Summary1. Fungal endophyte -grass symbioses can have dramatic ecological effects, altering individual plant physiology, plant and animal community structure and function, and ecosystem processes such as litter decomposition and nutrient cycling. 2. Within the tall fescue (Schedonorus arundinaceus) -fungal endophyte (Neotyphodium coenophialum) symbiosis, fungal produced alkaloids are often invoked as the putative mechanism driving these ecological responses. Yet few measurements of alkaloids exist in the ecological literature. In this study, we quantified alkaloid levels in live, standing dead and decomposing endophyte-infected (E+) and -free (E)) plant material and simultaneously evaluated the direct and indirect effects of endophyte presence on tall fescue decomposition. 3. Loline and ergot alkaloid levels were consistently high in live E+ (common toxic strain of N. coenophialum) tall fescue biomass throughout the sampling period (May-November 2007), whereas, E) live and standing dead material had non-detectable alkaloid concentrations. Standing dead E+ biomass had significantly reduced alkaloid levels (6-19x lower than the levels measured in the corresponding live E+ biomass) that were equivalent to E) live and dead for loline but were still somewhat higher than E) material for ergots. 4. In an effort to test the role of alkaloids in directly inhibiting decomposition, as has been suggested by previous studies, we conducted a litter bag experiment using green, alkaloid-laden E+ and alkaloid-free E) tall fescue plant material. We incubated E+ and E) litter bags in both E+ and E) tall fescue stands for 170 days, and measured mass loss, carbon and nitrogen content, and ergot and loline alkaloid concentrations over the incubation period. 5. Consistent with previous reports, both direct and indirect effects of endophyte presence on litter decomposition were observed: endophyte presence in the litter and surrounding microenvironment significantly reduced decomposition rates. Surprisingly, despite large differences in alkaloid content between E+ and E) litter from Day 0-Day 21 of the incubation, direct effects of the endophyte on litter decomposition, while significant, were relatively small (differences in mass loss between E+ and E) litter were never >3%). Alkaloids were gone from E+ material by day 56. 6. We propose that results from this study indicating alkaloids are largely absent in standing dead material (the typical input to the decomposition process), and that despite being present in our litter bag experiment, failed to produce large differences in mass loss between E+ and E) material questions the supposition that fungal produced alkaloids directly inhibit decomposition. Additional studies exploring the mechanisms behind the direct and indirect effects of endophytes on this ecosystem process are needed.

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A 2-yr grazing experiment was conducted with crossbred steers (8 to 10 mo and with initial BW of 304 kg ± 34 kg in 2008 and 277 kg ± 24 in 2009) to evaluate animal performance and pasture responses of a late maturing tall fescue [Lolium arundinaceum (Schreb.) Darbysh; KYFA9301] population infected with the AR584 novel, non-toxic endophyte (Neotyphodium coenophialum; NE9301) as compared with Kentucky 31 fescue infected with the common toxic endophyte strain (KY31), 'Jesup' MaxQ fescue infected with the AR542 endophyte (MaxQ), and endophyte-free KYFA9301 (EF9301). Treatments were assigned for seeding in 1.0-ha pastures in a randomized complete block design with 3 replications. Pastures were grazed from 6 May to 23 July in 2008 (76 d) and 2 April to 25 June in 2009 (84 d). Each pasture was grazed with 4 tester steers and put-and-take steers were used to maintain forage mass at 2,500 ± 250 kg DM/ha. Shrunk BW was taken at initiation and termination of grazing each year. Rectal and skin temperatures were recorded, and jugular blood was collected each year at approximately d 28, 56, and study completion. Forage samples were collected at 2-wk intervals for analyzing CP, IVDMD, ADF, and NDF. Responses were analyzed with mixed models, and preplanned orthogonal contrasts were used to compare KY31 with non-toxic fescues, EF9301 vs. novel endophyte fescues, and NE9301 vs. MaxQ. All steer responses were similar (P > 0.10) among the non-toxic fescues. Average daily gains and total BW gain/ha for the 3 non-toxic fescues were greater (P < 0.001) than for KY31. Rectal/skin temperatures for the 3 non-toxic fescues were less (P < 0.001) and serum prolactin concentrations were greater (P < 0.01) than for KY-31. Pasture carrying capacity was greater (P = 0.003) for KY31 than the 3 non-toxic fescues and was greater for EF9301 (P = 0.017) than the 2 novel endophyte fescues. However, stocking rates (kg BW/ha) at the initial and midpoint days of grazing were similar (P > 0.40) among endophyte-fescue combinations, but by the end of the grazing season, stocking rate was greater (P < 0.001) for KY31 than for the non-toxic fescues and was greater (P = 0.053) for NE9301 than for MaxQ. Results indicated that NE9301 is as effective as EF9301 and MaxQ in improving BW gain and alleviating fescue toxicosis and that NE9301 can provide greater carrying capacities than MaxQ in late June and July.

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Tall fescue (Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.) can form a symbiosis with the fungal endophyte Epichloë coenophiala, whose presence often benefits the plant, depending on plant and fungal genetics and the prevailing environmental conditions. Despite this symbiosis having agricultural, economic, and ecological importance, relatively little is known regarding its response to predicted global climate change. We quantified the ecophysiological responses of four tall fescue genetic clone pairs, where each pair consisted of one endophyte‐infected (E+) and one endophyte‐free clone, to climate change factors of annually elevated temperature and seasonally increased precipitation. Endophyte presence increased fescue tillering and biomass production in the elevated temperature treatment and greatly enhanced the ability of two of the fescue clones to recover from the hot and unusually dry summer. Surprisingly, endophyte infection also stimulated biomass production and photosynthesis rates (for one clone) in the most mesic treatment (additional precipitation). Toxic ergot alkaloid concentrations increased in E+ individuals exposed to elevated temperatures, particularly in the fall, but the strength of the response varied across E+ genotypes. Overall, this study suggests that choice of plant and endophyte genetic material will be important in determining the productivity, toxicity, and resilience of tall fescue pastures under future climate conditions.