Search Results (16)

Claviceps purpurea is a highly specialized biotrophic ascomycete that colonizes floral tissues of grasses, including economically important cereal crops, causing ergot disease and producing ergot alkaloids with significant agricultural, pharmaceutical, and biotechnological relevance. Despite extensive research on its biology and secondary metabolism, the molecular mechanisms underlying host recognition, floral specificity, establishment of biotrophy, and developmental differentiation remain incompletely understood. This review integrates current knowledge derived from genomic, transcriptomic, proteomic, metabolomic, and functional genetic studies to provide an overview of the molecular basis of the C. purpurea–host interaction. Particular emphasis is placed on recent advances in fungal development, host immune modulation, hormonal signalling, sclerotial differentiation, and ergot alkaloid biosynthesis. Current evidence indicates that successful colonization depends on coordinated regulation of host recognition, secretion of effector proteins, carbohydrate-active enzymes, and manipulation of host signalling pathways to establish and maintain a biotrophic lifestyle. The transition from the sphacelial stage to sclerotial development represents a major developmental and metabolic reprogramming event associated with fungal differentiation and activation of the ergot alkaloid biosynthetic pathway. Recent multi-omics approaches have further revealed complex regulatory networks connecting fungal development and secondary metabolism. Claviceps purpurea has emerged as a valuable model for studying floral biotrophy and fungal secondary metabolism; however, key questions remain regarding the molecular basis of host specificity, effector function, hormonal crosstalk, and developmental regulation. Future integration of multi-omics approaches with functional genomics will be essential to resolve these processes and to support sustainable disease management strategies and the biotechnological exploitation of ergot alkaloids. Full article

We tested whether ergot alkaloids would affect the interaction of a protist with an ergot alkaloid-producing fungus by studying the response of the plasmodial slime mold Physarum polycephalum to cultures of Aspergillus leporis. Ergot alkaloid profiles were manipulated by culturing A. leporis and its easD knockout derivative on media for 6 or 13 days. Six-day-old, wild-type A. leporis samples contained abundant lysergic acid α-hydroxyethylamide (LAH) that was greatly depleted by 13 days. The intermediate chanoclavine-I was the predominant ergot alkaloid in all samples of the easD knockout. Inoculum of P. polycephalum was placed equidistant between the fungus-colonized agar medium explant, and the preference of the slime mold for either fungal explant was observed. When offered 6-day-old samples of wild-type A. leporis (containing mainly LAH) or the easD knockout (containing mainly chanoclavine-I), plasmodia of P. polycephalum preferred the easD knockout strain over wild type by a significant margin (p = 0.0002). When given the same options at 13 days, there was no longer a preference for the easD knockout over wild type, which by that time had lost more than 90% of its LAH. Our data demonstrate that ergot alkaloids, including LAH and chanoclavine-I, affect the interaction of P. polycephalum with A. leporis. Full article

Ergot alkaloids derived from lysergic acid have impacted humankind significantly as toxins in agriculture and as the foundations of several pharmaceuticals. Few fungi capable of producing lysergic acid derivatives have been found outside the family Clavicipitaceae. Based on its phylogenetic placement, we hypothesized the recently described fungus Aspergillus aspearensis (Aspergillaceae) would synthesize lysergic acid amides. Cultures of A. aspearensis produced abundant lysergic acid α-hydroxyethylamide (LAH) and lesser amounts of other lysergic acid derivatives. Conidia contained high concentrations of ergot alkaloids, whereas sclerotia contained significantly less. Approximately half of the ergot alkaloids produced were secreted into the culture medium. When spores of A. aspearensis were injected into larvae of the model insect Galleria mellonella, larvae died at a significantly faster rate than control larvae. The fungus produced ergot alkaloids during insect pathogenesis and later produced conidia and sclerotia on cadavers, indicating it can complete its life cycle in an insect. The genome of A. aspearensis contained two complete ergot alkaloid synthesis gene clusters, similar to those of A. leporis; however, unlike its sister species, none of the ergot cluster genes were pseudogenized. Aspergillus aspearensis is a newly discovered source of ergot alkaloids and may be useful for studying and producing these important chemicals. Full article

Reactive oxygen species (ROS) induce oxidative stress in cells and are associated with various diseases, including autoimmune diseases. Ergothioneine (EGT) is a natural amino acid derivative derived from the ergot fungus and has been reported to exhibit an effective antioxidant function in many models of oxidative stress-related diseases. Recently, mutations in OCTN1, a membrane transporter of EGT, have been reported to be associated with rheumatoid arthritis. Therefore, we investigated the chondrocyte-protective function of EGT using a model of oxidative stress-induced injury of chondrocytes by hydrogen peroxide (H₂O₂). Human chondrocytes were subjected to oxidative stress induced by H₂O₂ treatment, and cell viability, the activity of lactate dehydrogenase (LDH) released into the medium, dead cell ratio, intracellular ROS production, and mitochondrial morphology were assessed. EGT improved chondrocyte viability and LDH activity in the medium and strongly suppressed the dead cell ratio. EGT also exerted protective effects on intracellular ROS production and mitochondrial morphology. These results provide evidence to support the protective effects of EGT on chondrocytes induced by oxidative stress. Full article

Tall fescue (Lolium arundinaceum) is a highly adaptable forage, pasture and turf grass that is grown on over 14 M ha in the eastern half of the United States and in other temperate regions of the world. A significant factor in adaptability, productivity and stand persistence is in part due to the presence of an intercellular, seed-transmissible, endophytic fungus, Epichloë coenophiala. Epichloë endophytes have been shown to produce a number of alkaloid compounds only in planta, some that are beneficial in repelling insects, while others are toxic to animals. The goal of this work was to monitor the level of the ergot and loline (classified as pyrrolizidine) alkaloid accumulation in individual plants to determine the plant genotype contribution to alkaloid concentrations. The experimental design consisted of sixteen tall fescue KY31 clones in a space-planted, replicated trial over three years. Our results demonstrated that while changes in the alkaloid concentrations for each plant/endophyte genotype were observed over the three years, the overall alkaloid levels remained relatively constant when compared to other plant/endophyte genotypes combinations in the field. Additionally, overall levels of the ergot and loline alkaloid accumulation did not vary in the same way over the three years. Since the E. coenophiala endophyte genotype was the same across all clones, our results indicate that it is the plant genotype that is responsible for determining alkaloid levels in each plant, and suggest that the signal(s) from the plant to the endophyte may not be the same for ergot and loline alkaloid production. Full article

Ergot is the spore form of the fungus Claviceps purpurea. Ergot alkaloids are indole compounds that are biosynthetically derived from L-tryptophan and represent the largest group of fungal nitrogen metabolites found in nature. The common part of ergot alkaloids is lysergic acid. This review shows the importance of lysergic acid as a representative of ergot alkaloids. The subject of ergot and its alkaloids is presented, with a particular focus on lysergic acid. All methods of total lysergic acid synthesis—through Woodward, Hendrickson, and Szantay intermediates and Heck coupling methods—are presented. The topic of biosynthesis is also discussed. Full article

Periglandula is a fungal genus that is associated with plants in the family Convolvulaceae. They produce medicinally important constituents called ergot alkaloids, which are stored in their host plants. Previously, the fungi were reported to mainly interact with young leaves and seeds of Convolvulaceae species. However, knowledge about how ergot alkaloid-producing fungi interact with their host plants is still lacking. Therefore, we investigated the interaction of Periglandula fungus with different plant parts of Ipomoea asarifolia, using molecular, histochemical, anatomical and micromorphological techniques. Our findings confirm the presence of Periglandula ipomoeae on six out of the eight plant parts examined (young folded leaves, mature leaves, flower buds, mature flowers, young seeds and mature seeds). The fungus was mostly distributed along external plant surfaces, and particularly on areas that were relatively unexposed. Our results suggest that the density of fungal mycelium varies depending on glandular trichome density and the growth stage of the host plant. Detection of the fungus in the flowers of its host plant, for the first time, fills a missing link in understanding how vertical transmission of Periglandula species occurs. Full article

Ergot alkaloids (EAs) are mycotoxins mainly produced by the fungus Claviceps purpurea. EAs are known to affect the nervous system and to be vasoconstrictors in humans and animals. This work presents recent advances in swine and dairy feeds regarding 11 major EAs, namely ergometrine, ergosine, ergotamine, ergocornine, ergocryptine, ergocristine, ergosinine, ergotaminine, ergocorninine, ergocryptinine, and ergocristinine. A reliable, sensitive, and accurate multiple mycotoxin method, based on extraction with a Mycosep 150 multifunctional column prior to analysis using UHPLC-MS/MS, was validated using samples of swine feed (100) and dairy feed (100) for the 11 targeted EAs. Based on the obtained validation results, this method showed good performance recovery and inter-day and intra-day precision that are in accordance with standard criteria to ensure reliable occurrence data on EA contaminants. More than 49% of the swine feed samples were contaminated with EAs, especially ergocryptine(-ine) (40%) and ergosine (-ine) and ergotamine (-ine) (37%). However, many of the 11 EAs were not detectable in any swine feed samples. In addition, there were contaminated (positive) dairy feed samples, especially for ergocryptine (-ine) (50%), ergosine (-ine) (48%), ergotamine (-ine), and ergocristine (-ine) (49%). The mycotoxin levels in the feed samples in this study almost complied with the European Union regulations. Full article

Contamination by ergot caused by the phytopathogenic fungus Claviceps purpurea is a constant threat to the whole rye value chain. Ergot alkaloids (EA) produced within the fungal sclerotia are toxic for humans and animals and are subjected to strict regulations in human food. Our main objective was to analyze whether less susceptible rye cultivars with a lower content of sclerotia also contain fewer ergot alkaloids (EA). We analyzed 15 factorial single crosses in multi-environmental trials with artificial inoculation for their ergot severity, the content of twelve EAs by HPLC, and the total ergot content by ELISA. The genotypes displayed a wide range of pollen shedding from fully sterile to fully fertile, of ergot severity expressed as percentage of sclerotia relative to the harvest (0.22–11.47%), and of EA contents when analyzed by HPLC (0.57–45.27 mg/kg. Entry-mean heritabilities were high throughout (0.87–0.98). The factorial analysis yielded a preponderance of male general combining ability (GCA) variances, the estimates for the females were smaller, although significant. EA contents measured by ELISA were, on average, seven times larger. The correlation between ergot severity and EA contents determined by HPLC was r = 0.98 (p ≤ 0.01) and only somewhat lower when analyzed by ELISA. In conclusion, less ergot prone rye genotypes also support lower EA contents. Full article

Epichloë endophytes are filamentous fungi (family Clavicipitaceae) that live in symbiotic associations with grasses in the sub family Poöideae. In New Zealand, E. festucae var. lolii confers significant resistance to perennial ryegrass (Lolium perenne) against insect and animal herbivory and is an essential component of pastoral agriculture, where ryegrass is a major forage species. The fungus produces in planta a range of bioactive secondary metabolites, including ergovaline, which has demonstrated bioactivity against the important pasture pest black beetle, but can also cause mammalian toxicosis. We genetically modified E. festucae var. lolii strain AR5 to eliminate key enzymatic steps in the ergovaline pathway to determine if intermediate ergot alkaloid compounds can still provide insecticidal benefits in the absence of the toxic end product ergovaline. Four genes (dmaW, easG, cloA, and lpsB) spanning the pathway were deleted and each deletion mutant was inoculated into five different plant genotypes of perennial ryegrass, which were later harvested for a full chemical analysis of the ergot alkaloid compounds produced. These associations were also used in a black beetle feeding deterrence study. Deterrence was seen with just chanoclavine present, but was cumulative as more intermediate compounds in the pathway were made available. Ergovaline was not detected in any of the deletion associations, indicating that bioactivity towards black beetle can be obtained in the absence of this mammalian toxin. Full article

The grass parasitic fungus Claviceps purpurea sensu lato produces sclerotia with toxic indole alkaloids. It constitutes several genetic groups with divergent habitat preferences that recently were delimited into separate proposed species. We aimed to 1) analyze genetic variation of C. purpurea sensu lato in Norway, 2) characterize the associated indole alkaloid profiles, and 3) explore relationships between genetics, alkaloid chemistry and ecology. Approximately 600 sclerotia from 14 different grass species were subjected to various analyses including DNA sequencing and HPLC-MS. Molecular results, supported by chemical and ecological data, revealed one new genetic group (G4) in addition to two of the three known; G1 (C. purpurea sensu stricto) and G2 (C. humidiphila). G3 (C. spartinae) was not found. G4, which was apparently con-specific with the recently described C. arundinis sp. nov, was predominantly found in very wet habitats on Molinia caerulea and infrequently in saline habitats on Leymus arenarius. Its indole-diterpene profile resembled G2, while its ergot alkaloid profile differed from G2 in high amounts of ergosedmam. In contrast to G1, indole-diterpenes were consistently present in G2 and G4. Our study supports and complements the newly proposed species delimitation of the C. purpurea complex, but challenges some species characteristics including host spectrum, habitat preferences and sclerotial floating ability. Full article

Clavicipitaceous fungi producing ergot alkaloids were recently discovered to be epibiotically associated with peltate glandular trichomes of Ipomoea asarifolia and Turbina corymbosa, dicotyledonous plants of the family Convolvulaceae. Mediators of the close association between fungi and trichomes may be sesquiterpenes, main components in the volatile oil of different convolvulaceous plants. Molecular biological studies and microscopic investigations led to the observation that the trichomes do not only secrete sesquiterpenes and palmitic acid but also seem to absorb ergot alkaloids from the epibiotic fungal species of the genus Periglandula. Thus, the trichomes are likely to have a dual and key function in a metabolic dialogue between fungus and host plant. Full article

Ergot is a disease of cereals and grasses caused by fungi in the genus Claviceps. Of particular concern are Claviceps purpurea in temperate regions, C. africana in sorghum (worldwide), and C. fusiformis in pearl millet (Africa, Asia). The fungi infect young, usually unfertilized ovaries, replacing the seeds by dark mycelial masses known as sclerotia. The percentage of sclerotia in marketable grain is strictly regulated in many countries. In winter rye, ergot has been known in Europe since the early Middle Ages. The alkaloids produced by the fungus severely affect the health of humans and warm-blooded animals. In sorghum and pearl millet, ergot became a problem when growers adopted hybrid technology, which increased host susceptibility. Plant traits reducing ergot infection include immediate pollination of receptive stigmas, closed flowering (cleistogamy), and physiological resistance. Genetic, nonpollen-mediated variation in ergot susceptibility could be demonstrated in all three affected cereals. Fungicides have limited efficacy and application is weather dependent. Sorting out the sclerotia from the harvest by photocells is expensive and time consuming. In conclusion, molecular-based hybrid rye breeding could improve pollen fertility by introgressing effective restorer genes thus bringing down the ergot infection level to that of conventional population cultivars. A further reduction might be feasible in the future by selecting more resistant germplasm. Full article

Several fungi in two different families––the Clavicipitaceae and the Trichocomaceae––produce different profiles of ergot alkaloids, many of which are important in agriculture and medicine. All ergot alkaloid producers share early steps before their pathways diverge to produce different end products. EasA, an oxidoreductase of the old yellow enzyme class, has alternate activities in different fungi resulting in branching of the pathway. Enzymes beyond the branch point differ among lineages. In the Clavicipitaceae, diversity is generated by the presence or absence and activities of lysergyl peptide synthetases, which interact to make lysergic acid amides and ergopeptines. The range of ergopeptines in a fungus may be controlled by the presence of multiple peptide synthetases as well as by the specificity of individual peptide synthetase domains. In the Trichocomaceae, diversity is generated by the presence or absence of the prenyl transferase encoded by easL (also called fgaPT1). Moreover, relaxed specificity of EasL appears to contribute to ergot alkaloid diversification. The profile of ergot alkaloids observed within a fungus also is affected by a delayed flux of intermediates through the pathway, which results in an accumulation of intermediates or early pathway byproducts to concentrations comparable to that of the pathway end product. Full article

Ergot alkaloids are pharmaceutically and agriculturally important secondary metabolites produced by several species of fungi. Ergot alkaloid pathways vary among different fungal lineages, but the pathway intermediate chanoclavine-I is evolutionarily conserved among ergot alkaloid producers. At least four genes, dmaW, easF, easE, and easC, are necessary for pathway steps prior to chanoclavine-I; however, the sufficiency of these genes for chanoclavine-I synthesis has not been established. A fragment of genomic DNA containing dmaW, easF, easE, and easC was amplified from the human-pathogenic, ergot alkaloid-producing fungus Aspergillus fumigatus and transformed into Aspergillus nidulans, a model fungus that does not contain any of the ergot alkaloid synthesis genes. HPLC and LC-MS analyses demonstrated that transformed A. nidulans strains produced chanoclavine-I and an earlier pathway intermediate. Aspergillus nidulans transformants containing dmaW, easF, and either easE or easC did not produce chanoclavine-I but did produce an early pathway intermediate and, in the case of the easC transformant, an additional ergot alkaloid-like compound. We conclude that dmaW, easF, easE, and easC are sufficient for the synthesis of chanoclavine-I in A. nidulans and expressing ergot alkaloid pathway genes in A. nidulans provides a novel approach to understanding the early steps in ergot alkaloid synthesis. Full article