Acremonium Coenophialum Research Articles

Feeding Preferences and Changes in Mass of Canada Geese Grazing Endophyte-Infected Tall Fescue

In the late 1940s and 1950s southern farmers began planting a newly-discovered tall fescue cultivar (Kentucky-3 1), which was much hardier and more productive than other cultivars. Unknown at the time, this cultivar was infected with the endophytic fungus Acremonium coenophialum. By the 1910s there were over 14 million ha of tall fescue pastures in the U.S., mostly in the southern and south-central states, and most were infected with the fungus (Shelbv and Dalrvmule 1987. Stuedemann and Ho>eland 1988). The total infected area may have increased recently, because tall fescue has been the predominant grass seeded in Conservation Reserve Program plantings in the central and southern

A Test for Constitutive and Induced Resistance by Tall Fescue (Festuca arundinacea) to an Insect Herbivore: Impact of the Fungal Endophyte, Acremonium coenophialum

-Endophytic fungi living within some grasses have been shown to increase resistance of their host plants to insect herbivores. We tested the hypothesis that endophytes also mediate induced resistance by a grass to an herbivorous insect. Tall fescue (Festuca arundinacea), both infected and uninfected with the endophyte, Acremonium coenophialum, was artificially damaged by clipping a tiller from each plant four weeks after germination. We used the fall armyworm (Spodoptera frugiperda) as a bioassay to determine the affects of our treatments. Fall armyworm larvae were reared by feeding them shoot and stem material of damaged and undamaged plants in a two factor (infection status and damage) design. Eight-day-old larvae weighed less and took longer to develop into adults when fed endophyteinfected vs. endophyte-free plant material. However, the interaction between status and damage was not statistically significant. In contrast, pupae weighed more when fed infected vs. endophyte-free plant material and the interaction between infection status and damage had a marginally significant effect on pupal mass (F1,177 = 32.2; P = 0.05). Pupae reared from damaged infected plants weighed less than those reared from undamaged infected plants. No pattern with damage was apparent for insects reared on endophyte-free plants. Our results suggest that the clipping damage may result in an induced response in plants infected with the fungal endophyte.

Does Endophyte Influence Regrowth of Tall Fescue?

The influence of ecological and environmental factors on the response of the mutualistic symbionts Acremonium coenophialum(Morgan-Jones and Gams), and tall fescue ( Festuca arundinacea, Schreb.) has received substantial attention. However, much of what is known about developmental and physiological responses has been obtained from static or mature canopies and the influence of defoliation on the symbiota has not been considered in detail. A controlled environment experiment was conducted to assess the influence of defoliation and endophyte on the regrowth and development of two tall fescue genotypes and their respective endophytes, known to differ in morphology and alkaloid production capacity. The response of endophyte infected relative to non-infected plants was evaluated for measured and calculated parameters for each defoliation. While the influence of genotype was substantial on virtually all parameters, endophyte interacted with genotype and defoliation resulting in enhanced plasticity of mutualists as a response to varying conditions. Endophyte infection influenced leaf mass depending upon genotype, while the relative benefit of endophyte on pseudostem mass was affected by defoliation. Endophyte interacted with genotype to influence relative growth rate and productivity relative to nitrogen concentration when canopies were clipped, but was less important when canopies remained uncut. In some instances endophyte gave growth and size advantage to the host and did not in others. Generalities regarding symbiont response to extrinsic factors may be misleading, since responses depend upon the specific mutualism considered and conditions imposed.

Some effects of water potential upon endophyticAcremoniumspp. in culture

Acremonium coenophialum, A. starrii, and A. typhinum were grown on potato dextrose agar (PDA) amended with KC1 (PDA + KC1) or sucrose (PDA + S) to attain a wide range of osmotic water potentials. Radial growth was greatest between -0.3 MPa (PDA without amendment) and -3.0 to -4.0 MPa, below which growth diminished to near zero at -8 MPa. Acremonium isolates grew well on corn

Performance by Stocker Cattle Offered Feedstuffs Containing Acremonium coenophialum and Supplemented with Aspergillus oryzae Fermentation Extract

An experiment was conducted to evaluate the effects of supplemental Aspergillus oryzae fermentation extract (AO) on intake, gain, temperature, and serum prolactin levels of steers fed seed screenings with and without Acremonium coenophialum. Sixty-four Angus and Angus × Hereford crossbred steers were allotted randomly by weight into one of 16 groups and fed an A. coenophialum-free hay basal diet offered for ad libitum consumption. Groups were assigned randomly to one of four treatments in a 2 × 2 factorial arrangement Treatments consisted of 2.0 kg/d seed screenings from either bromegrass (B) or A. coenophialum-infected fescue (F; 677 μg/kg ergovaline). Within each screenings type, 0.9 kg/d of a soybean hull-mineral supplement was offered either with 2g per head per d AO or no AO (C) for 90 d beginning on June 30. Steers fed B gained 15.6kg more (P<0.01) weight, consumed 0.7 kg/d more (P<0.01) DM, and converted DM to gain more efficiently (P<0.01) than those fed F. A screening type × sampling date interaction was detected (P<0.05) for rectal temperatures and serum prolactin levels. Steers fed B had lower (P<0.01) rectal temperatures on July 27 and tended (P<0.10) to have lower temperatures on September 7 and 21 than those fed F. Serum prolactin levels were higher (P<0.05) on September 21 and 28, and tended (P<0.10) to be higher on July 27 from cattle receiving B than from those receiving F. Supplementation with AO did not affect gain, intake, or feed conversion. Rectal temperatures from steers fed AO tended (P<0.10) to be higher than temperatures of those fed C on July 13 and August 11. Therefore, consumption of A. coenophialum-infected tall fescue screenings resulted in typical fescue toxicosis symptoms, but A. oryzae fermentation extract did not overcome these symptoms.

Effects of Niacin and Aspirin on Performance Parameters in Heifers Fed Endophyte-Infected Tall Fescue

Cattle grazing endophyte-(Acremonium coenophialum) infected tall fescue perform poorly because of the adverse effects of endophyte toxicosis. One of the manifestations of this toxicosis is elevated body temperature caused by an inability to dissipate body heat Niacin has vasodilatory activity and has shown a beneficial heat dissipation effect in some animal species. Aspirin affects body temperature via prostaglandin synthesis and may be beneficial in alleviating high body temperature induced by consumption of endophyte-infected fescue. To evaluate these two compounds, 20 beef heifers, stratified by weight, were allotted to one of four treatments: LE: low-endophyte fescue hay HEC: endophyte-infected hay (70% infestation rate), HEN: endophyte-infected hay plus 2g niacin/d, and HEA: endophyte-infected hay plus 200mg aspirin/kg BW per d. Neither aspirin nor niacin was effective in lowering body temperatures vs HEC. Heifers fed HEA had maximum body temperatures that were higher (P<0.01) than both the HEC and LE groups. Heifers fed HEN had body temperatures that were higher (P<0.01) than those of LE-treated heifers but not different (P>0.10) than HEC heifers. Heifers fed LE had higher (P<0.01) serum prolactin concentrations than HEA and HEC heifers, but not HEN heifers (P>0.10). Dietary inclusion of aspirin had no beneficial effect on body temperature and prolactin levels in heifers fed high-endophyte fescue forage, whereas inclusion of niacin tended to increase serum prolactin levels.

Expression of Russian Wheat Aphid (Homoptera: Aphididae) Resistance in Genotypes of Tall Fescue Harboring Different Isolates of Acremonium Endophyte

Experiments were conducted to compare the expression of Russian wheat aphid, Diuraphis noxia (Mordvilko), resistance in 2 genotypes of tall fescue grass, Festuca arundinacea Schreb., harboring different isolates of the endophytic fungus Acremonium coenophialum Morgan-Jones & Gams. Aphids did not select endophyte-free over endophyte-infected tiller sections in laboratory tests. In a laboratory population growth test, aphid numbers declined for 2 d on all endophyte-free plants and then increased. Aphid mortality was 100% on all infected plants after 4 d. Thus, antibiosis resistance to D. noxia was not specific to tall fescue genotype or to Acremonium isolate. In a field plot, numbers of Russian wheat aphids were significantly higher on endophyte-free tall fescue. Using these results, and results of other studies involving Acremonium -enhanced resistance to D. noxia in tall fescue and other host grasses, tile potential for using D. noxia to screen grass germplasm for Acremonium fungi is discussed.

Acremonium coenophialum‐Mediated Short‐ and Long‐Term Drought Acclimation in Tall Fescue

The mutualistic association between Acremonium coenophialum Morgan‐Jones and Gams and its tall fescue (Festuca arundinacea Shreb.) host provides plant scientists with unique opportunities to create superior turf and forage cultivars. The objectives of this research were to determine endophyte‐mediated drought acclimation in tissue‐cultured regenerants of tall fescue containing one of three A. coenophialum isolates during short‐ and long‐term drought stress. Two experiments were conducted by growing vegetative propagules of plants with endemic or introduced endophytes in 120‐L tubs containing fritted clay: one experiment examined water relations during a 15‐d drought period and the other during a 70‐d water stress period. Leaf water potential and turgor pressure responses to soil water content differed among infected and non‐infected plants, among endophytes inserted within a plant genotype, and among plant genotypes containing a common endophyte during 15 d of stress. Among endophytes, only EDN11 induced acclimation to 70 d of stress when inserted into plant genotype PDN2. Leaf water potential and turgor pressure were approximately 0.50–0.75 MPa greater when PDN2 was infected with EDN11 compared to other endophytes during the 70 d of stress. Endophyte had no effect on leaf osmotic potential and minimal effect on plant water soluble mineral and sugar concentrations, and endophyte‐mediated adaptation to drought stress was an avoidance mechanism. Because enhanced drought tolerance is a result of specific interactions between plant genotypes and endophyte isolates, selection of endophytes specifically for enhancing drought tolerance in tall fescue is not likely to have a general effect on the plant population.

Multiple families of peptide synthetase genes from ergopeptine-producing fungi

Several eukaryotic and prokaryotic micro-organisms produce small, biologically active peptides on multifunctional nonribosomal peptide synthetases. These peptide synthetases consist of series of similar peptide synthetase domains; each domain is hypothesized to perform reactions required for the incorporation of one of the constituent amino acids into the peptide. I investigated the peptide synthetase gene families of two plant-associated fungi, Acremonium coenophialum and Claviceps purpurea, that produce ergopeptine alkaloids. Ergopeptines are the products of a peptide synthetase, one of several peptide synthetases likely to be produced by these fungi. Degenerate oligonucleotides based on conserved amino acid residues in previously analysed peptide synthetases were used to prime the amplification of DNA from A. coenophialum and C. purpurea. Analyses of the deduced products of various clones showed that four different fragments of A. coenophialum DNA and three different fragments of C. purpurea DNA encoded peptide synthetase domains similar to those from other micro-organisms. Hybridization analyses indicated that the four fragments cloned from A. coenophialum represented three different peptide synthetase genes, most of which were present in multiple copies in the genome of this fungus. Each of the three clones from C. purpurea appears to be from a different peptide synthetase gene, only one of which is duplicated. One clone from A. coenophialum hybridizes with DNA from C. purpurea, making it a good candidate for involvement in ergopeptine production. The results of this study indicate that ergopeptine-producing fungi have multiple families of peptide synthetase genes. The data also demonstrate the feasibility of isolating fragments of peptide synthetase genes with a PCR-based approach.

Effects of environmental heat and intake of tall fescue seed infested with Acremonium coenophialum on the acid-base status of young bulls.

Effects of high environmental temperature and dietary intake of tall fescue (Festuca arundinacea) seed containing the endophyte Acremonium coenophialum on bovine acid-base status were studied using 3 groups of bull calves (2 Simmental, 1 Angus). Experimental animals were housed in controlled-climate chambers and subjected to gradual increases in environmental temperature, first while being fed an endophyte-free diet and then while being fed a diet containing 17% endophyte-infested fescue seed. Marked acid-base disturbances were not observed in any animals. In general, Pco2, HCO3-, base excess, and arterial blood pH values were reduced in response to heat stress, both with endophyte-free and endophyte-containing diets. In most individuals anion gap increased. These results reflected metabolic compensation for mild chronic alveolar hyperventilation and retention of organic acids. These findings suggest that, under conditions similar to those found during the summer in central Missouri, normal cattle should not be at great risk of developing respiratory alkalosis or other severe acid-base disturbances as a result of heat stress and/or intake of tall fescue endophyte.

Assessment of the mitogenic potential of the alkaloids produced by endophyte (Acremonium coenophialum)-infected tall fescue (Festuca arundinacea) on bovine vascular smooth muscle in vitro.

The objective of these experiments was to test the hypothesis that the major alkaloid classes found in endophyte-infected tall fescue could act as growth promoters for vascular smooth muscle. Bovine vascular smooth muscle cells (VSMC) from the dorsal metatarsal artery were grown in vitro and exposed to five concentrations (10(-6), 10(-8), 10(-9), 10(-11) and 0 M) of ergonovine, alpha-ergocryptine, ergovaline, and N-acetyl loline for 48 h. The mitogenic potential of the alkaloids was tested on both actively growing cells (serum fed, 10% fetal bovine serum) and quiescent cells (serum starved, 0.1% serum) to assess the need for serum constituents for alkaloid induced growth or toxicity. Ergonovine stimulated (P < .07) VSMC growth at 10(-6) M concentration in growing and quiescent culturs and at 10(-8) M concentration in quiescent cultures. alpha-Ergocryptine stimulated (P < .01) growth at 10(-6) M concentration in growing cultures and at 10(-8) and 10(-9) M concentrations in quiescent cultures. Ergovaline exhibited a dual activity on the growth of VSMC in culture, stimulating (P = .06) growth of quiescent cells at 10(-9) M concentration but inhibiting (P < .05) growth of growing cultures at concentrations of 10(-6) and 10(-9) M. This duality of activity was also noted for N-acetyl loline: N-acetyl loline stimulated (P < .05) growth of quiescent cultures at concentrations of 10(-8), 10(-9), and 10(-11) M but inhibited (P < .05) growth of growing cultures at concentrations of 10(-8) and 10(-9) M. The growth effects of the alkaloids in vitro on VSMC support in part the hypothesis that the alkaloids may contribute to the vascular complications noted in cattle grazing endophyte-infected tall fescue through hyperplasia of the intima. This would result in a decreased luminal diameter of the blood vessels and a resultant decrease in blood flow to the afflicted tissues. The diminished blood flow to tissues would result in tissue death and reduced ability to dissipate heat.

Supplemental protein and energy for beef cows consuming endophyte-infected tall fescue

Effects of energy and protein supplementation of endophyte (Acremonium coenophialum)-infected (E+) and noninfected (E-) tall fescue (Festuca arundinacea Schreb.) on forage intake, digestibility, N flow to the small intestine, and cow-calf productivity was evaluated in two experiments. In Exp. 1, 10 ruminally and duodenally cannulated steers were fed either E- or E+ hay with four supplements or E- or E+ hay unsupplemented. Four supplements formulated with either cracked corn or soybean hulls with 100 or 200 g/d of ruminally undegraded intake protein (UIP) were compared. Levels of UIP were varied by adding soybean meal or blood meal. Hay OM intake was not affected (P > .20) by source of energy of level of UIP; however, intake of E- was greater (P < .05) than that of E+. True ruminal OM digestion tended to be greater (P < .12) for steers fed 200 g/d of UIP than for steers fed 100 g/d. Steers receiving 200 g/d of UIP had increased (P < .10) total N flow to the duodenum compared with steers receiving 100 g/d but similar (P > .20) microbial efficiencies. In Exp. 2, 30 cows (average initial BW 459 +/- 26 kg) and their calves (average initial BW 74 +/- 5 kg and 74 +/- 5 d of age) grazed an 8.1-ha E+ pasture from late May to late July. Cows were individually fed supplements used in Exp. 1 each day. Cows that received cracked corn lost .10 kg/d when fed 100 g/d of UIP but gained .33 kg/d when fed 200 g/d. Cows fed soybean hulls and 100 g/d of UIP gained .07 kg/d, whereas cows provided 200 g/d lost .10 kg/d. Calves nursing cows supplemented with 100 g/d of UIP gained more (P < .08) BW because of increased (P < .07) milk consumption and slightly greater (P < .19) forage intake than calves nursing cows supplemented with 200 g/d of UIP.

Endophyte‐Free Tall Fescue Cultivars Grazed by Sheep: Forage Quality and Sward Characteristics

AbstractAlthough much work has focused on the performance of endophyteinfected (E+), Acremonium coenophialum Morgan‐Jones and Gams, tall fescue, Festuca arundinacea Schreb.; little information is available comparing performance attributes of endophyte‐free (E−) cultivars in the northeastern USA. Five paddocks of four cultivars [‘Festorina’, ‘Johnstone’, ‘Roa’, and ‘Kentucky 31’ (KY 31)] of E− tall fescue were rotationally stocked with ewes (Ovis aries) for 2 yr. Tall fescue and weed dry matter (DM) mass, leaf‐to‐stem ratio, and tiller density were determined both pre‐and post‐grazing and sward height was measured pro‐grazing. Forage crude protein (CP), acid‐detergent fiber (ADF), neutral‐detergent fiber (NDF), and in vitro dry matter disappearance (IVDMD) were determined by near infrared reflectance spectroscopy (NIRS). Total dry mass was higher for Festorina and KY 31 than for the other cultivars. Leaf‐to‐stem ratios were similar among cultivars. Forage height was greatest for Festorina and least for Johnstone. Fescue proportion of herbage biomass was greater and weed biomass lower for Festorina and KY 31 than for Roa and Johnstone. Tall fescue proportion of herbage biomass at the end of the trial was lowest for Johnstone. Mean tiller densities were similar for all cultivars and ranged from 2060 m−2 in spring to 1260 m−2 under stockpiling in fall. Pre‐grazed herbage CP of 204 g kg−1 was similar among cultivars. Roa tended to be low and Festorina high in both ADF and NDF, and IVDMD of Johnstone was higher than Festorina. Across seasons and years, ewe liveweight gain was higher for Johnstone than for the remaining cultivars, which were similar. Gains for Group 2 (late‐weaned) lambs were lower for KY 31 and were similar for the remaining cultivars. In light of this information, cultivar as well as endophyte status should be considered in designing experiments or planning grazing systems with tall fescue.

Endophyte infection effects on stomatal conductance, osmotic adjustment and drought recovery of tall fescue.

Presence of the endophytic; fungus Acremonium coenophialum Morgan-Jones and Gams in tall fescue (Festuca artuidinacea- Sehreb.) enhances host persistence in drought-prone environments. However, the physiological mechanism is not well understood. We investigated the influence of endophyte infection and water deficit on osmotic adjustment, stomatal conductance, tiller survival and leaf elongation rate of genotype GA87-122 and cv. Kentucky-31 (KY31) of tall fescue. Plants were grown in a greenhouse in pots containing fine-silty topsoil (experiment 1) or sand (experiment 2). In expt 1, endophyte-infected (EI) and endophyte-free (EF) isolines of GA87-122 were exposed to two drought preconditioning cycles, after which all pots were re-watered and osmotic adjustment determined. Osmotic adjustment was -0.46 and -0.51 MPa in El leaf blades and tiller bases and -0.29 and -0.13 MPa in EF leaf blades and tiller bases, respectively. In expt 2, EI and EF GA87-122 and KY31 Mere exposed to severe drought after two preconditioning cycles, then re-watered. During the second preconditioning drying cycle of KY31, stomatal conductance tended to be lower in EI than in EF plants, but the difference was significant (P⩽ 0-05) only at two sampling times. Shoot tissues osmotically adjusted 0.17-0.31 MPa more in EI than in EF plants. Tiller survival and leaf elongation rates were higher (P⩽ 0.05) in preconditioned EI than in EF plants. Basal-zone osmotic adjustment was correlated with tiller survival rate in GA87-122 and KY31 (r = 0.87, P⩽ 0.01 for both). Enhanced osmotic adjustment in the meristematic and growing zone might account far improved survival of tillers by facilitating protection of the apical meristem.

A study of the fungal endophyteAcremonium coenophialumin the roots of tall fescue seedlings

Tall fescue has formed a mutualistic relationship with the fungal endophyte Acremonium coenophialum. Endophyte-infected plants can have increased growth and survival when compared with endophyte-free plants. Responses to endophyte infection vary and may be host genotype and fungal biotype specific. The mechanism(s) by which endophyte infection confers increased growth and survival is not understood. This research determined the occurrence, distribution, and ultrastructure of endophyte hyphae in the roots of axenically grown tall fescue seedlings. Acremonium coenophialum was recovered from excised roots of endophyte-infected seedlings grown on diverse agar media and from sterile coarse sand. Successful recovery of the isolate varied with seedling age, root type, and growth medium. Overall, 67% of 218 endophyte-infected seedlings contained endophyte in their roots. Root-fungal ultrastructure of agar grown seedlings revealed epiphytic hyphae bearing conidiophores with typical conidia and an electron dense matrix that adhered hyphae to each other and to the root epidermal cell wall. Hyphae were found in regions previously occupied by root epidermal cells, but no direct penetration of intact cells was observed. Electron dense granules within the fungal cytoplasm contained high amounts of phosphorous relative to adjacent tissues. This may benefit endophyte-infected plants in low soil phosphate conditions.

Effects of Tall Fescue Endophyte Infestation on Relative Abundance of Small Mammals

AbstractSmall mammal populations were characterized nine times during six sampling periods on six plots in five different fields of tall fescue (Festuca arundinacea Schreb.) to determine differences in their abundance and species composition associated with the presence or absence of the endophytic fungus Acremonium coenophialum Morgan‐Jones &amp; Gams. No differences were found in species richness (n = 4 for both types) between endophyte‐free (E−) plots and endophyte‐infested (E+) plots. Capture success, number of individuals, total captures, and recapture rates were more for E− plots than for E+ plots. All four species [eastern harvest mice (Reithrodontomys humulis Giglioli), short‐tailed shrews (Blarina brevicauda Gray), pine voles (Microtus pinetorum McMurtrie), and cotton rats (Sigmodon hispidus Say &amp; Ord)] were captured more often in E− than in E+ plots. The diminished population densities of small mammals demonstrate the potential of E+ tall fescue as a permanent ground cover for waste disposal sites, orchards, tree farms, irrigation ditch banks, golf courses, and other residential, commercial, and industrial situations where burrowing activities of mammals may create human health hazards or financial burdens.

Toxic endophyte-infected tall fescue and range grasses: historic perspectives.

A historic profile of endophyte-induced tall fescue toxicosis is presented. A chronology of events is presented, beginning with the importance of finding Balansia-infected grasses in a tall fescue pasture in north central Georgia. This initial finding was followed by the discovery that another related endophyte was present in tall fescue and other major forage grasses. This species of endophyte was identified as Acremonium coenophialum. After this report was the important discovery that cattle performance was poor on Acremonium-infected tall fescue. Thus, this endophyte and its presence in tall fescue was implicated as the cause of tall fescue toxicosis and fescue foot. It was later established that this endophyte also produced ergot alkaloids. The related endophyte of perennial ryegrass, A. lolii, was subsequently shown to be responsible for the ryegrass staggers syndrome. Several other species of Acremonium have been associated with other important forage and turf grasses. Finally, important papers leading to the revelations that endophytic fungi and their grass hosts are ecologically significant and that most should be considered mutualistic symbioses are reviewed. Symbiotic grasses have enhanced physiological and morphological characteristics that offer biotechnological exploitations on one hand, but on the other solutions to the toxicity of tall fescue are difficult because grasses free of their fungal partner are generally ecological failures.

The effects of fescue toxicosis on beef cattle productivity.

Consumption of tall fescue forage infested with the endophytic fungus Acremonium coenophialum can result in a condition termed "fescue toxicosis," which is characterized by decreased weight gains, milk production, conception, and serum prolactin and an inability to dissipate body heat by beef cattle. These decreases in productivity have been estimated to cost beef producers more than $600 million annually. The unthrifty appearance of cattle consuming endophyte-infected tall fescue (E+) is most evident during periods of environmental heat or cold stress, suggesting an interaction with environmental conditions. Without temperature stress, cows consumed similar amounts of E+ and endophyte-free tall fescue (E-). But, when temperatures exceeded 32 degrees C, cows that grazed E+ consumed less forage than cows that grazed E-. After removal of E+ from the diet of steers, compensatory growth was observed, indicating no long-term negative effects of E+. A decrease in serum prolactin but apparently little change in other hormones has been measured after consumption of E+. Under periods of heat stress, animals had reduced ability to dissipate body heat, and blood flow to peripheral (rib skin), core-body (duodenum colon), and brain (cerebellum) tissues was decreased. Due to the depressive effects of E+ on prolactin and heat dissipation, dopamine antagonist therapy has been used in an attempt to rectify these changes. Dopamine antagonists have increased serum prolactin but there is limited evidence to suggest an improvement in heat dissipation. Experiments to elucidate the effects of E+ on alpha-1 and -2 adrenergic receptors may also offer insights into developing strategies to overcome the negative effects of E+ consumption. Preliminary results suggest that injections of an alpha-1 adrenergic antagonist (prazosin) in rats fed E+ under 32 degrees C conditions increased DM intake and reduced rectal temperature.

Response of Plant-Feeding, Predatory, and Soil-Inhabiting Invertebrates to Acremonium Endophyte and Nitrogen Fertilization in Tall Fescue Turf

The endophytic fungus Acremonium coenophialum Morgan-Jones & Gams conveys resistance to herbivory in tall fescue, Festuca arundinacea Schreber. In contrast, nitrogen fertilization generally enhances plant quality for herbivores. We studied the main effects and interaction of A. coenophialum and fertilization on plant-feeding, predatory, and soil-dwelling invertebrates in tall fescue turf. Fall armyworms, Spodoptera frugiperda (J. E. Smith), developed faster when reared on foliage from plots treated with medium or high rates of urea than on unfertilized tall fescue, but development rates were not affected by A. coenophialum. Greenbugs, Schizaphis graminum Rondani, preferred fertilized, endophyte-free fescue over nonfertilized, endophyte-free grass. Similarly, bird cherry-oat aphids, Rhopalosiphum padi (L.), developed fastest on fertilized, endophyte-free tall fescue. Fertilization, however, did not override the strong, adverse effects of A. coenophialum on both aphid species. In field plots, densities of leafhoppers, flea beetles, and Staphylinidae were generally higher in fertilized than in nonfertilized turf. Flea beetles and two of the five most abundant species of leafhoppers were less numerous in endophyte-infected plots. Predatory arthropods, earthworms, oribatid mites, and Japanese beetle grubs were equally abundant in endophyte-infected and endophyte-free plots. Fertilization did not affect the densities of oribatids or P. japonica, but earthworms were more abundant in fertilized plots on some dates. Results showed variable main effects, and an absence of interactive effects of A. coenophialum and fertilization on invertebrates in tall fescue. Fertilization of tall fescue probably will not nullify the benefits of endophyte-enhanced resistance

Tall Fescue Development in Response to Acremonium coenophialum and Soil Acidity

The fungal endophyte Acremonium coenophialum Morgan‐Jones &amp; W. Gams can modify productivity and stress tolerance of tall fescue (Festuca arundinacea Schreber). Clonal populations of five tall fescue genotypes were used in a glasshouse experiment to assess the effect of endophyte infection and soil pH on plant yield, demography, and development. Genotypes differed for most measured parameters, and a general lack of interactions among endophyte infection, genotype, and lime allowed use of treatment means to identify trends that may be reflected in larger populations. Infected plants had 13% greater shoot mass and 11% greater root mass than uninfected plants due primarily to increased tiller size. Larger size may increase tiller longevity and competitive ability. Endophyte did not affect relative tiller appearance rate as reduced relative leaf appearance rates were compensated by increased site usage. Liming of an acid soil (pH 4.3 for unamended soil) resulted in a 32% increase in dry matter production and increased root to shoot ratios of high‐yielding genotypes. Root to shoot ratio was affected by the interaction of lime and genotype; high‐yielding genotypes had greater root to shoot ratios when limed compared with nonlimed genotypes, while low‐yielding genotypes were not affected by liming. This increase was associated with greater site usage and tiller production; relative leaf appearance rate and tiller mass were unaffected. Endophyte modified the resource allocation patterns with resultant increase in phenotypic plasticity and potential competitive ability.