Endophytes Of Grasses Research Articles

Intraspecific competition of endophyte infected vs uninfected plants of two woodland grass species

Grass endophytes (Clavicipitaceae, Ascomycota) are generally considered to be mutualists which increase the host's fitness. Infected plants are often more persistent and competitive than uninfected plants, influencing population dynamics and plant community diversity. However, most of this empirical evidence is based on studies focusing on agronomically important grass species such as tall fescue or perennial ryegrass and their implications for livestock and man‐made habitats. Recent studies indicate that endophyte‐plant associations may be more variable, ranging from parasitic to mutualistic. In the present study, we investigated the influence of endophyte infection on two wild woodland grasses, which are naturally infected with distinct fungal endophytes: Brachypodium sylvaticum with Epichloë sylvatica and Bromus benekenii with Epichloë bromicola. An intraspecific competition experiment was conducted over two growing seasons in the greenhouse and in an experimental garden. At first harvest (after 12 weeks growing), endophyte infection had a significant negative effect on above ground dry matter yield (DMY) of B. sylvaticum, but a significant positive effect on DMY of Br. benekenii under competition. The same differential effects on DMY and on total seed number were also observed at final harvest (after 62 weeks growing). Results from Br. benekenii were consistent with our hypothesis of increased competitive abilities of infected plants in nature which could explain the high infection rate observed in natural populations. In contrast, this explanation does not hold true for B. sylvaticum, and other factors such as increased herbivore and pathogen resistance together with frequent horizontal transmission may be responsible for the very high incidence of this association in nature. Our results confirm previous predictions that beneficial effects of endophyte infection in wild grasses can vary for different grass species, even in comparable habitats.

Elimination of ergovaline from a grass-Neotyphodium endophyte symbiosis by genetic modification of the endophyte.

The fungal endophytes Neotyphodium lolii and Neotyphodium sp. Lp1 from perennial ryegrass (Lolium perenne), and related endophytes in other grasses, produce the ergopeptine toxin ergovaline, among other alkaloids, while also increasing plant fitness and resistance to biotic and abiotic stress. In the related fungus, Claviceps purpurea, the biosynthesis of ergopeptines requires the activities of two peptide synthetases, LPS1 and LPS2. A peptide synthetase gene hypothesized to be important for ergopeptine biosynthesis was identified in C. purpurea by its clustering with another ergot alkaloid biosynthetic gene, dmaW. Sequence analysis conducted independently of the research presented here indicates that this gene encodes LPS1 [Tudzynski, P., Holter, K., Correia, T., Arntz, C., Grammel, N. & Keller, U. (1999) Mol. Gen. Genet. 261, 133-141]. We have cloned a similar peptide synthetase gene from Neotyphodium lolii and inactivated it by gene knockout in Neotyphodium sp. Lp1. The resulting strain retained full compatibility with its perennial ryegrass host plant as assessed by immunoblotting of tillers and quantitative PCR. However, grass-endophyte associations containing the knockout strain did not produce detectable quantities of ergovaline as analyzed by HPLC with fluorescence detection. Disruption of this gene provides a means to manipulate the accumulation of ergovaline in endophyte-infected grasses for the purpose of determining the roles of ergovaline in endophyte-associated traits and, potentially, for ameliorating toxicoses in livestock.

Production of loline alkaloids by the grass endophyte, Neotyphodium uncinatum, in defined media

Lolines (saturated 1-aminopyrrolizidines with an oxygen bridge) are insecticidal alkaloids produced in symbioses of certain Epichloë (anamorph- Neotyphodium) species (fungal endophytes) with grasses, particularly of the genera Lolium and Festuca. Prior to the present study, it was unknown whether lolines were of plant or fungal origin. Neotyphodium uncinatum, the common endophyte of meadow fescue ( Lolium pratense=Festuca pratensis) produced loline, N-acetylnorloline, and N-formylloline when grown in the defined minimal media at pH 5.0–7.5, with both organic and inorganic nitrogen sources and sugars as carbon sources. In contrast, lolines were not detected in complex medium cultures. GC–MS and 13C NMR spectroscopic analyses confirmed the identity of the alkaloids isolated from the defined medium cultures. Lolines accumulated to ca. 700 mg/l (4 mM) in cultures with 16.7 mM sucrose and 15–30 mM asparagine, ornithine or urea. Kinetics of loline production and fungal growth were assessed in defined medium with 16.7 mM sucrose and 30 mM ornithine. The alkaloid production rate peaked after the onset of stationary phase, as is common for secondary metabolism in other microbes.

Symbiosis and the Regulation of Communities1

Ecologists have long been interested in factors that control the structure of communities and the relative importance of top-down effects of predators versus bottom-up effects of resources. There is a growing body of evidence that microbial symbioses are important determinants of plant community structure and indirectly affect herbivore and predator trophic levels. Studies with mycorrhizal fungi, N-fixing bacteria and endophytes of grasses have demonstrated that they can affect competition, coexistence, soil nutrient dynamics and plant-herbivore interactions. Long-term field experiments with one grass/endophyte interaction suggest that grassland community structure is determined by the fungus. While total plant productivity of experimental plots was similar, the composition of the vegetation was altered by endophyte symbiosis. The host grass tall fescue (Festuca arundinacea) dominated plots when infected while other grasses greatly increased in uninfected plots. Indirect evidence suggests that changes in prairie vole (Microtus ochrogaster) grazing patterns and reproductive physiology may be in part responsible for vegetational changes. These results provide evidence that, in addition to bottom-up and top-down forces, microbial symbionts of plants are important determinants of community structure.

Symbiosis and the Regulation of Communities

Ecologists have long been interested in factors that control the structure of communities and the relative importance of top-down effects of predators versus bottom-up effects of resources. There is a growing body of evidence that microbial symbioses are important determinants of plant community structure and indirectly affect herbivore and predator trophic levels. Studies with mycorrhizal fungi, N-fixing bacteria and endophytes of grasses have demonstrated that they can affect competition, coexistence, soil nutrient dynamics and plant-herbivore interactions. Long-term field experiments with one grass/endophyte interaction suggest that grassland community structure is determined by the fungus. While total plant productivity of experimental plots was similar, the composition of the vegetation was altered by endophyte symbiosis. The host grass tall fescue (Festuca arundinacea) dominated plots when infected while other grasses greatly increased in uninfected plots. Indirect evidence suggests that changes in prairie vole (Microtus ochrogaster) grazing patterns and reproductive physiology may be in part responsible for vegetational changes. These results provide evidence that, in addition to bottom-up and top-down forces, microbial symbionts of plants are important determinants of community structure.

Presence of Neotyphodium‐like endophytes in European grasses

SummaryIn order to improve knowledge of Neotyphodium‐likc fungi in European grasses, microscopic detection of endophytic mycelium was achieved in living grasses and in seeds. Samples of grasses were gathered near permanent pastures or along paths in France (93 samples, 13 genera, 22 species). Typical convoluted mycelium was found inside leaf sheaths of four genera, especially in Festuca and Lolium spp. The results suggest that endophytes were present most often in the southern regions where plants may suffer from summer drought. Endophytes were looked for in 489 seed samples (63 genera, 237 species) received from 24 European botanical gardens. Neotyphodium was found in seeds of only six genera (22 species), especially in Festuca (15 species) and Lolium (three species). No endophytic mycelium was found in the other 215 species, although other work had demonstrated the presence of the fungus in 39 of the species analysed. Neotyphodium‐likc mycelium was detected for the first time in Festuca juncifolia, F. trachyphylla, F. vaginata, F. pseudodalmatica, F. rupicaprina, F. arenaria, Vulpia ciliata and Micropyrum tenellum. Further studies are needed for the correct identification of the Neotyphodium species observed.

Incidence and Diversity of Neotyphodium Fungal Endophytes in Tall Fescue from Morocco, Tunisia, and Sardinia

There is a premium on having Neotyphodium germplasm available for temperate grass improvement programs because these fungal endophytes present opportunities for developing new grass–endophyte combinations for enhanced tolerance to abiotic and biotic stresses. Unfortunately, surveys have revealed a low incidence of Neotyphodium fungi in grass germplasm collections. This research surveyed tall fescue (Festuca arundinacea Schreb.) accessions from a 1994 Australian–U.S. plant‐collection trip to Morocco, Tunisia, and Italy (Sardinia) for viable Neotyphodium fungi and determined whether infected accessions harbor different Neotyphodium genotypes. Conidial measurements of isolates cultured on agar and bioassays of the differential survival of bird cherry‐oat aphid [Rhopalosiphum padi (L.)] on infected accessions were used to characterize Neotyphodium diversity. A secondary objective determined the consistency of a polymerase chain reaction (PCR) method to detect Neotyphodium fungi in tall fescue. Neotyphodium was detected in 336 of 439 plants (76.5%) distributed among 104 accessions, of which 99 were endophyte‐infected. Mean conidial lengths of 42 isolates ranged from 3.91 to 9.91 μm. Most of the isolates (71.4%) had conidia with mean lengths smaller than the lower limit (6.5 μm) characteristic of the tall fescue endophyte N. coenophialum (Morgan‐Jones and Gams) Glenn, Bacon, and Hanlin. In aphid assays, all endophyte‐free plants were susceptible to R. padi and all but two infected plants were resistant to this aphid. Thus, a Mediterranean plant‐collection trip secured diverse Neotyphodium endophytes in tall fescue for storage in seed banks, and a PCR assay detected Neotyphodium in tall fescue plants of diverse geographical origin.

Leifsonia xyli-like bacteria are endophytes of grasses in eastern Australia

Bacteria serologically related to Leifsonia xyli ssp. xyli, the causal bacterium of ratoon stunting disease (RSD) in sugarcane, were detected using the fluorescent antibody direct count on filter (FADCF) technique in grasses in eastern Australia. In a survey of 191 grass, sedge and bullrush samples comprising 53 plant species, 90 (47%) of the samples tested harboured bacteria which reacted positively with L. xyli ssp. xyli polyclonal antiserum. A total of 18 grass species was found to be naturally colonised with bacteria serologically related to and morphologically similar to L. xyli ssp. xyli. Grasses colonised by these L. xyli-like bacteria were present in areas both adjacent to, and removed from, sugarcane crops. When L. xyli-like bacteria from Rhodes grass (Chloris gayana) were inoculated into sugarcane, they multiplied at a lower rate than L. xyli ssp. xyli. L. xyli-like bacteria in Rhodes grass were isolated in axenic culture and exhibited growth rates, colony size and pigmentation similar to those of L. xyli ssp. cynodontis, a bacterial pathogen of Cynodon dactylon (couch grass). Further, using a polymerase chain reaction (PCR) test that could differentiate L. xyli spp. xyli from L. xyli spp. cynodontis, the L. xyli-like bacteria infecting Rhodes grass, couch grass and panic grass (Panicum maximum) generated a product of the same size as L. xyli spp. cynodontis. We conclude that L. xyli ssp. cynodontis or closely related bacteria are common endophytes of grasses in eastern Australia.

Advancing dairy farming profitability through research

The New Zealand dairy industry recognises that to remain competitive it must continue to invest in research and development. Outcomes from research have ensured year-round provision of low-cost feed from pasture while improving productivity. Some of these advances, discussed in this paper, include the use of white clover in pasture, understanding the impacts of grass endophyte, improved dairy cow nutrition, the use of alternative forage species and nitrogen fertiliser to improve productivity, demonstration of the impact of days-in-milk on profitability, and the use of feed budgeting and appropriate pasture management. Keywords: dairy, profitability, research and development

Neotyphodium endophytes in grasses: deterrents or promoters of herbivory by leaf-cutting ants?

Endophytic fungi, particularly in the genus Neotyphodium, are thought to interact mutualistically with host grasses primarily by deterring herbivores and pathogens via production of alkaloidal mycotoxins. Little is known, however, about how these endophytes interact with host plants and herbivores outside the realm of agronomic forage grasses, such as tall fescue, and their livestock grazers or invertebrate pest herbivores. We tested the effects of Neotyphodium inhabiting introduced tall fescue and native Arizona fescue on preference, survival, and performance of the leaf-cutting ant, Acromyrmex versicolor, an important generalist herbivore in the southwestern United States. In a choice experiment, we determined preferences of foraging queens and workers for infected and uninfected tall fescue and Arizona fescue. In a no-choice experiment, we determined queen survival, worker production, and size of fungal gardens for foundress queens reared on diets of infected and uninfected tall fescue and Arizona fescue. Foraging workers and queens did not significantly prefer either uninfected tall fescue or Arizona fescue relative to infected grasses, although ants tended to harvest more uninfected than infected tall fescue and more infected than uninfected Arizona fescue. Queen survivorship and length of survival was greater on uninfected tall fescue, uninfected Arizona fescue, and infected Arizona fescue than on infected tall fescue or the standard diet of palo verde and mesquite leaves. No queens survived beyond 6 weeks of the study when fed the infected tall fescue diet, in contrast to the effects of the other diets. Likewise, worker production was much lower and fungal garden size much smaller on infected tall fescue than in all other treatments, including the standard diet. In general, ant colonies survived and performed better on uninfected tall fescue and infected and uninfected Arizona fescue than standard diets of palo verde and mesquite leaves. The interaction of Neotyphodium with its host grasses is highly variable and these endophytes may increase, not alter, or even decrease resistance to herbivores. The direction of the interaction depends on host and fungal genotype, herbivore species, and environmental factors. The presence of endophytes in most, if not all, host plants suggests that endophytes may alter foraging patterns, performance, and survival of herbivores, such as leaf-cutting ants, but not always in ways that increase host plant fitness.

Evidence supporting the occurrence of a new species of endophyte in some South American grasses

Endophytes of several South American grasses were examined. The taxonomic status of endophytes in Festuca argentina, F. hieronymi, Poa huecu, and an unidentified species of Poa is evaluated. On the basis of morphological features, and rDNA and protease gene sequence data, it is proposed that this endophyte is different from several other endophytes examined from North American, South American, and European species of Festuca and Poa. These endophytes, believed responsible for causing the ‘tembladera’ or ‘huecú’ toxicosis in animals, have also been reported to produce unique toxins. Isozyme analysis supports the distinctness of these endophytes but also demonstrates variability in populations with respect to gene polymorphisms. Taking all the data into consideration, we propose to establish a new endophyte species Neotyphodium tembladerae which includes endophytes found in multiple grass species. We suggest the use of a phylogenetic species concept to define species of Neotyphodium.

Evidence Supporting the Occurrence of a New Species of Endophyte in Some South American Grasses

Endophytes of several South American grasses were examined. The taxonomic status of en- dophytes in Festuca argentina, E hieronymi, Poa hue- cu, and an unidentified species of Poa is evaluated. On the basis of morphological features, and rDNA and protease gene sequence data, it is proposed that this endophyte is different from several other endo- phytes examined from North American, South Amer- ican, and European species of Festuca and Poa. These endophytes, believed responsible for causing the 'tembladera' or 'huecu' toxicosis in animals, have also been reported to produce unique toxins. Iso- zyme analysis supports the distinctness of these en- dophytes but also demonstrates variability in popu- lations with respect to gene polymorphisms. Taking all the data into consideration, we propose to estab- lish a new endophyte species Neotyphodium temblad- erae which includes endophytes found in multiple grass species. We suggest the use of a phylogenetic species concept to define species of Neotyphodium.

Nitrogen‐form and endophyte‐Infection effects on growth, nitrogen uptake, and alkaloid content of chewings fescue turf grass

Chewings fescue (Festuca rubra L. ssp. commutata Gaud) is naturally infected by an endophyte, however, little is known about the biology of this association and the effects on host fitness. A hydroponic study was conducted in the greenhouse to determine if endophyte and/or nitrogen (N) form influenced growth, N accumulation and alkaloid production in ‘Jamestown II’ Chewings fescue. Endophyte‐infected and non‐infected grasses were established in solution culture for 5 weeks using a 1/4 strength modified Hoagland solution, and then grown for 15 d in similar solutions containing 50 mg L‐1 of N as either NH4‐N, NO3 ‐N or a 1:1 mixture of NH4‐N and NO3 ‐N. The presence of the endophyte increased total biomass 54% in this grass, but growth was unaffected by N source. Nitrogen uptake was 58% higher in endophytic grasses, but no differences were observed in N use efficiency with respect to non‐endophytic grasses. Nitrogen form affected both N uptake and N use efficiency, with significantly higher values for plants growing in nutrient solutions containing NH4‐N. Endophytic grasses contained two alkaloids, ergovaline and peramine. Grasses grown with NH4‐N had significantly higher ergovaline levels than grasses receiving NO3‐N whereas N‐form had no effect on peramine. These results suggest that management factors, including N fertilization, might influence the production of specific alkaloids in endophyte‐infected grasses and potentially enhance resistance against insect pests.

Genetic Analysis of Biosynthesis and Roles of Anti-Herbivore Alkaloids Produced by Grass Endophytes

A characteristic of seed-borne clavicipitaceous symbionts (endophytes) that mediates their mutualisms with host grasses is production of anti-herbivore metabolites. Ergot alkaloids and indolediterpenes are potent neurotoxins in vertebrates ; saturated 1-aminopyrrolizidines (lolines) and the pyrrolopyrazine alkaloid, peramine, are active against insects. All except lolines are reported to be produced in cultures of fungal endophytes free of plant material. We identified lolines in defined-medium cultures of Neotyphodium uncinatum. We have also developed Epichloë festucae and Epichloë typhina as Mendelian genetic models to test the effects on aphids of lolines and peramine, respectively. In each case, the phenotypic difference of expression or non-expression was apparently governed by a single locus. Genotypes of E. typhina expressing peramine caused killing of greenbug aphid (Schizaphis graminum) on the host plants. Lolines were associated with killing of both greenbug and bird-cherry oat aphid (Rhopalosiphum padi). Statistically, the anti-aphid activities of the endophytes were entirely attributable to their alkaloids. Recent progress on genetic control of ergot alkaloid and indolediterpene expression holds promise for analogous tests for roles of these alkaloids in host benefits. Mendelian segregation and molecular knockouts can be used eventually to test the ecological importance of all known endophyte alkaloids in the many established endophyte effects, including increased drought tolerance, competitiveness, resistance to nematodes, and resistance to vertebrate and insect herbivores. Genetic knockouts in endophytes of genes for anti-vertebrate alkaloids will likely become an integral part of forage cultivar development.

Fungal Endophytes of Grasses in Japan : Benefits to the Host and Problems

Among the perennial ryegrass and tall fescue in Japan, the turf-type grasses, ecotype collections and imported grasses were found to be infected with Neotyphodium endophytes, but few commercial pasture-type grasses were infected. The occurrence of ryegrass stag-gers was limited to the beef cattles and cows which had been fed with the imported ryegrass straw. Therefore, it was strongly suggested that the ryegrass staggers occurring in Japan was caused by the imported endophyte-infected grasses. On the other hand, the endophyte-infected grasses showed feeding deterrence to insects such as bluegrass webworm and Tribolium confusum, and disease resistance to Bipolaris sorokiniana, Rhizoctonia solani, Drechslera dictyoides f. sp. perenne and so on. In Japan, Neotyphodium endophytes have been isolated from 27 species of cool-season grasses in 13 genera during the last three years, and most of them belonged to the subfamily Pooideae. Among the warm season grasses, Ephelis endophytes were detected in 15 species such as bermudagrass, Pangola-grass and paragrass. Paspalum thunbergii infected with Ephelis sp. showed feeding deterrence to a rice grass hopper, and Digitariaa decumbens (Pangola-grass) also had acquires tolerance to Japanese army worm (Pseudaletia separata) and grasshopper (Aiolopus thalassimus). However, the toxicity of the endophyte-infected grasses to animals is not known. It is important to know whether non-host plants acquired the resistance to insects and plant pathogens by artificial inoculation with fungal endophytes or not, which depends on the specificity between plant and endophyte associations. Here the compatibility and incompat-ibility between them are discussed.

Extraordinary ribosomal spacer length heterogeneity in a neotyphodium endophyte hybrid: implications for concerted evolution.

An extraordinary level of length heterogeneity was found in the ribosomal DNA (rDNA) of an asexual hybrid Neotyphodium grass endophyte, isolate Lp1. This hybrid Neotyphodium endophyte is an interspecific hybrid between two grass endophytes, Neotyphodium lolii, and a sexual form, Epichlöe typhina, and the length heterogeneity was not found in either of these progenitor species. The length heterogeneity in the hybrid is localized to the intergenic spacer (IGS) and is the result of copy-number variation of a tandemly repeated subrepeat class within the IGS, the 111-/119-bp subrepeats. Copy number variation of this subrepeat class appears to be a consequence of mitotic unequal crossing over that occurs between these subrepeats. This implies that unequal crossing over plays a role in the concerted evolution of the whole rDNA. Changes in the pattern of IGS length variants occurred in just two rounds of single-spore purification. Analysis of the IGS length heterogeneity revealed features that are unexpected in a simple model of unequal crossing over. Potential refinements of the molecular details of unequal crossing over are presented, and we also discuss evidence for a combination of homogenization mechanisms that drive the concerted evolution of the Lp1 rDNA.

FUNGAL ENDOPHYTES: A Continuum of Interactions with Host Plants

▪ Abstract Endophytic fungi living asymptomatically within plant tissues have been found in virtually all plant species. Endophytes are considered plant mutualists: They receive nutrition and protection from the host plant while the host plant may benefit from enhanced competitive abilities and increased resistance to herbivores, pathogens, and various abiotic stresses. Limited evidence also indicates that endophytes may influence population dynamics, plant community diversity, and ecosystem function. However, most of the empirical evidence for this mutualism and its ecological consequences has been based on a few agronomic grass endophytes. More recent studies suggest that endophyte-host plant interactions are variable and range from antagonistic to mutualistic. A more comprehensive view of the ecology and evolution of endophytes and host plants is needed. This article discusses how life history traits—such as fungal reproduction and pattern of infections and genotypic variation and ecological factors—influence the direction and strength of the endophyte-host plant interaction.

Double-stranded RNA and virus-like particles in the grass endophyte Epichloë festucae

Two double-stranded ribonucleic acid (dsRNA) elements were detected in an isolate of the clavicipitaceous grass endophyte Epichloe festucae obtained from an asymptomatic Festuca rubra plant. No dsRNA was detected in three other isolates of E. festucae. The size of the two dsRNA elements isolated from mycelium was of 5.2 and 3.2 kbp. Hybridization experiments with a cDNA probe complementary to the 5.2 kbp dsRNA showed that there was no sequence similarity between the dsRNA elements. Isometric virus-like particles of about 50 nm in diameter were observed by electron microscopy in sucrose-gradient purified virus preparations from the isolate containing dsRNA. The 5.2 kbp dsRNA element was present in the partially purified virus preparations, suggesting that this element is encapsidated. There was no difference with respect to growth rate or colony morphology between the dsRNA containing and dsRNA-free isolates. The presence of dsRNA and virus-like particles suggests the presence of a mycovirus in the Vit5 strain of E. festucae.

A new group of endophytes in European grasses

SummaryPoaceae of subfamily Festucoideae frequently harbour endophytic, symbiotic fungi in their aerial parts. Isolations were made from 21 different species of Poaceae, belonging mainly to the genera Lolium and Festuca. Pure cultures of 45 fungal isolates were obtained. Morphology, isozyme and molecular analysis showed the presence of three groups of endophytes. Most of the isolates could be accommodated with the previously described species of Neotyphodium and Epichloë (the e endophytes). Two new endophytes isolated from Koeleria cristata and Melica ciliata were shown to belong to this group. Gliocladium like and Phialophora like isolates were obtained from Lolium perenne and Festuca gigantea respectively (the p endophytes). Nine isolates especially those from annual Lolium produced rod like conidia. These isolates belong to Acremonium sensu stricto and are morphologically similar to Acremonium chilense.

Nutritional requirements for growth of fungal endophytes of grasses

Fifteen isolates of fungal endophytes of grasses were studied for their ability to metabolize different sources of carbon and nitrogen. These endophytes had been isolated from 12 different species of Poaceae and included Clavicipitaceae with or without a teleomorph (genera Epichloë and Neotyphodium, respectively) and species belonging to the genus Acremonium sensu stricto (Acremonium chilense-like). Pectin and cellulose as carbon sources and tryptophan and methionine as nitrogen sources appeared to support poorly the growth of most isolates. Hexoses, disaccharides, complex nitrogen sources, asparagine, and glutamine supported growth of all isolates. The isolates of genus Neotyphodium were characterized by limited growth whatever the substrate, the inhibition of their growth by high concentrations of glucose and fructose, and their inability to assimilate pentoses (xylose, arabinose) and nitrates. The isolates of genus Epichloë showed better growth than those of the previous group and their growth was not inhibited by high concentrations of glucose, but they were also unable to use pentoses. The Acremonium chilense-like isolates showed rapid growth and were distinguished by their ability to use the pentoses and nitrates. In contrast, they showed relatively poor growth on methionine and alanine as nitrogen sources. They showed the most rapid growth on high concentrations of glucose or fructose.Key words: carbon sources, nitrogen sources, Neotyphodium, Epichloë, Acremonium, grass endophytes.