Changes in ovarian function in mature beef cows grazing endophyte infected tall fescue

The objective was to examine follicular and luteal development and function in mature, lactating beef cows grazing endophyte free (E-) or endophyte infected (E+) tall fescue during the early postpartum period. Angus, Hereford, and Angus x Hereford cows were exposed to pasture for 37-39 days before synchronized estrus. Serum concentrations of prolactin were evaluated during the luteal phase before the synchronized estrus. Every Monday, Wednesday, and Friday for one estrous cycle ovaries were monitored by transrectal ultrasonography and blood was collected for determination of serum concentrations of progesterone and estradiol in cows that responded to synchronization. Signs of fescue toxicosis in E+ cows included decreased serum concentrations of prolactin (84.9+/-13.6 pg/ml versus 32.3+/-12.0 pg/ml; P < 0.009) measured during the luteal phase (day 37 of grazing) and decreased body condition of cows and weight of cows and calves (P < 0.001). Neither serum concentrations of progesterone or estradiol, nor diameter of the CL differed between treatments. Diameter of the largest follicle tended to be smaller for cows grazing E+ fescue, especially between days 8 and 12 of the estrous cycle (P < 0.08). Numbers of class 1 (3-5 mm) and class 3 (>10 mm) follicles were similar (P > 0.05) between treatments, but number of class 2 (6-9 mm) follicles was reduced in E+ cows for most of the cycle (days 10 through 20; P < 0.03). Length of synchronized estrous cycle, days open, calving interval, and pregnancy rate at 30, 45, 60, and 90 days post-breeding was similar (P > 0.05) among treatment groups. Even though follicular dynamics (diameter of the largest follicle and number of class 2 follicles) were altered in cows grazing E+ tall fescue, follicular function was apparently not affected by ergot alkaloids.     

The effect of feeding endophyte infected tall fescue seed on reproductive performance in female rats

Female Sprague-Dawley rats (Rattus norvegicus) were randomly assigned to diets containing mixtures of rat chow and tall fescue (Festuca arundinacea) seed with 0, 5, 10, 20 and 40% infection levels of Acremonium coenophialum to assess the effect of the diets on the reproductive potential of rats. Rats fed 40% infected seed had decreased body weight, decreased mean percent body weight of uteri, failed to maintain normal estrous cycles and were unable to become pregnant. Animals fed a diet of 20% infected fescue seed had extended estrous cycles. There were no significant differences among the 0, 5 and 10% dietary treatments.     

Leaf endophyte Neotyphodium coenophialum modifies mineral uptake in tall fescue

Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin, a fungal endophyte found primarily in shoots of tall fescue (Festuca arundinacea Shreb.), can modify rhizosphere activity in response to phosphorus (P) deficiency. In a controlled environment experiment, two cloned tall fescue genotypes (DN2 and DN4) free (E-) and infected (E+) with their naturally occurring endophyte strains were grown in nutrient solutions at low P (3.1 ppm) or high P (31 ppm) concentrations for 21 d. Endophyte infection increased root dry matter (DM) of DN4 by 21% but did not affect root DM of DN2. Under P deficiency, shoot and total DM were not affected by endophyte but relative growth rate was greater in E+ than E- plants. In high P nutrient solution, E+ plants produced 13% less (DN2) or 29% more (DN4) shoot DM than E- plants. Endophyte affected mineral concentrations in roots more than in shoots. Regardless of P concentration in nutrient solution, E+ DN2 accumulated more P, Ca, Zn and Cu but less K in roots than E- plants. When grown in high P nutrient solution, concentrations of Fe and B in roots of E+ DN2 plants were reduced compared with those of E- plants. Concentrations of P, Ca and Cu in roots of DN4 were less, but K was greater in E+ than E- plants. In shoots, E+ DN2 had greater concentrations of Fe and Cu than E- DN2, regardless of P concentration in nutrient solution. Genotype DN4 responded to endophyte infection by reducing B concentration in shoots. Nutrient uptake rates were affected by endophyte infection in plants grown in low P nutrient solution. A greater uptake rate of most nutrients and their transport to shoots was observed in DN2, but responses of DN4 were not consistent. Results suggest that endophyte may elicit different modes of tall fescue adaptation to P deficiency. This revised version was published online in June 2006 with corrections to the Cover Date.     

内生真菌感染对宿主植物高羊茅锌耐受性的影响

以感染内生真菌(Neotyphodium coenophialum)和未感染内生真菌的高羊茅(Festuca arundinacea Schreb.)为实验材料,在营养液中加入ZnSO4进行锌胁迫实验,分析内生真菌对宿主植物锌耐受性的影响。与未感染内生真菌的植株相比,内生真菌感染对高羊茅的总生物量没有显著增益作用,但增加了分蘖数和叶片延伸生长累积值。内生真菌感染降低了高羊茅中Zn2+的总含量,改变了锌在高羊茅中的分配,增加叶鞘中锌的含量,减少叶片中锌的含量。在高锌浓度下,内生真菌感染对净光合速率的变化没有影响,但是显著提高了其宿主的PSⅡ光化学效率(Fv/Fm)。总体来看,内生真菌感染改善宿主高羊茅的锌耐受性。     

不同浓度和形态磷处理下内生真菌感染对高羊茅的影响

以感染内生真菌(endophyte-infected,EI)和不感染内生真菌(endophyte-free,EF)的高羊茅(Festuca arundinacea Schreb.)为材料,在温室沙培条件下研究内生真菌对高羊茅适应缺磷及利用不同形态磷肥的影响。结果表明,1)缺磷条件下,高羊茅EI和EF植株生长差异不显著;正常供磷条件下,高羊茅EI植株拥有更多分蘖数和绿叶数。说明正常供磷条件下内生真菌改善了宿主高羊茅的生长。2)与水溶性磷相比,高羊茅根有机酸和酸性磷酸酶(acid phosphatase,APase)活性在难溶性磷条件下显著增加,而根总酚含量无显著变化。在水溶性磷条件下,高羊茅EI植株根总酚含量显著高于EF植株,此时EI植株比EF植株拥有更多分蘖数和绿叶数,说明在水溶性磷条件下内生真菌对宿主地上部生长具有一定贡献。在难溶性磷条件下,虽然高羊茅EI植株根总酚含量仍然高于EF植株,但同时EI植株根有机酸含量显著低于EF植株,因此内生真菌感染只是增大了宿主植物的根冠比,而对分蘖数和绿叶数等无显著影响,说明内生真菌对宿主利用难溶性磷贡献不大。可见,内生真菌对宿主植物的生长在水溶性磷条件下更有利。     

Varying endophyte status and energy supplementation of fresh tall fescue in continuous culture

Eight dual-flow continuous culture vessels (700 ml) were used to compare in vitro effects of toxic, endophyte-infected (E+), endophyte-free (E−), and non-toxic, endophyte-infected (EN) Jesup tall fescue (vegetative stage) on ruminal fermentation at 4 levels (0, 150, 300, and 450 g kg⁻¹ DM) of concentrate supplementation (ground corn) for a total of 12 experimental diets in a randomized incomplete block design with 2 replicates. Each culture vessel was offered a total of 15 g DM d⁻¹. Forage was fed in four equal portions (fed at 03:00, 09:00, 15:00, and 21:00 h); and corn was fed in two equal portions (fed at 09:00 and 21:00 h). Headspace gas and liquid samples were analyzed for methane, ruminal culture pH, ammonia–N, and volatile fatty acid production. Ammonia–N output (g d⁻¹) varied by grass; EN had lower values compared to those of E+ and E−. Increasing the level of grain linearly decreased ruminal culture pH, ammonia–N, acetate production, and the acetate-to-propionate ratio, whereas propionate and butyrate production increased with higher grain supplementation. Ruminal fermentation was minimally altered by the presence of the endophyte; however, for the highest level of grain fed (450 g kg⁻¹ DM fed) the methane production pattern for all three grasses was altered. In addition to having the lowest ruminal ammonia–N accumulation, the non-toxic, endophyte-infected fescue resulted in the lowest methane production measured.     

Effects of feeding endophyte infected tall fescue seed on reproductive performance of female CD-1 mice via competitive breeding

This study was conducted to determine the effects of feeding endophyte-infected (Acremonium coenophialum ) tall fescue (Festuca arundinacea ) seed on the growth and reproductive performance of female CD-1 mice via competitive breeding. One hundred sixty female mice were randomly allocated to groups of ten and fed one of two diets. Diet 1 consisted of 50% mouse chow and 50% noninfected Ky-31 tall fescue seed (w/w). Diet 2 contained 50% chow and 50% tall fescue seed that was 80% infected with A. coenophialum . After 50 d of preconditioning on their respective diets, a single male was introduced into each group of 10 females and allowed to cohabitate for 96 h. The males were removed after the cohabitation period and the females continued through gestation on their respective diets. Body weight of dams and litter weights were recorded at parturition. There were no differences (P>0.05) in pregnancy rates between dietary Treatments 1 and 2 (50% vs 48.8%, respectively). However, the average number of pups born per litter (11.10 pups) and average total litter weight (17.21 g) was greater for those females consuming Diet 1 than for females consuming Diet 2 (9.33 pups per litter and 13.97 g total litter weight). The incidence of dead and cannibalized pups was more frequent with Diet 2 than Diet 1 (0.13 vs 0.0 dead; 0.21 vs 0.03 cannibalized, respectively). The obtained data suggest that although the pregnancy rate was similar between the two dietary treatments, the reproductive capacity (litter size and litter weight) of female CD-1 mice was affected by the consumption of endophyte infected fescue seed.     

Distribution of fungal endophyte genotypes in doubly infected host grasses

Fungal endophytes of the genus Epichloë live intercellulary in above ground plant parts of many pooid ‘grasses of the temperate regions. The associations are characterized by single genotype entities since a given host individual normally contains a single endophyte genotype. They can persist over the life span of the hosts. This study examines whether two fungal genotypes can co-exist within a host plant, and how fungal genotypes are distributed within a host in the case of double infections. We selected four Epichloë bromicola strains that we identified as unique genotypes through RAPD‘ analysis. Young Bromus erectus plants, derived from callus cultures, were artificially inoculated with all possible double-strain mixtures of these fungal genotypes. For identification of fungal genotypes in planta, we designed genotype-specific primer pairs that flanked size-variable loci in the fungal genomes. Diagnostic PCR revealed that only one fungal genotype was present in most inoculated plants, but double infections were also observed with a frequency of 8% of all infected plants. Subsequent analyses of individual tillers of doubly infected plants revealed that, in a given tiller, both the leaf-blade and the leaf-sheath were colonized with only one endophyte genotype. Tillers without any detectable fungal DNA were also observed. Thus, co-existence of multiple endophyte genotypes within a single host plant is governed by mutual exclusion at the tiller level.     

Susceptibility of tall fescue to Rhizoctonia zeae infection as affected by endophyte symbiosis

Endophytic fungi belonging to the genus Neotyphodium often form symbiotic associations with grasses. The host plants usually benefit from the association with an endophyte. Presence of the symbiont may increase host resistance to infection by some pathogens. However, the exact mechanism of the lower susceptibility of endophyte‐infected plants to diseases is still unclear. Growth chamber trials were conducted to determine whether (a) tall fescue plants infected with the endophyte Neotyphodium coenophialum (E+) are more resistant to sheath and leaf spot disease caused by Rhizoctonia zeae than endophyte‐free (E?) plants, and (b) R. zeae growth inhibition is associated with endophyte presence. Tall fescue genotypes, each symbiotic with a genetically different native endophyte strain, were inoculated with isolates of R. zeae. The tillers infection by R. zeae, density of endophyte hyphae and content of total phenolic compounds in tillers were studied. Antifungal activity of the N. coenophialum towards R. zeae, Rhizoctonia solani, Bipolaris sorokiniana and Curvularia lunata was also investigated in dual‐culture assays. For Tf3, Tf4, TfA2 and TfA9 tall fescue genotypes, the E+ plants had reduced R. zeae infection. In the Tf9 and Tf8085 genotypes, R. zeae infection was similar for both E+ and E? plants. The strongest effect was observed for the Tf4 endophyte. A strongly positive correlation (r = 0.94) occurred between endophyte hyphal density and disease index across all tall fescue genotypes. Dual‐culture assays showed no inhibitory interaction between the seven endophyte strains and the R. zeae isolates; however, some endophytes inhibited R. solani, B. sorokiniana and C. lunata. Endophyte presence increased the production of phenolic compounds by the host grasses. The level of phenolics also differed significantly depending on the time of analysis after inoculation of plants by R. zeae. The results indicate that N. coenophialum can suppress disease severity caused by R. zeae infection. The mechanism of higher resistance of E+ plants is likely not based on direct inhibition such as antibiosis or competition. Thus, the induction of specific mechanisms in the host plant, for example, production of phenolic compounds, seems to be the main way of providing resistance to the grass by the endophyte.     

Procedure for isolating the endophyte from tall fescue and screening isolates for ergot alkaloids

A procedure was developed to isolate and determine ergot alkaloid production by Acremonium coenophialum, the endophytic fungus of tall fescue. The procedure established that macerated leaf sheath or pith from inflorescence stem placed either in a liquid medium or on a corn meal-malt extract agar medium produced isolated mycelium and characteristic conidia within a 3- to 3.5-week period. Once isolated, each fungus was placed in another liquid medium, M104T, where competent strains produced total ergot alkaloids ranging from 38 to 797 mg/liter. Several isolates were negative for ergot alkaloid synthesis. The production of ergot alkaloids by individual isolates was unstable; isolates rapidly degenerated in their ability to produce ergot alkaloids during subculture. However, the procedure as presented allows the assessment of an isolate for ergot alkaloid synthesis during its initial isolation.     

Use of tall fescue EST-SSR markers in phylogenetic analysis of cool-season forage grasses.

Microsatellites or simple sequence repeats (SSRs) are highly useful molecular markers for plant improvement. Expressed sequence tag (EST)-SSR markers have a higher rate of transferability across species than genomic SSR markers and are thus well suited for application in cross-species phylogenetic studies. Our objectives were to examine the amplification of tall fescue EST-SSR markers in 12 grass species representing 8 genera of 4 tribes from 2 subfamilies of Poaceae and the applicability of these markers for phylogenetic analysis of grass species. About 43% of the 145 EST-SSR primer pairs produced PCR bands in all 12 grass species and had high levels of polymorphism in all forage grasses studied. Thus, these markers will be useful in a variety of forage grass species, including the ones tested in this study. SSR marker data were useful in grouping genotypes within each species. Lolium temulentum, a potential model species for cool-season forage grasses, showed a close relation with the major Festuca-Lolium species in the study. Tall wheat grass was found to be closely related to hexaploid wheat, thereby confirming the known taxonomic relations between these species. While clustering of closely related species was found, the effectiveness of such data in evaluating distantly related species needs further investigations. The phylogenetic trees based on DNA sequences of selected SSR bands were in agreement with the phylogenetic relations based on length polymorphism of SSRs markers. Tall fescue EST-SSR markers depicted phylogenetic relations among a wide range of cool-season forage grass species and thus are an important resource for researchers working with such grass species.     

Assessing short-term responses of prokaryotic communities in bulk and rhizosphere soils to tall fescue endophyte infection

In contrast to endophyte-free (E−) tall fescue, endophyte-infected (E+) tall fescue pastures appear to enhance soil carbon sequestration. A hypothetical mechanism that may account for the enhanced carbon sequestration is that the E+ tall fescue affects the soil microbial community or components of it that are involved in organic carbon turnover. A 60-week mesocosm study with a factorial arrangement of soil type, loamy sand (LS) and clay loam (CL), and E+ and E− tall fescue was conducted to determine if the soil microbial communities were affected by the presence of the endophyte. Bulk and rhizosphere soil samples were fixed in paraformaldehyde, and prepared for total direct microbial counts, and with a combination of one of a domain or subdivision fluorescent oligonucleotide probe for enumerating metabolically active Eubacteria, bacterial subdivisions, and Archaea. E+ tall fescue suppressed the archaeal and high G+C gram-positive bacterial communities of the bulk CL, the delta-proteobacterial community in the rhizosphere CL, and the Planctomycetes community of the rhizosphere LS. In the long-term, suppression of these microbial communities may be a factor in enhanced soil carbon sequestration associated with E+ tall fescue.     

Procedure for isolating the endophyte from tall fescue and screening isolates for ergot alkaloids.

A procedure was developed to isolate and determine ergot alkaloid production by Acremonium coenophialum, the endophytic fungus of tall fescue. The procedure established that macerated leaf sheath or pith from inflorescence stem placed either in a liquid medium or on a corn meal-malt extract agar medium produced isolated mycelium and characteristic conidia within a 3- to 3.5-week period. Once isolated, each fungus was placed in another liquid medium, M104T, where competent strains produced total ergot alkaloids ranging from 38 to 797 mg/liter. Several isolates were negative for ergot alkaloid synthesis. The production of ergot alkaloids by individual isolates was unstable; isolates rapidly degenerated in their ability to produce ergot alkaloids during subculture. However, the procedure as presented allows the assessment of an isolate for ergot alkaloid synthesis during its initial isolation.     

Endophyte-mediated resistance to black cutworm as a function of plant cultivar and endophyte strain in tall fescue

To improve Neotyphodium endophyte-mediated resistance to black cutworm Agrotis ipsilon (Hufnagel) (BCW), a series of experiments was conducted by using several different cultivars of tall fescue, Schedonorus arundinaceus (Schreb.) Dumort. in combination with several different haplotypes of the endophyte Neotyphodium coenophialum (Morgan-Jones & Gams) (plant cultivar × endophyte haplotype = plant line), each producing unique alkaloid profiles. BCW settling response, survival at 5 and 10 d, and larval biomass varied significantly among plant lines. In general, greater variation BCW performance was observed within a single plant cultivar infected with different endophyte haplotypes than among different plant cultivars infected with the same endophyte haplotype, but comparisons among the former were far more numerous. Although five endophyte-mediated alkaloids representing three alkaloid classes were quantified in the plants, the pyrrolizidine alkaloid N-acetyl norloline was consistently the single best predictor of BCW performance. BCW settling response, 5-d survival, and 10-d survival decreased as levels of the alkaloid N-acetyl norloline increased. The same three response variables also decreased with increasing levels of peramine, but increased with increasing levels of ergovaline. Minor variation in endophyte infection levels occurring among infected plant lines had no significant influence on BCW performance. Results indicate a potentially important role for N-acetyl norloline and peramine in providing resistance to black cutworm whereas ergovaline appears to be much less important. Therefore, endophyte haplotypes expressing high levels of N-acetyl norloline and peramine may be of particular importance for developing 'friendly' endophyte-enhanced turf and pasture grasses that resist challenging lepidopteran pests, although remaining safe for wildlife and grazing mammals.     

Water use and water-use efficiency of the invasive Centaurea maculosa and three native grasses

The Eurasian herb Centaurea maculosa Lam. has invaded millions of hectares of semi-arid grasslands in western North America. Its success may reflect that it may be more competitive than native species, it is not grazed by large herbivores, it was introduced without its native enemies, it may interfere with native species via allelopathy, or most likely some combination of these factors. Greater competitive ability could include greater use of limiting soil resources, such as water, or more efficient use of soil water, thereby inhibiting establishment, survival, and reproduction of native species. We measured water use and water-use efficiency of Centaurea and three native grasses, Pseudoroegneria spicata [Scribn. and Smith] A. Love, Pascopyrum smithii [Rybd.] A. Love, and Festuca idahoensis Elmer, in a glasshouse. Water-use efficiency was determined by the traditional measure of biomass produced per mass of water used, and by carbon-isotope discrimination (). Centaurea did not use the most water, or use water more efficiently (based on biomass (g)/ water (kg) and carbon-isotope discrimination) than all three native grasses. We also determined carbon-isotope discrimination of Centaurea and dominant native grasses during the 1999 and 2000 growing seasons at three field sites. Centaurea rosettes had the lowest water-use efficiency (greatest carbon-isotope discrimination), followed by mature plants of Centaurea, and then native grasses. Water-use efficiency of mature Centaurea plants and native grasses was greater in late summer than early summer. Centaurea's success as an invasive species in North America cannot be attributed to greater use of soil water or greater water-use efficiency than native grasses.     

Dynamics of Neotyphodium endophyte infection in ageing seed pools: incidence of differential viability loss of endophyte,infected seed and non-infected seed

Symbiotic associations between grasses and vertically transmitted endophytic fungi are widespread in nature. Within grass populations, changes in the frequency of infected plants are driven by influence of the endophyte on the fitness of their hosts and by the efficiency of endophyte transmission from parent plants to their offspring. During the seed stage, the endophyte might influence the fitness of its host by affecting the rate of seed viability loss, whereas the efficiency of endophyte transmission is affected by losses of viability of the fungus within viable seeds. We assessed the viability losses of Lolium multiflorum seeds with high and low level of infection of the endophyte Neotyphodium occultans, as well as the loss of viability of the fungus itself, under accelerated seed ageing and under field conditions. Starting with high endophyte-infected accessions of L. multiflorum, we produced their low endophyte-infected counterparts by treating seeds with a fungicide, and subsequently multiplying seeds in adjacent plots allowing pollen exchange. In our accelerated ageing experiments, which included three accessions, high endophyte-infected seeds lost viability significantly faster than their low endophyte-infected counterpart, for only one accession. High endophyte-infected seeds of this particular accession absorbed more water than low endophyte-infected seeds. In contrast, the endophyte lost viability within live seeds of all three accessions, as the proportions of viable seeds producing infected seedlings decreased over time. In our field experiment, which included only one accession, high endophyte-infected seed lost viability significantly but only slightly faster than low endophyte-infected seed. In contrast, the loss of viability of the endophyte was substantial as the proportions of viable seeds producing infected seedlings decreased greatly over time. Moving the seeds from the air to the soil surface (simulating seed dispersion off the spikes) decreased substantially the rate of seed viability loss, but increased the rate of endophyte viability loss. Our experiments suggest that, in ageing seed pools, endophyte viability loss and differential seed mortality determine decreases in the proportions of endophyte-infected seeds in L. multiflorum. Endophyte viability loss within live seeds contributes substantially more to infection frequency changes than differential viability losses of infected and non-infected seeds.     

Agrobacterium-mediated high efficiency transformation of tall fescue (Festuca arundinacea)

Tall fescue (Festuca arundinacea) is the predominant cool-season pasture grass in the USA. Embryogenic calluses were induced from seeds/caryopsis of elite tall fescue cultivars Jesup and Kentucky-31, and were broken up into small pieces and used for Agrobacterium tumefaciens-mediated transformation. Agrobacterium strains LBA4404 and EHA105 harboring pCAMBIA vectors or the super-binary vector pTOK233 were used to infect the embryogenic callus pieces. The number of hygromycin resistant calluses obtained per dish of infected callus pieces was in the range of 2.0-5.8, and the number of transgenic plants recovered per dish of infected callus pieces was in the range of 0.4-1.7. When transformation efficiency was calculated based on the number of transgenic plants recovered and the number of original intact calluses used, the transformation frequency was in the range of 1.9-8.7%. The use of the easily available pCAMBIA vectors could produce equivalent results as the superbinary vector pTOK233. The transgenic nature of the regenerated plants was demonstrated by Southern hybridization analysis using undigested and digested genomic DNA samples. Expression of the transgenes was confirmed by northern hybridization analysis, GUS staining, and detection of GFP signals. Fertile transgenic plants were obtained after vernalization in the greenhouse. Progeny analysis revealed Mendelian inheritance of the transgenes.     

Volatile compounds of endophyte-free and infected tall fescue (Festuca arundinacea Schreb.).

Volatile compounds produced by intact plants and ground leaf tissue from endophyte-infected (E+) and endophyte-free (E-) tall fescue (Festuca arundinacea Schreb.) were collected by a purge-and-trap procedure and analyzed by gas chromatography/mass spectrometry The volatile compound profile from ground leaf tissue was similar between E+ and E- clonal plants; however, the sheaths of E+ clonal plants produced higher levels of 1-octen-3-ol, a characteristic volatile compound derived from lipid peroxidation in fungi, which was absent in E- clonal plants. Intact plants produced fewer volatiles than macerated leaves. At 25 degrees C, (Z)-3-hexen-1-ol acetate was the most abundant compound, accounting for 77 and 89% of the total volatile emission from E+ and E- plants, respectively. Higher temperature (32 degrees C) significantly reduced the production of (Z)-3-hexen-1-ol acetate. Nonanal was the most abundant compound at 32 degrees C accounting for 52 and 45% of the total volatile emission from E+ and E- plants. Treatment of E+ and E- plants with jasmonic acid (JA) dramatically altered the volatile compound profile. The levels of (E)-beta-ocimene increased more than 200-fold and accounted for at least 43% of the total volatile emission. Although the presence of endophyte resulted in some qualitative and quantitative differences in the production of volatile compounds, they are unlikely to account for the differences in insect resistance between E+ and E- plants. Nevertheless, the production of a unique spectrum of volatiles after JA treatment may represent a significant plant-based defense response in tall fescue that is independent of endophyte.