standardized model for evaluating the effectiveness of devices to be used for air disinfection.

Association of water stress and Fusarium solani exacerbated Dalbergia sissoo dieback disease.

Globally, there is a growing concern about tree mortality due to harsh climates and changes in pest and disease patterns. However, experimental studies on the interactions between biotic and abiotic stresses in plants are relatively scarce. In this study, we investigated the interaction between Fusarium solani and water-stressed Dalbergia sissoo saplings. We postulated that under drought conditions, sissoo plants would become more susceptible to dieback infestation. Five fungi, including Fusarium oxysporum, Curvularia lunata, Cladophialophora carrionii, Alternaria alternaria, and Fusarium solani, were isolated from an old shisham tree showing advanced symptoms of dieback infestation. These fungi were identified based on their ITS sequence homology and spore characteristics. Dieback development was more pronounced in plants experiencing water stress, regardless of their predisposition or whether it occurred simultaneously. Lesions were more noticeable and longer in predisposed saplings (3.8cm), followed by simultaneous (2.4cm) and much smaller lesions in seedlings that were inoculated and well-watered (0.24cm). Progressive browning of the upper leaves, which lowers sapling height in predisposed, simultaneous, and well-watered inoculated saplings to 8.09 inches, 5.93 inches, and 17.42 inches, are typical dieback symptoms. Water stress causes the loss of chlorophyll a, b, and carotenoids, which reduces stomatal conductance, transpiration rate, and photosynthetic activity, leading to poor development and mortality. Similarly, predisposed, simultaneous, and well-watered inoculated seedlings expressed increased activity of CAT (22.57, 18.148, and 9.714 U/mg) and POD (3.0, 4.848, 1.246 U/mg), to reduce the damage caused by elevated levels of H2O2 expression. It is concluded that water stress is the main cause of dieback in shisham saplings that subsequently disposed of infected seedlings to secondary agents such as fungi and insects in the advanced stages of the dieback with prolonged drought stress. The lack of dieback in native populations is attributed to the absence of several ecological stresses, including water stress, extended droughts, waterlogging, and salinity. This study emphasizes the need for additional research into the effects of abiotic factors linked with fungal diseases on the long-term production and management of D. sissoo in Pakistan.

Preliminary Identification of Macroconidia (Asexual Forms) of Alternaria Species in Histologic Tissue Sections in a Post Covid Patient with Allergic Fungal Rhinosinusitis.

To document a case of `preliminary` identification of Alternaria sp (a phaeohyphomycotic agent) based on morphology in tissue section in a patient with allergic fungal rhinosinusitis. A 25-year-old male, a known asthmatic in a post Covid -19 state, presented with headache, facial swelling and nasal block with discharge of brownish mucoid material. Debrided material from the right maxillary antrum and middle turbinate showed brownish mucoid material admixed with firm to hard degenerated bony spicules sent in formalin and subjected for histopathological examination. Histopathology showed fragments of tissue, mucoid material, degenerated bony spicules, and blood clots. Amidst ulcerated epithelium and mucoid debris were seen scattered pigmented fungi in a state of `vegetative sporulation` with characteristic brownish multicellular `macroconidia` diagnostic of Alternaria sp. A diagnosis of `Phaeohyphomycosis` possibly due to Alternaria sp was offered. The patient was treated with Amphotericin B. The patient was lost to follow up. Clinical materials such as tissue sections or smears from nasal mucus secretions in cases of allergic fungal rhinosinusitis provide a very good source for `preliminary` identification of species and early institution of therapy while waiting for the fungal culture report.

Activity of Streptomyces globosus OPF-9 against the important pathogen Alternaria longipes and biocontrol mechanisms revealed by multi-omic analyses.

Plant diseases caused by fungal pathogens represent main threats to the yield and quality of agricultural products, and Alternaria longipes is one of the most important pathogens in agricultural systems. Biological control is becoming increasingly prevalent in the management of plant diseases due to its environmental compatibility and sustainability. In the present study, a bacterial strain, designated as OPF-9, was shown to effectively inhibit the pathogen A. longipes, which was identified as Streptomyces globosus. The culture conditions for OPF-9 were optimized through a stepwise approach and the fermentation broth acquired displayed an excellent inhibitory activity against A. longipes in vitro and in vivo. Further investigations suggested that the fermentation broth exhibited strong stability under a range of adverse environmental conditions. To reveal the molecular bases of OPF-9 in inhibiting pathogens, the whole-genome sequencing and assembly were conducted on this strain. It showed that the genome size of OPF-9 was 7.668 Mb, containing a chromosome and two plasmids. Multiple clusters of secondary metabolite synthesis genes were identified by genome annotation analysis. In addition, the fermentation broth of strain OPF-9 was analyzed by LC-MS/MS non-target metabolomic assay and the activity of potential antifungal substances was determined. Among the five compounds evaluated, pyrogallol displayed the most pronounced inhibitory activity against A. longipes, which was found to effectively inhibit the mycelial growth of this pathogen. Overall, this study reported, for the first time, a strain of S. globosus that effectively inhibits A. longipes and revealed the underlying biocontrol mechanisms by genomic and metabolomic analyses.

Withania somnifera osmotin (WsOsm) confers stress tolerance in tobacco and establishes novel interactions with the defensin protein (WsDF).

Pathogenesis-related proteins (PR), including osmotins, play a vital role in plant defense, being activated in response to diverse biotic and abiotic stresses. Despite their significance, the mechanistic insights into the role of osmotins in plant defense have not been extensively explored. The present study explores the cloning and characterization of the osmotin gene (WsOsm) from Withania somnifera, aiming to illuminate its role in plant defense mechanisms. Quantitative real-time PCR analysis revealed significant induction of WsOsm in response to various phytohormones e.g. abscisic acid, salicylic acid, methyl jasmonate, brassinosteroids, and ethrel, as well as biotic and abiotic stresses like heat, cold, salt, and drought. To further elucidate WsOsm's functional role, we overexpressed the gene in Nicotiana tabacum, resulting in heightened resistance against the Alternaria solani pathogen. Additionally, we observed enhancements in shoot length, root length, and root biomass in the transgenic tobacco plants compared to wild plants. Notably, the WsOsm- overexpressing seedlings demonstrated improved salt and drought stress tolerance, particularly at the seedling stage. Confocal histological analysis of H2O2 and biochemical studies of antioxidant enzyme activities revealed higher levels in the WsOsm overexpressing lines, indicating enhanced antioxidant defense. Furthermore, a pull-down assay and mass spectrometry analysis revealed a potential interaction between WsOsm and defensin, a known antifungal PR protein (WsDF). This suggests a novel role of WsOsm in mediating plant defense responses by interacting with other PR proteins. Overall, these findings pave the way for potential future applications of WsOsm in developing stress-tolerant crops and improving plant defense strategies against pathogens.

Genomic and Chemical Evidence on Biosynthesis of Taxane Diterpenoids in Alternaria Isolates from Cupressaceae.

Alternaria species (Deuteromycetes, Ascomycota) as ubiquitous fungi and prolific producers of a variety of toxic compounds are a part of microbiomes of plants, humans, and animals, mainly causing disease, allergic reactions, and toxicosis. However, some species have also been reported as endophytic microorganisms with highly bioactive metabolites. Our previous results indicate that potentially endophytic Alternaria species from Cupressaceae produce bioactive metabolites that possibly contribute to plant holobiont's health. Here, a possible mechanism behind this bioactivity is elucidated. As some endophytic fungi are reported to produce cytotoxic taxane diterpenoids, eight potentially endophytic Alternaria isolates from our collection were analyzed for the presence of the key genes of the paclitaxel (Taxol) biosynthetic pathway, i.e., taxadin synthase (ts), 10-deacetylbaccatin III-10-O-acetyltransferase (dbat), and C-13-phenylpropanoid side-chain CoA acyltransferase (bapt). The presence of all genes, i.e., ts, dbat, and bapt, was detected by PCR in six isolates and dbat and bapt in two isolates. Chemical analyses of the fermentation broths by TLC and HPLC chromatography and IR spectroscopy indicated the synthesis of the final product, i.e., paclitaxel. So, we introduce the synthesis of taxane diterpenoids as a possible mechanism by which Alternaria occupies the plant niches and protects the plant holobiont in the presence of competing microorganisms.

The fate of Alternaria toxin tenuazonic acid (TeA) during the processing chain of wheat flour products and risk control strategies for mycotoxins.

The fate of Alternaria toxin tenuazonic acid (TeA) during the processing chain of wheat flour products was systemically evaluated. TeA was analyzed by liquid chromatography-mass spectrometry (LC-MS/MS) in wheat grains and the corresponding wheat flour products produced throughout the whole chain. The results indicated that TeA contamination in wheat grains largely determines the level of TeA toxin present in byproducts, semi-finished products, and finished products of the processing of four types of simulated processed wheat flour products (e.g., dry noodles, steamed breads, baked breads, and biscuits). The different food processing techniques had different effects on the fate of TeA. Wheat flour processing can reduce the TeA content in wheat grains by 58.7-83.2 %, indicating that wheat flour processing is a key step in reducing the TeA content in the food chain. Among the four types of wheat flour products, the decreases in TeA content in biscuits (69.8-76.7 %) were greater than those in dry noodles (15.5-22.3 %) and steamed breads (24.9-43.6 %). In addition, the decreasing effect of TeA was especially obvious in the wheat flour product chain with a high level of contamination. The processing factors (PFs) for TeA were as low as 0.20 for the four wheat processing methods and as high as 1.24 for the dry noodle processing method. At the average and 95th percentiles, dietary exposure to TeA in Chinese consumers including infants and young children did not exceed the relevant threshold value of toxicological concern (TTC) of TeA (1.5 µg/kg body weight per day), indicating an acceptable health risk for Chinese consumers via wheat flour products. These findings provide new insight into the fate of TeA in the food chain and mycotoxin control on the safety of wheat flour products and public health.