Terrestrial plant resources are becoming increasingly scarce; moreover, the development of science and technology has facilitated the exploration of marine ecosystems. We isolated and identified six novel (1–6) and six (7–12) known secondary metabolites of Alternaria sp MCCC 3A00467 by chromatographic and spectroscopic techniques and investigated their antitumor activities in human myeloma (U266), liver cancer (HepG2), and lung cancer (A549) cells by the MTT assay. Among these compounds, the new compounds 2, 3 and 4 exhibited excellent anticancer activities with IC₅₀ values of 21.98, 24.99 and 14.78 μg/mL, respectively. These compounds obtained from a marine source have the potential to be developed into novel anticancer drugs.

Celtis sinensis is an adaptable species that is widely grown in southern China. In June 2022, a leaf blotch disease of C. sinensis was observed in Nanjing, Jiangsu, China. Based on morphological characterization, three isolates were identified as Alternaria species. Phylogenetic analysis of combined ITS, GAPDH, TEF1-α, RPB2 and Alt a 1 sequences identified the three isolates we obtained as Alternaria alternata and Alternaria koreana. Koch’s postulates were fulfilled in the greenhouse, and the pathogenicity of A. alternata and A. koreana was determined by leaf inoculation tests on C. sinensis seedlings. The symptoms of indoor inoculation were consistent with those in the field. A. alternata and A. koreana can grow at 15-35 °C, with an optimal growth temperature of 25 °C. The results of fungicide sensitivity experiments indicated that A. alternata and A. koreana were the most sensitive to prochloraz, which may be a useful strategy for the future prevention and control management of A. alternata and A. koreana. This study provides the first step for further research on A. alternata and A. koreana as pathogens of C. sinensis and provides a theoretical basis for future control strategies.

Seeds play a vital role in the perpetuation of plant species, both in natural environments and agriculture. However, they often face challenges from biotic stresses, such as seedborne pathogenic fungi. The transgenerational transmission of these seedborne fungi, along with their dissemination during seed commercialization, can contribute to the emergence of global epidemic diseases, resulting in substantial economic losses. One such pathogenic fungus is Alternaria brassicicola, responsible for causing black spot disease in Brassicaceae. This necrotrophic seedborne fungus negatively impacts plant development, consequently affecting crop production and seed quality. To gain a deeper understanding of the interaction between seeds and necrotrophic fungi, the Arabidopsis thaliana/Alternaria brassicicola model pathosystem has been extensively studied. Recent transcriptomic and genetic studies revealed a distinctive immune response of seeds against this pathogen, divergent from the immune response described in the plant vegetative phase. In germinating seeds and seedlings, the necrotrophic fungus seems to induce susceptible response [1]. It was observed at the RNA level that to the detriment of jasmonic acid pathway, Alternaria induced the salicylic acid and glucosinolate (GSL) pathways. Genetic evidence identified that seedling necrosis, potentially beneficial to the growth of the necrotrophic agent, is hypersensitive response mediated by GSL pathway. Transmission of necrotrophic fungal from seed to seedling unveils novel regulations of the immune response, that would illustrate a trade-off between seedling establishment and fungal infection. This knowledge is promising to sustainably ensure the sanitary quality of crops.

Alternaria brown spot (ABS) is a disease caused by the fungus Alternaria alternata f. sp. citri, which results in lesions on fruits, leaves, and branches of several mandarin varieties and their hybrids. Due to the high cost of fungicide application, alternative methods for controlling ABS need to be studied. Therefore, this study aimed to evaluate the use of essential oils (EOs) from different mandarin varieties to mitigate the effects of ABS. The inhibitory effect of different concentrations (1, 2, 4, 8, and 16 μL mL-1) of Fremont IAC 543 mandarin, IAC 2019Maria mandarin, Murcott IAC 221 tangor, and Late IAC 855 willowleaf. EOs on the in vitro mycelial growth of the fungus A. alternata was evaluated. Additionally, the curative and preventive effects of these EOs on ABS symptoms on detached leaves of Murcott IAC 221 tangor were also assessed. The EO of IAC 2019Maria mandarin induced less mycelial growth, and consequently, greater inhibition of the growth of the fungus A. alternata at a concentration of 16 μL mL-1. This EO was more effective in control than the other oils tested. In the detached leaf experiment, both the curative and preventive treatments at a concentration of 16 μL mL-1 showed lower values of disease severity.

Most fungal species are commensals, not pathogenic for plants, humans, or animals. However, several species from genera Alternaria, Aspergillus, Trichophyton and Microsporum are common causes of disease, even for immunocompetent individuals, contributing to skin barrier impairment. A total of 68 allergic dogs were selected from a veterinary dermatology and allergy outpatient consultation, for conditions related to Malassezia overgrowth or other fungal complications. Allergy diagnosis was made through anamnestic and clinical criteria and allergy-implicated species were identified by intradermal testing (IDT) and serum determination of specific immunoglobulin E (sIgE). Dermatophagoides farinae, Dactylis glomerata and Malassezia pachydermatis showed as the higher sensitization species from each group. Significant correlations at p<0.05 were found between Dactylis glomerata and Phleum pratense grass pollens, Dermatophagoides farinae and Dermatophagoides pteronyssinus, Acarus siro, Tyrophagus putrescentiae and Lepidoglyphus destructor dust/storage mites, and between fungi like Aspergillus mix and Penicillium or Alternaria alternata. A significant correlation was also found between sensitization to Aspergillus mix and D. farinae, D. pteronyssinus or A. siro. Rather severe dermatitis was observed where positive IDT to Malassezia pachydermatis was found, regardless of the presence of circulating sIgE, allowing us to perceive the usefulness of both sIgE and IDT for allergy diagnosis to fungi.

Alternaria alternata is a saprophyte and is also known to cause many opportunistic infections in humans. Alternaria infections are important factors of morbidity and mortality in im-mune-compromised and solid organ transplant (SOT). Sensitivity to the airborne fungus Alter-naria alternata is also believed to be a common cause of allergic asthma. Therapies are limited by the lack of knowledge about the role of individual fungal gene products and symptoms in im-mune-compromised and transplant patients. This review summarizes the published case studies on Alternaria alternata infections in transplant patients.

Fungal spores are universal atmospheric components associated to allergic reactions. Alternaria (Ascomycota) is considered the most allergenic spore taxa. Alt a 1 is the major allergen of Alternaria and is present also in other Pleosporales. In this study, standard Hirst-based sampling and analyzing methods for measuring spore daily concentrations of Alternaria, Curvularia, Drechslera-Helminthosporium, Epicoccum, Leptosphaeria, Pithomyces, Pleospora and Stemphyllium (all included in the taxon Pleosporales) have been used besides two high-volume samplers, Burkard Cyclone (2017) and MCV CAV-A/mb (2019-2020), and ELISA Kits for measuring the allergen. The detection and quantification of Alt a 1 was only possible in the samples from the MCV sampler. Although Alt a 1 was better correlated with Alternaria spores than with Pleosporales spores, the three of them showed high correlations. It is shown, for the first time, a high and significant correlation of Alt a 1 with temperature, a negative one with relative humidity and no correlation with precipitation. The aerobiological monitoring of these three elements ensures the best information for understanding the affectation to allergy sufferers but, if not possible, as a minimum public health service aiming at the detection, treatment and prevention of allergy, the study of the airborne Alternaria spores should be ensured.

Plant pathogenic fungi are the most important cause of losses in agriculture. In the face of the overuse of synthetic fungicides, natural products are an encouraging alternative to control these plant pathogenic fungi. In this study, we tested the antifungal capacity of metabolites produced by strains of the genus Streptomyces against the plant pathogenic fungi Alternaria alternata, Botrytis cinerea and Fusarium oxysporum. In addition, we investigated the feasibility of applying these metabolites in a postharvest setting for the control of B. cinerea on cherry tomato fruits. The results revealed the ability of the strains, especially Streptomyces netropsis, to inhibit the growth of plant pathogenic fungi and, in some cases, the sporulation of these fungi. In addition, we observed an interesting phenomenon in which Streptomyces strains physically encapsulated the mycelium of the fungi, which contributed to their inhibition. Finally, the protective activity of S. netropsis extract on Cherry tomato fruits infected with B. cinerea was demonstrated. In conclusion, this research opens the door to studies on the understanding of physical microbial interactions in natural environments and holds promise in agriculture, especially in the protection of agricultural products during the post-harvest stage as a safer and more sustainable alternative.

This lack of information is due to the primary role of HSTs in fungal pathogenesis, which often masks the functions of NSTs and CWDEs. So, the toxic effects of A. alternata metabolites due to NSTs and CWDEs have received minor attention than those reported for HSTs mycotoxins [11]. A wider study of the activity of isolated fungal metabolites can allow the identification of compounds directly related to the pathogenic activity of the fungus, making it possible to create chemo libraries that facilitate the linking of the structure of the compounds with the species that produce it and its effect on host and non-host crops, as well as with biosynthetic features [12]. In this context, our work reports a study focused on NSTs and CWDEs used by an A. alternata strain isolated from infected pears in Italy. To this aim, the characterization of hydrolytic enzyme activities of A. alternata and the identification of the metabolites produced in vitro were performed. Furthermore, the phytotoxic activity of the isolated compounds was evaluated on pear (host and non-host varieties) and lemon fruits [13]. Finally, the competition of A. alternata with other pathogens was evaluated to investigate the role of NSTs on co-infections.

Fungi kingdom comprises ubiquitous forms of life with 1.5 billion years, mostly phytopathogenic and commensal for humans and animals. However, in the presence of impaired conditions fungi may cause disease by intoxicating, infecting or sensitizing with allergy. Different genera may be implicated as etiological agents for humans and animals, with Alternaria, Aspergillus, dermatophytes like Microsporum and Trichophyton, and Malassezia as the commonly implicated. Alternaria and Malassezia stand as the most commonly associated to either allergy or infection, immediately followed by Aspergillus, while dermatophytes are usually associated to ring worm skin infection. Research in veterinary field is not much but necessary.

Brown leaf spot disease caused by Alternaria spp. is among the most common diseases in potato crops. Typical brown spot symptoms were observed in commercial potato-cultivated areas of northern Korea during June 2021–2022. In total, 77 isolates were collected, and based on sequence analysis of the internal transcribed spacer (ITS) region, the collected isolates were identified as Alternaria spp. (83.1%). Phylogenetic analysis revealed that a majority of these isolates clustered within a clade that included A. alternata. Additionally, the ITS region and rpb2 yielded the most informative sequences for the identification of A. alternata. Pathogenicity tests confirmed that the collected pathogens elicited identical symptoms in the field. In the pathogenicity test performed on seven commercial cultivars, the pathogens exhibited strong virulence in both wound and non-wound inoculations. Among the cultivars tested, Arirang-1ho, Arirang-2ho, and Golden Ball were resistant to the pathogens. Furthermore, when testing effective fungicides in vitro, mancozeb and difenoconazole were found to be effective agents for inhibiting mycelial growth. In summary, our findings suggest that A. alternata plays a critical role in leaf disease in potato crop regions and emphasise the necessity for continuous monitoring and management to protect against this disease in South Korea.

Study of fungal antibiotics in their competitive interactions with arthropods may lead to development novel biorational insecticides. Extracts of Alternaria tenuissima MFP253011 obtained by various methods showed a wide range of biological activity, including entomotoxic properties. Analysis of their composition and bioactivity allowed to reveal several known mycotoxins and unidentified compounds that may be involved in entomotoxic activity of the extracts. Among them, tenuazonic acid (TeA), which was the major component of the A. tenuissima extracts, was found the most likely to have larvicidal activity against Galleria mellonella. In the intrahaemocoel injection bioassay, TeA was toxic to G. mellonella and of Zophobas morio with LT50 6 and 2 days, respectively, at the level of 50 µg/larva. Administered orally, TeA inhibited growth of G. mellonella larvae and caused mortality of Acheta domesticus imagines (LT50 7 days) at a concentration of 250 µg/g of feed. TeA showed weak contact-intestinal activity against the two phytophages, Tetranychus urticae and Schizaphis graminum, causing the 12 and 40% of mortality at a concentration of 1 mg/mL. TeA was cytotoxic to Sf9 cell line (IC50 25 µg/mL). Thus, model insect G. mellonella and cell line Sf9 could be used for a further toxicological characterization of TeA.