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Examples of the four major classes of endophyte alkaloids. Lolitrem B, peramine, N-acetyl loline, and ergotamine represent indolediterpenoid, pyrrolopyrazine, aminopyrrolizidine and ergot alkaloids, respectively. Individual infected grasses may have various mixtures of alkaloids.
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Over the past 20 yr much has been learned about a unique symbiotic interaction between fungal endophytes and grasses. The fungi (Clavicipitaceae, Ascomycota) grow intercellularly and systemically in aboveground plant parts. Vertically transmitted asexual endophytes forming asymptomatic infections of cool-season grasses have been repeatedly derived...
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Context 1
... seed-transmitted endophytes produce alkaloids that likely play some role in benefiting the host plant against pests (table 2). Several distinct classes of alkaloids are known from clavicipitaceous endophytes including ergot alkaloids similar to those from Claviceps (Groger 1972). Other classes include saturated aminopyrrolizidine (loline) alkaloids, indolediterpenoid (lolitrem) alkaloids and pyr- rolopyrazine (peramine) alkaloids. Examples of chemical structures are shown in figure 5. Siegel et al. (1990) found that peramine was present in the majority of endophyte- infected host grasses followed by ergot alkaloids (50%), loline alkaloids (35%), and lolitrems (10%). Some of these alkaloids are known only from Epichloë and Neotyphodium species but ergot alkaloids are widespread in the plant parasitic Clavicipitaceae. A number of detailed reviews of endophyte alkaloids have been published (Porter 1994;Bush et al. 1997;Siegel and Bush ...
Context 2
... alkaloid toxicity (ergotism) has been known for many centuries (Groger 1972) and several ergot alkaloids have pharmaceutical applications. Many ergot alkaloids are derived from variations on the basic ergoline ring structure (see Siegel and Bush 1997; fig. 5). Ergot alkaloids have been detected in a wide variety of endophyte-infected grass species, but specific chemical composition and concentra- tions vary with the symbiotic combination. For example, in tall fescue infected with Neotyphodium coenophialum the predominant ergot alkaloid is ergovaline ( Arechavaleta et al. 1992), whereas in sleepygrass (Achnatherum robustum p Stipa robusta) and Achnatherum inebrians infected by other Neotyphodium species, the predominant ergot al- kaloids are lysergic acid amide ( Petroski et al. 1992) and ergonovine ( Miles et al. 1996), respectively. Ergobalansine is the major alkaloid component produced by Balansia cyperi, which infects a variety of tropical and subtropical sedges, and Balansia obtecta, which infects sandbur grass, Cenchrus echinatus ( Powell et al. ...
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Citations
... Loline alkaloids also occur in the root system, which suggests that they are transferred from the leaf sheath and stem, which are thought to be synthesis sites, and translocated through the phloem and possibly upwards in the xylem [55]. Endophytic fungal hyphae in plants follow a gradient with high concentrations in the basal regions to low concentrations at the apical parts, and colonise grasses exclusively above ground [1,7,56]. The association's highly compatible nature is responsible for this carefully controlled growth. ...
... Secondary metabolites produced as a result of grass-endophyte interactions can have both direct and indirect effects to plant parasitic nematodes. Directly, they can interact with the nematodes' motile stages causing paralysis (nematostatic) or death (nematicidal) [56]. Direct interaction of the secondary metabolites with soil-inhabiting plant parasitic nematodes involves the translocation of the compounds to the root systems and subsequent exudation, which then has a negative effect on the development and reproduction of the nematode [59]. ...
Claviceptaceous endophytic fungi in the genus Epichloë mostly form a symbiotic relationship with cool-season grasses. Epichloë spp. are capable of producing bioactive alkaloids such as peramines, lolines, ergot alkaloids, and indole-diterpenes, which protect the host plant from herbivory by animals, insects, and nematodes. The host also benefits from enhanced tolerance to abiotic stresses, such as salt, drought, waterlogging, cold, heavy metals, and low nitrogen stress. The bioactive alkaloids produced can have both direct and indirect effects towards plant parasitic nematodes. Direct interaction with nematodes’ motile stages can cause paralysis (nematostatic effect) or death (nematicidal effect). Indirectly, the metabolites may induce host immunity which inhibits feeding and subsequent nematode development. This review highlights the different mechanisms through which this interaction and the metabolites produced have been explored in the suppression of plant parasitic nematodes and also how the specific interactions between different grass genotypes and endophyte strains result in variable suppression of different nematode species. An understanding of the different grass–endophyte interactions and their successes and failures in suppressing various nematode species is essential to enable the proper selection of grass–endophyte combinations to identify the alkaloids produced, concentrations required, and determine which nematodes are sensitive to which specific alkaloids.
... isolates 32 , altersolanols, alterporriols and anthracene derivatives from S. globuliferum isolated from Mentha pulegium22,23,32 . Most of these natural products have promising biological and pharmacological activities, such as cytotoxic and antimicrobial[18][19][20]22,23,[33][34][35][36] , including stempholone B(2) ...
The continuous search for natural product-based biopesticides from fungi isolated from untapped sources is an effective tool. In this study, we studied a pre-selected fungal endophyte, isolate Aa22, from the medicinal plant Artemisia absinthium, along with the antifungal, insect antifeedant and nematicidal compounds present in the extract. The endophyte Aa22 was identified as Stemphylium solani by molecular analysis. The antifungal activity was tested by broth microdilution against Fusarium solani, F. oxysporum, F. moniliforme and Botrytis cinerea, the insect antifeedant by choice bioassays against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi and the in vitro mortality against the root-knot nematode Meloiydogyne javanica. The structures of bioactive compounds were determined on the basis of 1D and 2D NMR spectroscopy and mass spectrometry. The ethyl acetate extract obtained from the solid rice fermentation showed mycelial growth inhibition of fungal pathogens (EC50 0.08–0.31 mg/mL), was antifeedant to M. persicae (99%) and nematicidal (68% mortality). A bioguided fractionation led to the isolation of the new compound stempholone A (1), and the known stempholone B (2) and stemphol (3). These compounds exhibited antifeedant (EC50 0.50 mg/mL), antifungal (EC50 0.02–0.43 mg/L) and nematicidal (MLD 0.5 mg/mL) activities. The extract activities can be explained by 3 (antifungal), 1–3 (antifeedant) and 1 (nematicidal). Phytotoxicity tests on Lolium perenne and Lactuca sativa showed that the extract and 1 increased L. sativa root growth (121–130%) and 1 reduced L. perenne growth (48–49%). These results highlight the potential of the endophytic fungi Aa22 as biotechnological source of natural product-based biopesticides.
... Comparatively, toxins produced by fungal endosymbionts are currently limited to just three plant families-Convolvulaceae, Fabaceae, and Poaceae (Quach et al. 2023). While considerable research has been conducted, largely in grasses, to investigate endosymbiont toxins (reviewed Rudgers and Clay 2007, Clay and Schardl 2002, Schardl et al. 2006, this area of inquiry is still quite understudied and additional fungal derived secondary defensive compounds are likely to be found. Previous surveys on the geographic distribution of endophytic toxins are limited to Poaceae, very few of which have investigated toxin distributions at local scales. ...
... Optimal Defense Theory, Resource Availability Hypothesis; Coley 1987;Stamp 2003). Moreover, association with fungal endophytes is expected to come at a cost that is outweighed by the bene ts that plant receives from the interaction (Clay and Schardl 2002;Davitt et al. 2010). There is ample evidence in other endophytic fungi-plant toxin systems that these associations provide protection from various vertebrate and insect herbivores (Omacini et al. 2001, Brem and Leuchtmann 2001, Siegel and Bush 1997, Clay et al. 2005. ...
Legumes are notorious for coevolutionary arms races where chemical defenses are employed to ward off herbivores—particularly insect seed predators. Locoweeds are a group of plants containing the toxic alkaloid swainsonine which can poison livestock and causes millions in economic damage every year. Swainsonine is known to be produced by the fungal endophyte Alternaria section Undifilum , and the chemical composition of the toxin has been well characterized. Despite this knowledge, the ecological roles and evolutionary drivers of swainsonine toxins in locoweeds remain uncertain. Here, we quantitate swainsonine concentrations and herbivory levels in the hyper-diverse locoweed Astragalus lentiginosus to evaluate its role as an evolved chemical defense. We found that A. lentiginosus shows considerable variation in swainsonine concentrations according to variety, in particular showing presence/absence variation at both population and local geographic scales. Surprisingly, herbivory levels from presumed generalist insects emerging from fruits showed no correlation with swainsonine concentrations. Conversely, seed and fruit herbivory levels linked to specialist Acanthoscelides seed beetles actually increased with concentrations of swainsonine—suggesting a possible coevolutionary arms race. Our results highlight that variation in endophyte-produced toxin systems may not follow classical expectations for geographic variation and ecological roles of plant chemicals. We discuss the implications of these results on plant-endophytic toxin systems and coevolutionary dynamics more broadly, highlighting a considerable need for more research in these systems.
... ). In these cases, grasses are infected systemically by endophytic fungi (Clavicipitaceae) that produce a variety of ergot alkaloid compounds deterrent or toxic to domestic mammals and increase resistance to insect herbivores (Clay 1988;Clay & Schardl 2002). Interestingly, the next plant generation inherits these symbiotic fungi through vertical transmission in the grass seeds (Schardl 2007). ...
Many Convolvulaceae species harbor heritable fungal endophytes from which alkaloids are translocated to reproductive tissues of the plant host. Evidence for the distribution and ecological role of these fungal alkaloids, however, is lacking or incomplete for many host species and growth forms. Here we report on the quantities of alkaloids present in the leaves and seeds of the arborescent morning glory, Ipomoea murucoides (Convolvulaceae). Young leaf samples taken from the wild harbored one of two fungal taxa. Seeds had higher concentrations of the indolizidine alkaloid swainsonine than leaves. Additionally, seeds from trees harboring Ceramothyrium (Chaetothyriales) fungi exhibited less bruchid damage and had higher concentrations of swainsonine than seeds from trees harboring Truncatella (Xylariales) fungi. Five sesquiterpenes were detected in the leaf trichomes of both types of trees. The seed content of the nortropane alkaloids, tropine and tropinone, did not differ significantly among the two fungal symbionts. Overall, our field data support the defensive-symbiosis hypothesis for swainsonine as proposed by Clay (2014) where the fungal partner supplies chemical defenses to the host. It is likely that the host allocates the defensive chemicals from leaves to seeds, protecting them from seed predators such as bruchid beetles.
... Endophytic fungi, which develop intercellularly within aboveground tissues, have the ability to enhance the viability of the host grass by bolstering its tolerance to both biotic and abiotic stresses. Furthermore, endophytes have the ability to promote growth through the enhancement of photosynthetic rate (Clay and Schardl 2002) and nitrogen uptake (Christian et al. 2019, Bayat et al. 2023. ...
... This is an important perennial temperate grass species with a great diversity of morphotypes (Continental and Mediterranean) and cultivars product of breeding programmes (Hand et al., 2010;Milne, 2009). This species is usually infected by the asexual endophyte Epichloë coenophiala (Morgan-Jones & W. Gams) C.W. Bacon & Schard (Leuchtmann et al., 2014) that is only transmitted through the seed (i.e., vertical transmission; Clay & Schardl, 2002). From an agronomical perspective, this association exhibits both desirable and undesirable characteristics. ...
Tall fescue (Festuca arundinacea Schreb.) is a perennial C3 grass species usually associated with the endophyte fungus Epichloë coenophiala that enhances tolerance to biotic and abiotic stresses. Given that the proportion of infected tall fescue plants in the grasslands of the Flooding Pampa (Argentina) has been progressively increasing, it is proposed that endophytes confer tolerance to the stresses characteristic of that environment, especially flooding. Plants from a naturalized population and a commercial cultivar were grown, both with and without endophyte (wild type and AR584 respectively). The plants were subjected to two submergence treatments (i.e., control and partial submergence) in two development stages (5-leaf stage and beginning of the elongation of internodes). Plant performance (aerial and root biomass, root aerenchyma formation, total root length and root diameter, proportion of reproductive tillers, number of panicles and seeds produced) and endophyte transmission to progeny were evaluated. Endophytes did not alter the ecological fitness of plants under partial submergence. Independently of the water condition, the symbiosis was linked to low biomass in plants from the naturalized population, while the opposite occurred in plants from the cultivar. Partial submergence did not affect the germination of the seeds produced, nor the transmission of the endophyte to the seedlings that originated from them. Our work suggests that the invasion ability of tall fescue in the Flooding Pampa grasslands is not related to an endophyte-mediated improvement of plants to tolerate water excess.
... The endophytic fungi Epichloë, studied in this research, typically forms mutualistic symbiotic associations predominantly with cool-season grasses [8]. The host grass provides nutrients to Epichloë, which in turn enhances the host's resistance to biotic and abiotic stresses such as drought, herbivory, and pathogen infections [9][10][11]. ...
In nature, the symbiotic relationship between plants and microorganisms is crucial for ecosystem balance and plant growth. This study investigates the impact of Epichloë endophytic fungi, which are exclusively present aboveground, on the rhizosphere microbial functions of the host Melica transsilvanica. Using metagenomic methods, we analyzed the differences in microbial functional groups and functional genes in the rhizosphere soil between symbiotic (EI) and non-symbiotic (EF) plants. The results reveal that the presence of Epichloë altered the community structure of carbon and nitrogen cycling-related microbial populations in the host’s rhizosphere, significantly increasing the abundance of the genes (porA, porG, IDH1) involved in the rTCA cycle of the carbon fixation pathway, as well as the abundance of nxrAB genes related to nitrification in the nitrogen-cycling pathway. Furthermore, the presence of Epichloë reduces the enrichment of virulence factors in the host rhizosphere microbiome, while significantly increasing the accumulation of resistance genes against heavy metals such as Zn, Sb, and Pb. This study provides new insights into the interactions among endophytic fungi, host plants, and rhizosphere microorganisms, and offers potential applications for utilizing endophytic fungi resources to improve plant growth and soil health.
... These plants are ralatively resistance to diseases, so it was assumed that there is some endophytic fungi live in the plant tissues and have a mutualism symbiotic interaction with these plants. Some previous researches proved that several endophytic fungi species have a mutualism symbiotic interaction with the host plant and the host plant relatively resistant towards some pathogenic microorganisms [1,2]. Some endophytic fungi species isolated from a medicinal plant, Hedycium acuminatum, potencially produce some antimicrobial compounds that can inhibite the growth of pathogenic bacteria that attacked host plant [3]. ...
... The precious research have been reported that some species of endophytic fungi that lived in Cananga odorata leaf, branch bark and flower petal tissues have a mutuliasm symbiotic interaction with the endophytic fungi, i.e: Colletotrichum alienum, C. kahawae, C. aotearoa, C. alatae, C. queenslandicum, Nigrospora sphaerica, Mycelia sterile 1 and Mycelia sterile 2. The endophytic fungi could protect the host plant from bacteria infection by produce some antimicrobial secondary metabolites. Besides that, the endophytic fungi also get some advantages from the host plant, i.e: protection from environmental stress such as low humadity, high air temperature, drought, and also nutrition [1,2]. The endophytic fungi live on the epidermis cell wall and parenchyma cell wall of Switenia mahagoni twigs, on the epidermis, vascular tissues and stoma guard cell wall of this plant leaves. ...
Cosmos caudatus and Cosmos sulphureus are sorts of plant commonly use for side dish vegetables. Some plant live in mutualism symbiotic interaction with some endophytic fungi that protect the host plant. This research is done to: 1) determine the endophytic fungi colonization in the Cosmos plant tissues by histologic observation, 2) isolation and identify the endophytic fungi species from Cosmos leaf, branch bark and flower petal tissues, 3) analyze alkaloid, flavonoid, tannin, saponin, and phenolic contents produced by the each endophytic fungi species. The endophytic fungi culture on PDA medium were cut into 5×1 cm in size and inoculated in PDB medium, then shake in the rate of 120 rpm for 7×24 hours. Afterwards the liquid centrifugated. The secondary metabolites contents were analyzed by using spectrophotometric method. This research result showed that: 1) the endophytic fungi position was found on the leaf palisade cell wall, epidermal cell wall, sponsa cell wall, neighbour cell wall; on the branch bark parenchyme cell wall; on the flower petal epidermis cell wall; 2) eleven endophytic fungi have been identified; 3) some variation in the secondary metabolites contents produced by each endophytic fungi.
... The endophyte N. coenophialum either E WT or E AR542 forms a unique mutualistic/symbiotic relationship with the host grass, F. arundinacea, causing an increase in the yield (Clay and Schardl 2002;Schulz et al. 1999). This increase in the yield is attributed to the increased resistance of the grass to number of abiotic and biotic stress including insects feeding on the host grass (Hewitt et al. 2021; Katrin et al. 2021;; Popay et al. 2009). ...
... Acremonium strictum E WT infection and α-terpinene, representing < 1% of the total volatiles produced, which levels has not signi cantly affected (Jallow et al. 2008 is likely to be a part of the mutualism established between F. arundinacea and N. coenophialum, where the fungi alters the pro les of volatile compounds and the production of some secondary compounds to achieve optimal metabolic changes as suggested by Clay & Schardl (2002) and Schulz et al. (1999). ...
Mediterranean (M) and Continental (C) Festuca arundinacea cultivars in Australia are either endophyte–free (E–) or uniquely infected with the fungal endophyte Neotyphodium coenophialum strain AR⁵⁴² (EAR542). The impact of volatile oils produced by Mediterranean and Continental cultivars in response to EAR542 on enhancing the grass’s resistance to insects is still largely unknown. In this study, we determined the volatile-oil profiles produced by ME–, CE–, MEAR542 and CEAR542 cultivars and their impacts on the host-selection behavior of H. arator adults.
A total of 22 volatile compounds were detected in all F. arundinacea samples tested irrespective of being from Mediterranean or Continental cultivars and with or without endophyte. Octanal, 2-ethylhexanol, dodecane, (Z)-2-hexen1-1-ol, butyl hexanoate, (Z)-3-hexen-1-ol, 1-octen-3-ol, and butylated hydroxytoluene were the major compounds identified and variably influenced by the germplasm and endophyte infection status. Quantitatively, ME– expressed lesser quantities of 1,6-octandien-1-ol, hexanal, hexanol, 1-octen-3-ol and ethyl-3-hydroxypentanoate compared with CE– but greater quantities of butylated hydroxytoluene and hexylhexanoate. Compared with ME–, the quantities of octanal, 2-ethylhexanol, pentanal, hexanal, undecanal, 1-octen-3-ol, (Z)-2-octen-1-ol and clovene were greater in MEAR542. However, compared with CE–, hexanal, undecanal, undecane, i-octen-3-ol, (Z)-2-octen-1-ol, cloven and butylated hydroxytoluene were greater in CEAR542. In four-choice assay, the percentage of the numbers of H arator adult males choosing one of the choices ME–, MEAR542, CE– or CEAR542 was not significantly different compared to females choosing any of the respective choices. The impact of the germplasm on the host selection of H. arator adults was determined using two-choice assay olfactometer. The H. arator adults significantly (χ² = 10 d.f. = 1, P < 0.002) preferred ME– compared with CE–. In contrast, the CEAR542 was significantly (χ² = 26.67, d.f. = 1, P < 0.05) preferred host by same beetles compared with MEAR542.
Mediterranean germplasm is different to the Continental germplasm in relation to the quantities of volatile compounds produced and these quantities in Mediterranean and Continental cultivars variably influenced by EAR542 infection. Whether changes in quantities of the volatile compounds in EAR542–infected grasses impose any agricultural or ecological impact require further investigation.
... It has been observed that solely plant-pathogen interaction is not able to produce secondary metabolites, as this relationship is one-sided as endophytes are also required for the production of metabolites (Ludwig-Müller 2015). Hence, plants benefit from their mutualistic endophytic partner in terms of secondary metabolite production which provides stress tolerance as well as defensive ability to the host (Clay and Schardl 2002;Strobel et al. 2004;Knop et al. 2007). Although endophytes produce a diverse group of compounds including phenols, terpenoids, and steroids, they sometimes constitute the derivatives of these compounds . ...
Recent decades have witnessed a significant progress in identifying novel and economically viable therapeutic compounds from natural resources. There is an increased interest in determining various plant-based compounds as an alternative to commercially available antibiotic drugs. However, endophytes, despite being a treasure house for a number of secondary metabolites, including antimicrobial compounds, are still less explored. These microbes are well known to produce hydrolytic enzymes, phenols, and terpenes which contribute to plants’ defense against pathogens as well as predators. Endophytes using similar biosynthetic pathways to their host sometimes mimic the production of secondary metabolites because of which they become equally efficient for drug development. This chapter explores the endophytes known for producing antimicrobial compounds and describes various biosynthetic pathways used by them for their production. In addition, we have discussed the role of endophyte-derived antimicrobial metabolites in both their host plant and their benefits to mankind in combating the problem of antimicrobial resistance.
