Acremonium Typhinum Research Articles

Identification of the fungal endophyte of Ammophila breviligulata (American beachgrass) as Epichloë amarillans.

The grass Ammophila breviligulata (American beachgrass) is known to host an endophyte of the genus Epichloë. Based on morphological characteristics it was originally identified as Acremonium typhinum var. ammophilae and is currently designated as Epichloë typhina var. ammophilae. However, the Epichloë species has not previously been identified based on DNA sequence data. Based on phylogenetic placement of beta-tubulin and translation elongation factor 1-alpha DNA sequences the endophyte is identified as a member of E. amarillans rather than E. typhina.

5443981 Acremonium typhinum atcc 74228 which exhibits endoproteolytic activity : Belanger Faith C; Lindstrom Jon T East Brunswick, NJ, United States assigned to Rutgers the State University

5443981 Acremonium typhinum atcc 74228 which exhibits endoproteolytic activity : Belanger Faith C; Lindstrom Jon T East Brunswick, NJ, United States assigned to Rutgers the State University

Purification and Characterization of an Endophytic Fungal Proteinase That Is Abundantly Expressed in the Infected Host Grass.

A novel Acremonium typhinum proteinase that is expressed during endophytic infection of the grass Poa ampla Merr. was purified from endophyte-infected leaf sheath tissue. It is a thiol-containing serine alkaline endoproteinase with bound carbohydrate. In the infected host tissue, this proteinase is an abundant protein localized within fungal membrane vesicles and in the plant and/or fungal cell walls. This proteinase was not expressed constitutively during fungus culture. Rather, its expression appeared to be induced by nutrient depletion. Expression of an antigenically similar proteinase was detected in five other endophyte-infected Poa species. The regulated expression of the proteinase in culture and its abundance in infected plant tissue suggest that its expression may be involved in the symbiotic interaction of the plant and the fungus.

Mechanism and Rate of Sugar Uptake by Acremonium typhinum, an Endophytic Fungus Infecting Festuca rubra: Evidence for Presence of a Cell Wall Invertase in Endophytic Fungi

Fungal endophytes of the genus Acremonium infect many grass species. They exist in the intercel? lular spaces of the aerial plant parts, most abundantly in the leaf sheaths. They therefore must obtain all of their nutrients from the apoplastic spaces in the plant. This report is the first comprehensive, biochemically based study of sugar uptake by Acremonium spp. The endophytes (Acremonium typhinum) were isolated from Festuca rubra plants and were grown in culture. Indi? vidual colonies were incubated in the presence of (U- 14C)radiolabeled glucose, fructose, or sucrose for 20 minutes and the uptake quantified by scintillation counting. The uptake rates for all three sugars were biphasic, indicating two distinct mechanisms of trans- port. At low sugar concentrations (below 10 mM) the uptake was saturable and had the characteristics of a carrier-mediated mechanism. At high sugar concen? trations (10-100 mM) the uptake was linear suggesting diffusion as the predominant mechanism of uptake. From competition experiments (uptake of labeled sug? ar in the presence of a different unlabeled sugar) it appeared that there were separate carriers for glucose and fructose. Two mechanisms for sucrose uptake were detected, a sucrose carrier and hexose uptake as a result of cell wall invertase. Cell wall invertase activity of the fungal isolates was inducible by growing the fungi on sucrose containing media.

Mechanism and rate of sugar uptake byAcremonium typhinum, an endophytic fungus infectingFestuca rubra:Evidence for presence of a cell wall invertase in endophytic fungi

Mechanism and rate of sugar uptake by<i>Acremonium typhinum</i>, an endophytic fungus infecting<i>Festuca rubra:</i>Evidence for presence of a cell wall invertase in endophytic fungi

A Novel Fungal Protease Expressed in Endophytic Infection of Poa Species.

The fungus Acremonium typhinum produces a novel endoprotease during symbiotic endophytic infection of the grass, Poa ampla. This protease is unusual because it is highly active in the presence of sodium dodecyl sulfate. The enzyme is a thiol-containing serine protease and is localized to a crude membrane fraction. Similar protease activity has been detected in endophyte-infected Poa autumnalis and Poa sylvestris plants. Expression of this protease may be important in endophytic infection of Poa spp., because similar activity has not been detected in endophyte-infected Festuca arundinacea or Lolium perenne.

Molecular genetics of Epichloë typhina and Acremonium coenophialum

The close associations between grasses and endophytes, whereby the fungi constitute maternally inherited components of the symbiotic entities (symbiota), make genetic engineering and other genetic manipulations of the endophytes an attractive approach to improvement of forage, pasture and turfgrass cultivars. A number of protective alkaloids are produced by the endophytes. Although insecticidal, nematocidal and antimicrobial metabolites produced by the mycosymbionts are desirable agronomic characteristics, anti-mammalian activities which are problematic for livestock farmers need to be mitigated. As a necessary prerequisite for endophyte genetic engineering, the authors have developed a transformation protocol for the tall fescue symbiont Acremonium coenophialum Morgan-Jones et Gams. The approach used was to introduce the antibiotic resistance gene, hph, which was obtained from the bacterium Escherichia coli and modified in vitro to allow expression in fungi. Successful incorporation of this ‘chimeric’ gene into the fungal genome was detected by resistance of the transformants to hygromycin B and by DNA hybridization analysis. The wide variation in the amounts and/or types of protective alkaloids produced by different isolates of Epichloë typhina (Fr.) Tulasne ( Acremonium typhinum Morgan-Jones et Gams), and other Acremonium spp., raises the prospect of employing the sexual cycle of E. typhina as an alternative genetic system for development of new endophyte strains. However, there is a lack of phenotypically variable characters to follow in Mendelian crosses. Therefore, restriction fragment length polymorphisms should be identified and used for genetic mapping. Preliminary studies of this approach are presented. Genetic manipulations and other approaches to cultivar development based on the endophytes should be done with an understanding of their evolutionary biology and the basis for host preference. Previous studies have added much to the understanding of the alkaloid production potential of different isolates, and the degree of host specificity of both choke pathogens and non-pathogenic endophytes. This paper presents a phylogenetic analysis using DNA sequence information. The results support four conclusions: (1) the endophytes have evolved from E. typhina; (2) the endophytes do not have a strict coevolutionary relationship with their grass hosts; (3) loline production, characteristic of certain symbiota, is not a good indicator of phylogenetic affinities of the fungal symbionts; (4) there is a close relationship between isolates of A. coenophialum from tall fescue, and Acremonium lolii Latch, Samuels et Christensen from perennial ryegrass and a non-pathogenic A. typhinum from red fescue.

Endophyte-Host Associations in Grasses. XVII. Ecological and Physiological Features CharacterizingEpichloë Typhinaand Some Anamorphic Varieties in England

Field research was conducted in central England on grasses infected by Epichloë typhina. Both asymptomatic and stromata-producing infections were encountered and examined. Isolations of endophytes were made and comparative laboratory studies conducted on sugar utilization capacities, starch and protein hydrolysis capacities, and cultural morphologies. The presence of distinct varieties of Acremonium typhinum is proposed to account for variation in ecology, physiology, and morphology of isolates.

Endophyte-Host Associations in Grasses. XVII. Ecological and Physiological Features Characterizing Epichloe typhina and Some Anamorphic Varieties in England

Field research was conducted in central England on grasses infected by Epichloë typhina. Both asymptomatic and stromata-producing infections were encountered and examined. Isolations of endophytes were made and comparative laboratory studies conducted on sugar utilization capacities, starch and protein hydrolysis capacities, and cultural morphologies. The presence of distinct varieties of Acremonium typhinum is proposed to account for variation in ecology, physiology, and morphology of isolates.

ENDOPHYTE‐HOST ASSOCIATIONS IN GRASSES. XVI. PATTERNS OF ENDOPHYTE DISTRIBUTION IN SPECIES OF THE TRIBE AGROSTIDEAE

Distribution of Acremonium endophytes in several species of Agrostideae is determined through surveys conducted in the field and in grass herbaria. Widespread geographic distribution of Acremonium in a particular grass species may indicate early colonization of the grass as a host, while a narrow pattern of geographic distribution suggests more recent colonization of the grass. Two grasses that appear to show a narrow endophyte distribution include Agrostis alba and Ammophila breviligulata. Cultural features of endophytes from several grasses are compared. A new variety of Acremonium typhinum is proposed to accommodate the endophyte from A. breviligulata. An endophyte in Agrostis alba is identified as Acremonium starrii. It is also suggested that Acremonium endophytes are spreading in grasses and may be progressively colonizing new hosts.

Endophyte-Host Associations in Forage Grasses. XIV. Primary Stromata Formation and Seed Transmission in Epichloe typhina: Developmental and Regulatory Aspects

Fungus/host interactions during primary stroma formation were investigated for Acremonium typhinum in Agrostis hiemalis and Elymus canadensis and found to be essentially the same in both grasses. In Festuca obtusa, where no primary conidial stroma or perithecial Epichloe typhina stroma are formed, A. typhinum is seed transmitted and has a similar habit to A. coenophialum in Festuca arundinacea. Experiments were conducted to determine the possible role of sugar utilization capacity in regulating stromata formation.

The ?-tubulin gene of Epichlo� typhina from perennial ryegrass (Lolium perenne)

Epichloë typhina is a biotrophic fungal pathogen which causes choke disease of pooid grasses. The anamorphic state, Acremonium typhinum, is placed in the section Albo-lanosa along with related, mutualistic, seed-disseminated endophytes. As an initial study of gene structure and evolution in Epichloë and related endophytes, the beta-tubulin gene, tub2, of the perennial ryegrass choke pathogen (EtPRG) was cloned and sequenced. The coding sequence and the predicted beta-tubulin amino acid sequence were highly homologous to the Neurospora crassa homologs, and to one of the two beta-tubulin genes of Emericella nidulans. However, two introns characteristic of the N. crassa and Em. nidulans genes were absent in the E. typhina gene. Furthermore, one of the remaining introns possessed the uncommon 5' splice junction, GC. In contrast to published observations concerning other Ascomycetes, a mutant of EtPRG, selected for resistance to methyl-2-benzimidazole carbamate (benomyl), possessed no alteration of its beta-tubulin coding sequence.

Acremonium typhinum Identified as an Endophyte in Blue Fescue

Acremonium typhinum Identified as an Endophyte in Blue Fescue

Steroid metabolites of Acremonium coenophialum, an endophyte of tall fescue

Three Acremonium coenophialum metabolites, ergosterol, ergosterol peroxide, and ergosta-4,6,8. (14);22-tetraen-3-one, were isolated from field-grown, fungus-infected. (toxic) tall fescue and mycelium grown in vitro. Mycelium contained 10 J.Lg of total steroljmg dry weight of tissue, with ergosterol comprising 40% of the total sterols. Mycelium contained EP only when grown in the light. EP was toxic to brine shrimp, two bacterial species, and chick embryos. Whether EP is involved in tall fescue toxicity is not known, but it was the only toxic compound found in chloroform-methanol extracts from both fungus-infected fescue and laboratory-grown mycelium and EP was not found in nontoxic tall fescue. Cattle grazed on Kentucky 31 tall fescue (Festuca arundinaceae Schreb.) during the often exhibit symptoms known collectively as summer syndrome. These symptoms include reduced weight gain, rough hair coat, slightly elevated temperature, excessive salivation, rapid breathing, and excitability (Hoveland et al., 1983). Although syndrome was previously associated with hot weather, recent research has shown that poor weight gain occurs throughout the grazing season when cattle feed on tall fescue infected with an endophytic fungus (Hoveland et al., 1983). Bacon et al. (1977) isolated the endophytic fungus Epichloe typhina (Fr.) Tulasne from bent grass. The imperfect (Anamorphic) stage of this fungus is Acremonium typhinum Morgan-Jones and Gams. The endophytic fungus isolated from tall fescue in Alabama, Georgia, Kentucky, Texas, and New Zealand (Morgan-Jones and Gams, 1982; Latch et al., 1984; White and Cole, 1985, 1985b) has been classified as A. coenop­ hialum Morgan-Jones and Gams; a perfect (teleomorphic) state has never been reported on tall fescue. According to Morgan-Jones (personal communication), the endo­ phytic anamorphs from bent grass and tall fescue differ morphologically as well as in host specificity. In our view, the fungus endophyte of tall fescue is A. coenophialum Morgan-Jones and Gams and all other names are errone­ ous. It has often been suggested that alkaloids are a likely cause of fescue foot and perhaps other problems associated

Endophyte-Host Associations in Forage Grasses. I. Distribution of Fungal Endophytes in Some Species ofLoliumandFestuca

Several species of (e.g., Lolium temulentum L., L. remotum Schranck, L. perenne L.) and two species of fescue (i.e., tall fescue, Festuca arundinacea Schreb. and red fescue, F. rubra L.) have long been known to harbor fungal endophytes (Vogl, 1898; Neubauer and Remer, 1902; McLennan, 1920; Neill, 1940, 1941; Sampson, 1933). The endophyte found in perennial (L. perenne) growing in certain pastures of New Zealand (Sampson, 1935,1937; Neill, 1940, 1941; Lloyd, 1959) is considered to be the source of a toxin causing a condition in cattle and sheep known as ryegrass staggers (Hetcher and Harvey, 1981; Fletcher, 1982). This syndrome is particularly severe when animals feed on drought-stressed pastures in which the dominant grass species is the endophytebearing L. perenne. Fescue toxicity syndrome of cattle, an apparently sporadic but serious problem in many parts ofthe United States where tall fescue is grown as forage, was originally thought to be associated with the clavicipitaceous, sys? temic phytopathogen, Epichloe typhina (Fr.) Tul. (Bacon et al, 1977), a fungus known to cause choke, or cat-tail disease in a broad spectrum of grasses (Sprague, 1950). The anamorph of E. typhina was recently described and given the binominal Acremonium typhinum by Morgan-Jones and Gams (1982), who demon? strated that this fungus and the tall fescue endophyte are different microorganisms. The authors identified the latter as a previously undescribed anamorph of the same genus {A. coenophialum Morgan-Jones and Gams), which they isolated from seeds and culms of F. arundinacea. This endophyte has no known teleomorph. It is apparently A. coenophialum which is consistently present in tall fescue on which grazing cattle have fed and developed fescue toxicosis (Bacon et al, 1911 Jones, 1981; Schmidt et al, 1982). Data on the distribution of fungal endophytes in forage grasses is at best fragmentary. A concerted effort is necessary to identify those grasses that contain endophytes, and to determine if toxic properties of a certain species of grass correlate with the presence of the endophyte. The purpose of this report is to provide evidence that fungal endophytes in Festuca and Lolium are even more common than originally suspected. A simple method for detection of the fungal endophyte in grass seeds has been described by Clark et al (1983). We have used this procedure to examine seeds of Lolium and Festuca obtained from the Lundell Herbarium (LL) ofthe University of Texas at Austin for the presence of endophytic hyphae (Table I). Most species of grasses examined have not been reported pre? viously as hosts for an endophytic fungus. A minimum of five seeds was examined from each herbarium collection.