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Rebecca L Mcculley - One of the best experts on this subject based on the ideXlab platform.
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tall fescue cultivar and fungal Endophyte combinations influence plant growth and root exudate composition
Frontiers in Plant Science, 2015Co-Authors: Rebecca L Mcculley, David H McnearAbstract:Tall fescue (Lolium arundinaceum (Schreb.)) is a cool-season perennial grass used in pastures throughout the Southeastern United States. The grass can harbor a shoot-specific fungal Endophyte (Epichloe coenophiala) thought to provide the plant with enhanced resistance to biotic and abiotic stresses. Because alkaloids produced by the common variety of the Endophyte cause severe animal health issues, focus has been on replacing the common-toxic strain with novel varieties that do not produce the mammal-toxic alkaloids but maintain abiotic and biotic stress tolerance benefits. Little attention has been given to the influence of the plant-fungal symbiosis on rhizosphere processes. Therefore, our objective was to study the influence of this relationship on plant biomass production and root exudate composition in tall fescue cultivars PDF and 97TF1, which were either not infected with the Endophyte (E-), infected with the common toxic Endophyte (CTE+) strain or with one of two novel Endophytes (AR542E+, AR584E+). Plants were grown sterile for three weeks after which plant biomass, total organic carbon, total phenolic content and detailed chemical composition of root exudates were determined. Plant biomass production and exudate phenolic and organic carbon content were influenced by Endophyte status, tall fescue cultivar, and their interaction. GC-TOF MS identified 132 compounds, including lipids, carbohydrates and carboxylic acids. Cluster analysis showed that the interaction between Endophyte and cultivar resulted in unique exudate profiles. This is the first detailed study to assess how Endophyte infection, notably with novel Endophytes, and tall fescue cultivar interact to influence root exudate composition. Our results illustrate that tall fescue cultivar and Endophyte status can influence plant growth and root exudate composition, which may help explain the observed influence of this symbiosis on rhizosphere biogeochemical processes.
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Fungal Endophyte presence and genotype affect plant diversity and soil-to-atmosphere trace gas fluxes
Plant and Soil, 2013Co-Authors: Javed Iqbal, Jim A. Nelson, Rebecca L McculleyAbstract:Aims Novel fungal Endophyte (Neotyphodium coenophialum; Latch, Christensen and Samuels; Glenn, Bacon, and Hanlin) genotypes in symbiosis with tall fescue (Lolium arundinaceum; Schreb. Darbysh.) have been recently introduced to agricultural seed markets. These novel Endophytes do not produce the full suite of toxins that the ‘common toxic’ form does, and therefore, may not have the same consequences on plant and soil processes. Here, we evaluated the effects of Endophyte presence and genotype on ecosystem processes of tall fescue stands.
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Fungal Endophyte presence and genotype affect plant diversity and soil-to-atmosphere trace gas fluxes
Plant and Soil, 2013Co-Authors: Javed Iqbal, Jim A. Nelson, Rebecca L McculleyAbstract:Aims Novel fungal Endophyte ( Neotyphodium coenophialum ; Latch, Christensen and Samuels; Glenn, Bacon, and Hanlin) genotypes in symbiosis with tall fescue ( Lolium arundinaceum ; Schreb. Darbysh.) have been recently introduced to agricultural seed markets. These novel Endophytes do not produce the full suite of toxins that the ‘common toxic’ form does, and therefore, may not have the same consequences on plant and soil processes. Here, we evaluated the effects of Endophyte presence and genotype on ecosystem processes of tall fescue stands. Methods We quantified the effects of the presence of the common toxic Endophyte (CT), two novel Endophyte genotypes (AR-542, AR-584), no Endophyte (Endophyte free, E-), and a mixture of all Endophyte statuses (mix) within a single genotype of tall fescue (PDF) on various soil and plant parameters. Results Endophyte presence and genotype affected tall fescue cover and plant species diversity: cover—CT, AR-542, AR -584, mix > E- and species diversity—E- > AR-542, AR -584 > CT, mix. Most measured soil parameters had significant Endophyte effects. For example, higher fluxes of soil CO_2 and N_2O were measured from stands of AR-542 than from the other Endophyte treatments. Conclusions These results indicate that Endophyte presence and genetic identity are important in understanding the ecosystem-scale effects of this agronomically important grass-fungal symbiosis.
Elizabeth A Arnold - One of the best experts on this subject based on the ideXlab platform.
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endohyphal bacterium enhances production of indole 3 acetic acid by a foliar fungal Endophyte
PLOS ONE, 2013Co-Authors: Michele T Hoffman, Malkanthi K Gunatilaka, Kithsiri Wijeratne, Leslie Gunatilaka, Elizabeth A ArnoldAbstract:Numerous plant pathogens, rhizosphere symbionts, and endophytic bacteria and yeasts produce the important phytohormone indole-3-acetic acid (IAA), often with profound effects on host plants. However, to date IAA production has not been documented among foliar Endophytes -- the diverse guild of primarily filamentous Ascomycota that live within healthy, above-ground tissues of all plant species studied thus far. Recently bacteria that live within hyphae of Endophytes (endohyphal bacteria) have been detected, but their effects have not been studied previously. Here we show not only that IAA is produced in vitro by a foliar Endophyte (here identified as Pestalotiopsis aff. neglecta, Xylariales), but that IAA production is enhanced significantly when the Endophyte hosts an endohyphal bacterium (here identified as Luteibacter sp., Xanthomonadales). Both the Endophyte and the Endophyte/bacterium complex appear to rely on an L-tryptophan dependent pathway for IAA synthesis. The bacterium can be isolated from the fungus when the symbiotic complex is cultivated at 36°C. In pure culture the bacterium does not produce IAA. Culture filtrate from the Endophyte-bacterium complex significantly enhances growth of tomato in vitro relative to controls and to filtrate from the Endophyte alone. Together these results speak to a facultative symbiosis between an Endophyte and endohyphal bacterium that strongly influences IAA production, providing a new framework in which to explore Endophyte-plant interactions.
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geographic locality and host identity shape fungal Endophyte communities in cupressaceous trees
Fungal Biology, 2008Co-Authors: Michele T Hoffman, Elizabeth A ArnoldAbstract:Abstract Understanding how fungal Endophyte communities differ in abundance, diversity, taxonomic composition, and host affinity over the geographic ranges of their hosts is key to understanding the ecology and evolutionary context of Endophyte–plant associations. We examined Endophytes associated with healthy photosynthetic tissues of three closely related tree species in the Cupressaceae ( Coniferales ): two native species within their natural ranges [ Juniperus virginiana in a mesic semideciduous forest, North Carolina (NC); Cupressus arizonica , under xeric conditions, Arizona (AZ)], and a non-native species planted in each site ( Platycladus orientalis ). Endophytes were recovered from 229 of 960 tissue segments and represented at least 35 species of Ascomycota . Isolation frequency was more than threefold greater for plants in NC than in AZ, and was 2.5 (AZ) to four (NC) times greater for non-native Platycladus than for Cupressus or Juniperus . Analyses of ITS rDNA for 109 representative isolates showed that Endophyte diversity was more than twofold greater in NC than in AZ, and that Endophytes recovered in AZ were more likely to be host-generalists relative to those in NC. Different Endophyte genera dominated the assemblages of each host species/locality combination, but in both localities, Platycladus harboured less diverse and more cosmopolitan Endophytes than did either native host. Parsimony and Bayesian analyses for four classes of Ascomycota ( Dothideomycetes , Sordariomycetes , Pezizomycetes , Eurotiomycetes ) based on LSU rDNA data ( ca 1.2 kb) showed that well-supported clades of Endophytes frequently contained representatives of a single locality or host species, underscoring the importance of both geography and host identity in shaping a given plant's Endophyte community. Together, our data show that not only do the abundance, diversity, and taxonomic composition of Endophyte communities differ as a function of host identity and locality, but that host affinities of those communities are variable as well.
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diversity and host range of foliar fungal Endophytes are tropical leaves biodiversity hotspots
Ecology, 2007Co-Authors: Elizabeth A Arnold, Francois LutzoniAbstract:Fungal Endophytes are found in asymptomatic photosynthetic tissues of all major lineages of land plants. The ubiquity of these cryptic symbionts is clear, but the scale of their diversity, host range, and geographic distributions are unknown. To explore the putative hyperdiversity of tropical leaf Endophytes, we compared Endophyte communities along a broad latitudinal gradient from the Canadian arctic to the lowland tropical forest of central Panama. Here, we use molecular sequence data from 1403 Endophyte strains to show that Endophytes increase in incidence, diversity, and host breadth from arctic to tropical sites. Endophyte communities from higher latitudes are characterized by relatively few species from many different classes of Ascomycota, whereas tropical Endophyte assemblages are dominated by a small number of classes with a very large number of endophytic species. The most easily cultivated Endophytes from tropical plants have wide host ranges, but communities are dominated by a large number of rare species whose host range is unclear. Even when only the most easily cultured species are considered, leaves of tropical trees represent hotspots of fungal species diversity, containing numerous species not yet recovered from other biomes. The challenge remains to recover and identify those elusive and rarely cultured taxa with narrower host ranges, and to elucidate the ecological roles of these little-known symbionts in tropical forests.
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canopy cover and leaf age affect colonization by tropical fungal Endophytes ecological pattern and process in theobroma cacao malvaceae
Mycologia, 2003Co-Authors: Elizabeth A Arnold, Edward Allen HerreAbstract:Fungal Endophytes inhabit healthy tissues of all terrestrial plant taxa studied to date and are diverse and abundant in leaves of tropical woody an- giosperms. Studies have demonstrated that plant lo- cation and leaf age influence density of Endophyte infection in leaves of tropical forest trees. However, ecological factors underlying these observations have not been explored in detail. Here, we establish that foliar Endophytes of a tropical tree (Theobroma cacao, Malvaceae) are transmitted horizontally and that en- dophyte-free seedlings can be produced for experi- mental manipulation by protecting aerial tissues from surface wetting. At Barro Colorado Island, Panama, we used transects of Endophyte-free seedlings to de- termine the importance of several factors (canopy cover, abundance of aerial and epiphytic propagules, leaf age, leaf chemistry, leaf toughness and duration of exposure to viable air spora) in shaping coloniza- tion by endophytic fungi. Endophytes colonized leaves of T. cacao more rapidly beneath the forest canopy than in cleared sites, reflecting local abun- dance of aerial and epiphytic propagules. The dura- tion of exposure, rather than absolute leaf age, influ- enced Endophyte infection, whereas leaf toughness and chemistry had no observed effect. Endophytes isolated from mature T. cacao grew more rapidly on media containing leaf extracts of T. cacao than on media containing extracts from other co-occurring tree species, suggesting that interspecific differences in leaf chemistry influence Endophyte assemblages. Together, these data allow us to identify factors un- derlying patterns of Endophyte colonization within healthy leaves of this tropical tree.
G. Venkatesan - One of the best experts on this subject based on the ideXlab platform.
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Endophytic fungal communities in woody perennials of three tropical forest types of the Western Ghats, southern India
Biodiversity and Conservation, 2011Co-Authors: T. S. Suryanarayanan, T. S. Murali, N. Thirunavukkarasu, M. B. Govinda Rajulu, G. Venkatesan, R. SukumarAbstract:Fungal Endophytes of tropical trees are expected to be exceptionally species rich as a consequence of high tree diversity in the tropics and the purported host restriction among the Endophytes. Based on this premise, Endophytes have been regarded as a focal group for estimating fungal numbers because their possible hyperdiverse nature would reflect significantly global fungal diversity. We present our consolidated ten-year work on 75 dicotyledonous tree hosts belonging to 33 families and growing in three different types of tropical forests of the NBR in the Western Ghats, southern India. We conclude that Endophyte diversity in these forests is limited due to loose host affiliations among Endophytes. Some Endophytes have a wide host range and colonize taxonomically disparate hosts suggesting adaptations in them to counter a variety of defense chemicals in their hosts. Furthermore, such polyphagous Endophytes dominate the Endophyte assemblages of different tree hosts. Individual leaves may be densely colonized but only by a few Endophyte species. It appears that the environment (the type of forest in this case) has a larger role in determining the Endophyte assemblage of a plant host than the taxonomy of the host plant. Thus, different tropical plant communities have to be studied for their Endophyte diversity to test the generalization that Endophytes are hyperdiverse in the tropics, estimate their true species richness, and use them as a predictor group for more accurate assessment of global fungal diversity.
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Fungal Endophyte communities in two tropical forests of southern India: diversity and host affiliation
Mycological Progress, 2007Co-Authors: T. S. Murali, T. S. Suryanarayanan, G. VenkatesanAbstract:Fifteen tree species from a tropical dry thorn forest and fifteen tree species from a tropical dry deciduous forest in the Mudumalai Wildlife Sanctuary, Nilgiri Biosphere Reserve, southern India, were surveyed for their foliar Endophyte communities during the dry and wet seasons. Surface sterilized leaf segments of uniform dimension were plated on nutrient agar and culturable Endophytes growing from the segments were identified. Endophyte diversity was greater in the dry thorn forest than in the dry deciduous forest in the dry season. Although the isolation frequency of culturable Endophytes increased for both forests during the wet season, the assemblages were represented not by any unique fungal species but by the commonly occurring ones. Furthermore, although individual leaves were densely colonized by Endophytes, only a few species of Endophytes colonized the whole leaves; and, only a few fungal species dominated the foliar endophytic communities and were common for both forests during both dry and wet seasons. Thus, even under wet conditions that favour dispersal and infection by fungi, the Endophyte diversity increased only marginally, an indication that certain tropical forests are not hyperdiverse with reference to fungal Endophytes. This should be considered when using culturable Endophyte diversity as a surrogate for estimating global fungal diversity.
Kari Saikkonen - One of the best experts on this subject based on the ideXlab platform.
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The Effects of Endophytes on Seed Production and Seed
2020Co-Authors: Meadow Fescue, Kari SaikkonenAbstract:Fungal Endophytes of grasses are often included in agricultural management and in ecological studies of natural grass populations. In European agriculture and ecological studies, however, grass Endophytes are largely ignored. In this study, we determined Endophyte infection frequencies of 1 3 European cultivars and 49 wild tall fescue (Schedonorus phoenix) populations in Northern Europe. We then examined seed production and seed predation of Endophyte-infected (E+) and Endophyte-free (E-) tall fescue (in wild grass populations and in a field experiment) and meadow fescue (Schedonorus pratensis; in a field experiment only). Endophytes were detected in only one of the 13 cultivars. In contrast, >90% of wild tall fescue plants harbored Endophytes in 45 wild populations but were absent in three inland populations in Estonia. In three wild tall fescue study sites, 17%, 22%, and 56% of the seeds were preyed upon by the cocksfoot moth. Endophyte infection did not affect seed mass of tall fescue in the field experiment. However, seed predation was lower in E+ than E- grasses in the two tall fescue populations with higher predation rates. For meadow fescue, the mean number of seeds from E+ plants was higher than E- plants, but E- and
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Chemical Ecology Mediated by Fungal Endophytes in Grasses
Journal of Chemical Ecology, 2013Co-Authors: Kari Saikkonen, Pedro E. Gundel, Marjo HelanderAbstract:Defensive mutualism is widely accepted as providing the best framework for understanding how seed-transmitted, alkaloid producing fungal Endophytes of grasses are maintained in many host populations. Here, we first briefly review current knowledge of bioactive alkaloids produced by systemic grass-Endophytes. New findings suggest that chemotypic diversity of the Endophyte-grass symbiotum is far more complex, involving multifaceted signaling and chemical cross-talk between Endophyte and host cells ( e.g. , reactive oxygen species and antioxidants) or between plants, herbivores, and their natural enemies ( e.g. , volatile organic compounds, and salicylic acid and jasmonic acid pathways). Accumulating evidence also suggests that the tight relationship between the systemic Endophyte and the host grass can lead to the loss of grass traits when the lost functions, such as plant defense to herbivores, are compensated for by an interactive endophytic fungal partner. Furthermore, chemotypic diversity of a symbiotum appears to depend on the Endophyte and the host plant life histories, as well as on fungal and plant genotypes, abiotic and biotic environmental conditions, and their interactions. Thus, joint approaches of (bio)chemists, molecular biologists, plant physiologists, evolutionary biologists, and ecologists are urgently needed to fully understand the Endophyte-grass symbiosis, its coevolutionary history, and ecological importance. We propose that Endophyte-grass symbiosis provides an excellent model to study microbially mediated multirophic interactions from molecular mechanisms to ecology.
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Symbiotic interactions as drivers of trade-offs in plants: effects of fungal Endophytes on tall fescue
Fungal Diversity, 2013Co-Authors: Pedro E. Gundel, Marjo Helander, Lucas A. Garibaldi, Kari SaikkonenAbstract:Studying the controls on biomass allocation trade-offs in plants are important since they affect harvestable product yields and are critical to understanding symbiotic interactions. Epichloae fungal Endophytes associate with cool-season grasses, growing systemically within the plant inter-cellular spaces and are transmitted through seeds. We explore the Endophytes influence on the relationship between the plant reproductive and vegetative aboveground biomass (reproductive effort: RE) and on the trade-off between two components of the reproductive biomass, number and weight of panicles (RPN), using tall fescue as a model system. Naturally Endophyte-colonized, manipulatively Endophyte-free, and naturally Endophyte-free plants from Northern European wild-populations together with the cultivar Kentucky-31 were grown under different environmental conditions (nutrients x water). The Endophyte had an effect on the RPN (E+: 6.19, ME-: 4.68 and E-: 4.40) which indicates how reproductive biomass is partitioned into number and mass of panicles, but not on RE (≈0.06). As expected, wild plants showed higher reproductive effort (≈0.06) compared to the cultivar KY-31 (0.05), irrespective of Endophyte presence. Endophyte-colonized plants had lighter panicles than Endophyte-free plants, a pattern that was clear among low-yielding plants. Similarly, the trade-off between RPN and RE was higher for Endophyte-colonized plants. This was again evident among plants with low RE indicating that colonized plants split the yield into either greater number of panicles and/or lighter panicles. The effect of vertically transmitted Endophytes has earlier been studied as ratios (e.g. RE); however, our study shows that this approach may hide size-dependent Endophyte effects on these relationships. Our study reveals that Neotyphodium Endophyte affects trade-offs in tall fescue plants in a complex manner, and is influenced by a number of biological and abiotic factors.
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genetic compatibility determines Endophyte grass combinations
PLOS ONE, 2010Co-Authors: Kari Saikkonen, Piippa R Wali, Marjo HelanderAbstract:Even highly mutually beneficial microbial-plant interactions, such as mycorrhizal- and rhizobial-plant exchanges, involve selfishness, cheating and power-struggles between the partners, which depending on prevailing selective pressures, lead to a continuum of interactions from antagonistic to mutualistic. Using manipulated grass-Endophyte combinations in a five year common garden experiment, we show that grass genotypes and genetic mismatches constrain genetic combinations between the vertically (via host seeds) transmitted Endophytes and the out-crossing host, thereby reducing infections in established grass populations. Infections were lost in both grass tillers and seedlings in F1 and F2 generations, respectively. Experimental plants were collected as seeds from two different environments, i.e., meadows and nearby riverbanks. Endophyte-related benefits to the host included an increased number of inflorescences, but only in meadow plants and not until the last growing season of the experiment. Our results illustrate the importance of genetic host specificity and trans-generational maternal effects on the genetic structure of a host population, which act as destabilizing forces in Endophyte-grass symbioses. We propose that (1) genetic mismatches may act as a buffering mechanism against highly competitive Endophyte-grass genotype combinations threatening the biodiversity of grassland communities and (2) these mismatches should be acknowledged, particularly in breeding programmes aimed at harnessing systemic and heritable Endophytes to improve the agriculturally valuable characteristics of cultivars.
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Defensive mutualism between plants and endophytic fungi?
Fungal Diversity, 2010Co-Authors: Kari Saikkonen, S. Saari, M. HelanderAbstract:Endophyte-grass symbiosis is generally considered to be a classic example of microbe-plant symbiosis in which the fitness of the microbial symbiont and its host plant is closely linked, and thus, presumed to align the interests of partners toward mutually beneficial cooperation. Accumulating evidence seems to suggest that defensive mutualism provides the best framework for understanding plant-Endophyte interactions in general. We conducted a meta-analysis of 99 published studies on 36 plant (inc. both grass and tree species), 62 herbivore and 17 predator or parasitoid taxons to test the importance of defensive mutualism in multitrophic interactions. In general, statistical perusal revealed that we still know little about these seemingly well-studied biological interactions. The conceptual framework for Endophyte-grass interactions has largely been based on Endophyte-plant-herbivore studies of two, economically important, artificially selected and introduced agricultural grass species, tall fescue and perennial ryegrass, and two generalist invertebrate pests. Only 10 original publications provided data of higher trophic levels. Consistent with the defensive mutualism hypothesis, the meta-analysis indicates that Endophytes slightly increase grass resistance to herbivores, and the defensive mutualism appears to be most commonly detected in systemic and vertically transmitted grass Endophytes compared to horizontally transmitted tree Endophytes. However, variation appears to increase when higher trophic levels are considered. In addition to taxonomical bias, the literature is strongly biased toward short-term laboratory and greenhouse experiments rather than field conditions. Thus, current literature is insufficient to capture the breadth of variability inherent in the wild grass-Endophyte populations and communities, and the general importance of defensive mutualism remains to be solved in future studies.
Michael J. Christensen - One of the best experts on this subject based on the ideXlab platform.
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high nitrogen supply and carbohydrate content reduce fungal Endophyte and alkaloid concentration in lolium perenne
New Phytologist, 2007Co-Authors: Susanne Rasmussen, Wayne R Simpson, Michael J. Christensen, A J Parsons, Shalome A Bassett, D E Hume, Linda J Johnson, Richard D Johnson, Christina Stacke, Christine R VoiseyAbstract:Summary • The relationship between cool-season grasses and fungal Endophytes is widely regarded as mutualistic, but there is growing uncertainty about whether changes in resource supply and environment benefit both organisms to a similar extent. • Here, we infected two perennial ryegrass (Lolium perenne) cultivars (AberDove, Fennema) that differ in carbohydrate content with three strains of Neotyphodium lolii (AR1, AR37, common strain) that differ intrinsically in alkaloid profile. We grew Endophyte-free and infected plants under high and low nitrogen (N) supply and used quantitative PCR (qPCR) to estimate Endophyte concentrations in harvested leaf tissues. • Endophyte concentration was reduced by 40% under high N supply, and by 50% in the higher sugar cultivar. These two effects were additive (together resulting in 75% reduction). Alkaloid production was also reduced under both increased N supply and high sugar cultivar, and for three of the four alkaloids quantified, concentrations were linearly related to Endophyte concentration. • The results stress the need for wider quantification of fungal Endophytes in the grassland–foliar Endophyte context, and have implications for how introducing new cultivars, novel Endophytes or increasing N inputs affect the role of Endophytes in grassland ecosystems.
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Infection of tall fescue and perennial ryegrass plants by combinations of different Neotyphodium Endophytes.
Fungal Biology, 2000Co-Authors: Michael J. Christensen, Wayne R Simpson, T. Al SamarraiAbstract:Individual tall fescue (Festuca arundinacea) plants infected with both Neotyphodium coenophialum and N. lolii Endophytes, and individual perennial ryegrass (Lolium perenne) plants infected with both N. lolii and Neotyphodium LpTG-2, were obtained following inoculation of naturally infected seedlings with the second Endophyte. Differences in the ability of the Endophytes to produce conidia, together with colony characteristics, enabled the Endophytes in plants to be identified following incubation of excised leaf tissue on potato dextrose agar. Most tillers of dually infected plants were infected with just a single Endophyte, but tillers infected with two Endophytes were identified in three tall fescue plants. In these tillers one Endophyte was always present at a much higher concentration than the other. Over time the incidence of dually infected tillers decreased and no tillers with both N. coenophialum and N. lolii were present 5 months after the associations were established. No evidence was obtained of exchange of nuclei between different Endophytes present in dually infected tillers giving rise to heterokaryons or interspecific hybrids.
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variation in the ability of acremonium Endophytes of lolium perenne festuca arundinacea and f pratensis to form compatible associations in the three grasses
Fungal Biology, 1995Co-Authors: Michael J. ChristensenAbstract:The ability of representative isolates of six recognized taxonomic groups (TGs) of Acremonium Endophytes from perennial rye-grass, tall fescue and meadow fescue to form compatible associations following inoculation of seedlings of the three grasses was examined. The six TGs were not specific to their natural hosts and most representative isolates formed associations with all three host species. Incompatibility resulting in hyphal death was noted in A. coenophialum -perennial rye-grass associations. Incompatibility affecting host tissue, resulting in stunted tillers with necrosis in the region of the apical meristem, was present in associations of tall fescue with either A. uncinatum or LpTG-2 ( Lolium perenne TG-2). Some associations were unstable with Endophyte-free tillers being produced as plants developed. This instability was not confined to Endophyte-grass associations showing either of the two types of histological incompatibility reactions. The compatibility of Endophyte-grass associations was not related to the percentage of successfully inoculated seedlings obtained. This study provides further evidence that the association between Acremonium Endophytes and their host grasses is complex.