Acremonium Loliae Research Articles

Fungicide Effects on Acremonium Endophyte, Plant-Parasitic Nematodes, and Thatch in Kentucky Bluegrass and Perennial Ryegrass

Foliar applications of benomyl, chlorothalonil, iprodione, thiram, and triadimefon were assessed for possible nontarget effects on Acremonium loliae, plant-parasitic nematodes, thatch accumulation, and soil pH. Fungicides were applied monthly from April to September during 1983-1987 to field plots of Regal and Fiesta perennial ryegrass (Lolium perenne) and South Dakota, Merion, Sydsport, and Vantage Kentucky bluegrass (Poa pratensis). None of the fungicides significantly affected soil pH and only thiram enhanced thatch significantly when compared with untreated plots. Fungicides did not significantly affect population densities of plant-parasitic nematodes (...)

Comparisons of perennial ryegrass (Lolium perenne L.) accessions grown as turfs (lawns)

Accessions of Victorian perennial ryegrass (Lolium perenne L.) grown as turfs were inferior to or no better than European and North American ryegrasses developed specifically for turf. This applied to all aspects of their growth, except those of germination (which was faster, especially at temperatures around 12�C), thatch accumulation (which was less), and in their possession of an entophytic fungus, Acremonium loliae, which in the longer term could be associated with greater persistence. At the seedling stage, Victorian and turf ryegrasses produced similar dry weights, but the Victorian ryegrasses had fewer, larger leaves and tillers. Victorian ryegrass turf swards had lower tiller densities and standing dry weights, yet produced more clippings. The total production of Victorian ryegrass turfs was less than that of the turf ryegrasses. There were no differences in the seasonality of growth. In spring, flowering heads were more common in Victorian ryegrass turfs and the leaves of these turfs also shred more when mown. During the first year of turf growth, differential selection occurred in favour of plants that were prostrate, had shorter leaf sheaths, were later flowering, and that contained endophyte. The direction of selection confirmed the functional significance of observed differences between pasture and turf ryegrasses.

EVALUATION OF FOUR PERENNIAL RYEGRASS CULTIVARS IN NEW ZEALAND

Four perennial ryegrass (Lolium perenne) cultivars have been evaluated at a range of summer-autumn drought prone sites in New Zealand. Evaluation has been carried out at seven repllcated large plot grazing trials sown with clover and one trial without clover evaluated under mowing. The cultivars with a low level of lolium endophyte (Acremonium loliae) infection, Ruanui and the majority of Nui lines, have displayed poor persistence. In summer-autumn dry areas, sowing seed with a high endophyte content appears the only alternative to obtain a persistent perennial ryegrass pasture. Within the high endophyte cultivars (Yatsyn 1, Ellett and some Nui lines), Yatsyn 1 has performed consistently well in terms of long term yielding ability, indicating persistence. Keywords: Lolium perenne, endophyte (Acremonium loliae), annual yields, seasonal yields, Ruanui, Nui, Ellett, Yatsyn 1.

Productivity and persistence of cultivars and Algerian introductions of perennial ryegrass (Lolium perenne L.) in Victoria

We assessed the main Australian and New Zealand cultivars and a selection of Algerian introductions of perennial ryegrass at 3 sites in Victoria, 1 of which was irrigated. Seasonal yields of herbage, persistence and the presence of the ryegrass endophyte (Acremonium loliae) were assessed. At Drumborg (dryland), Ellett was the most productive cultivar over 3 years (9.25 t/ha DM total). At the other dryland site, Hamilton, the cumulative yields over 4 years were highest from the cultivars Kangaroo Valley Early (14.57 t/ha DM), Victorian (14.45 t/ha DM) and Ellett (13.80 t/ha DM); lesser yields were obtained from Grasslands Nui (12.92 t/ha DM) and Grasslands Ruanui (1 1.25 t/ha DM). At Numurkah, under irrigation. the yield of 4 cultivars, Ellett (22.14 t/ha DM total), Grasslands Nui, Kangaroo Valley Early and Victorian, were not different (P> 0.05) over 3 years. Differences between cultivars in patterns of growth were occasionally noted, particularly the higher rate of growth of Kangaroo Valley Early in winter. Under irrigation, Ellett and Grasslands Nui sometimes gave higher rates of growth than other cultivars during late spring and summer ( P < 0.05). Seed of 6 accessions from Algeria, which had been produced in Victoria from old plots, was sown for comparison with the commercial cultivars at Hamilton. The accessions grew poorly in the establishment year but later were as productive as the cultivars. Leaf sheaths were examined in year 4, for presence of the ryegrass en,dophyte (Acremonium loliae) in plants surviving the 1982-83 drought. Only plots of Ellett and Victorian contained high proportions of endophyte-infected plants (> 60% of plants infected). Relative to other entries, Ellett maintained a high plant density at all 3 sites. However, at 2 sites, Victorian and Grasslands Nui maintained a similar density to Ellett, and all the Algerian lines sown at Hamilton maintained a similar density to Ellett.

Paxilline biosynthesis by Acremonium loliae; a step towards defining the origin of lolitrem neurotoxins

Paxilline has been identified as a metabolite of the ryegrass endophyte Acremonium loliae in submerged culture and as a component, with lolitrem B, of the seed of endophyte-infected ryegrass. A role for paxilline as a biosynthetic precursor of lolitrem B is discussed.

Effect on theLoliumendophyte of nitrogen applied to perennial ryegrass seed crops

Abstract Three rates of nitrogen (N) fertiliser were applied at spikelet initiation to perennial ryegrass (Lolium perenne L.) seed crops. The treatments had no effect on the percentage infection of the endophyte, Acremonium loliae Latch, Christensen and Samuels, but the highest N rate significantly reduced the concentration of endophyte mycelium in harvested seed. Infected plants grown from seed harvested from these three treatments showed that reduced concentrations of endophyte in seed carried over into seedlings, mature plants, and seed harvested from these plants. The implications are discussed.

Viability ofLoliumendophyte fungus in seed stored at different moisture contents and temperatures

Abstract The effect of storage on viability of the Lolium endophyte fungus (Acremonium loliae Latch, Christensen and Samuels) in seed of perennial ryegrass was studied. Treatments included four initial seed moistures (13.8, 12.1, 10.0, and 8.6%); different storage bags (calico, polyethylene film (9, 35, or 70 μm thickness), and laminated aluminium foil-polyethylene); and four storage conditions (ambient 5–25°C, 5°C/70% RH; 0°C/30% RH; -15°C/90% RH). After 12 months of ambient temperature storage, seeds with final moisture contents > 11.3% had a rapid linear decline in endophyte viability from an initial 84% to < 15% at 13.0% seed moisture. Samples in 70 μm thick polyethylene and aluminium foil laminated packets had the highest endophyte viability (70–78%) at ambient temperatures. Seed stored at 5, 0, or -15°C had high endophyte viability with no effect of seed moisture. Seed germination was not affected by any treatments. Cool or low humidity environments ( < 60% RH) are required to maintain viability of ...

Isolation of feeding deterrents against argentine stem weevil from ryegrass infected with the endophyteAcremonium loliae

Infection of ryegrass (Lolium perenne) by an endophytic fungus (Acremonium loliae) confers resistance against the Argentine stem weevil (Listronotus bonariensis). Extracts from ryegrass clones, infected and uninfected with A. loliae, were compared in a feeding choice bioassay, and several fractions were identified which affected stem weevil feeding behavior. One stem weevil feeding deterrent, peramine C12H17N5O, has been isolated from infected ryegrass and partially characterized as a basic indole derivative. Extracts from culturedA. loliae had no effect on stem weevil feeding behavior nor was peramine detected in the fungal cultures examined. Peramine and the other active substances are hydrophilic in contrast to the lipophilic properties reported for the neurotoxic lolitrems also isolated from ryegrass infected with A. loliae and associated with causing ryegrass staggers disorder in livestock. It is suggested that ryegrass staggers and stem weevil feeding deterrency may arise by different biochemical mechanisms.

LOLIUM ENDOPHYTE AND SHEEP PERFORMANCE ON PERENNIAL RYEGRASS CULTIVARS

Some effects of lolium endophyte (Acremonium lolioe) on sheep production were evaluated using pure swards of high (SO%&gt;) and low (&lt; 5%) endophyte Nui and Ariki ryegrass. The proportion of infected tillers in high endophyte treatments increased by 19% in 15 months. Ryegrass staggers occurred on both high endophyte ryegrasses - being slightly worse on Nui. The peak ryegrass staggers outbreak did not coincide with peak endophyte mycelium concentration in ryegrass plants. Hoggets grazing the low endophyte ryegrasses had a 1.6 kg advantage in liveweight gain in spring, when allowances were equal, but fewer sheep grazing days. In summer and autumn sward damage by Argentine stem weevil, drought and over-grazing eliminated low endophyte Ariki treatments and reduced herbage production from low Nui to 70% of high endophyte Nui. Tiller densities in low endophyte treatments were 28% of those in high endophyte treatments. High endophyte Ariki had the highest overall production: 7.8 t/ha of herbage and 15 kg/head liveweight gain compared with 6.9 t/ha and 12.5 kg/head for high endophyte Nui and 4.7 t/ha and 9 kg/head for low endophyte Nui. Differences in production due to endophyte highlight the need for caution in interpreting results from trials when endophyte status of ryegrass is unknown. Keywords: Lolium endophyte, Acremonium loliae, ryegrass staggers, Lol~m perenne, live weight gain, pasture production, Ariki, Nui

Peramine, a novel insect feeding deterrent from ryegrass infected with the endophyte Acremonium loliae

Peramine, the major insect feeding deterrent isolated from perennial ryegrass infected with the endophytic fungus Acremonium loliae is assigned structure (1) based on spectroscopic evidence.

Perennial ryegrass seedling resistance to Argentine stem weevil

Abstract The presence of the Lolium endophyte fungus (Acremonium loliae Latch, Christensen and Samuels) in perennial ryegrass (Lolium perenne L.) seed confers resistance to adult Argentine stem weevil (Listronotus bonariensis Kuschel) feeding in seedlings. Seeds with non-viable endophyte develop into resistant seedlings, but become susceptible mature plants. Possibly this is caused by the translocation in the seedling of a remnant chemical, associated with endophyte in the seed, which is diluted or metabolised as the plant develops.

Isolation of feeding deterrents to Argentine stem weevil in cultures of endophytes of perennial ryegrass and tall fescue

Abstract Bioassays showed that a feeding deterrent to adult Argentine stem weevil (Listronotus bonariensis (Kuschel)) was produced in broth cultures of 4 strains of the endophyte Acremonium loliae (Latch, Christensen & Samuels) isolated from perennial ryegrass (Lolium perenne L.), and one strain of an endophyte isolated from tall fescue (Festuca arundinacea L.). Weevils could detect the deterrent when 0.05% w/w mycelium was incorporated in an agar-based diet, suggesting that it may be practical to maintain stem weevil resistance to ryegrass at low levels of endophyte infection per plant and thereby reduce the ryegrass staggersinducing component. Bioassays of chemical fractions have shown the deterrent to be very active, strongly hydrophilic, and present in both fungus mycelium and the supernatant broth. The behaviour of the active component suggests that it is a polar organic compound and possibly amphoteric in nature.

Endophytic fungi affect growth of perennial ryegrass

Abstract Clones of Lolium perenne L. ‘Grasslands Nui’ perennial ryegrass, either infected with or free from Acremonium loliae Latch, Christensen & Samuels, and clones of ‘Grasslands Ruanui’ perennial ryegrass, either infected with or free from a Gliocladium-like endophyte, were grown at 20°C for 8 weeks in a controlled-environment room. Nui plants infected with A. loliae yielded 38% more total dry matter than uninfected plants. Infected plants showed significant increases in total leaf area, tiller numbers, and growth of leaves, pseudo stems, and roots, but the shoot: root ratio was unaffected. Infection of Ruanui with the Gliocladium-like sp. had no significant effect on yield even though total leaf area was reduced by 19%. The benefits in yield and protection from damage by Argentine stem weevil from A. loliae-infected ryegrasses are discussed in relation to the known risk of ill-health in animals grazing infected pastures.