Lolium Endophyte Research Articles

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.

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 ...

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

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.

Fungal endophytes of grasses and their effects on an insect herbivore.

The effects of endophytic fungi (Tribe Balansiae, Clavicipitaceae, Ascomycetes) of grasses on an insect herbivore were studied by feeding paired groups of larvae of the fall armyworm (Spodoptera frugiperda, Noctuidae, Lepidoptera) leaves from either infected or uninfected individuals. Perennial ryegrass infected by "the Lolium endophyte", tall fescue infected by Epichloe typhina, dallisgrass infected by Myriogenospora atramentosa, Texas wintergrass infected by Atkinsonella hypoxylon, and sandbur infected by Balansia obtecta were utilized. The endophytes of ryegrass and fescue previously have been shown to be toxic to mammalian herbivores and to deter feeding of some insect herbivores. In this study we extend the antiherbivore properties of those endophytes to the fall armyworm and demonstrate that fungal endophytes in three other genera have similar antiherbivore properties. For most grasses, survival and weights of fall armyworm larvae fed infected leaves were significantly lower and larval duration was significantly longer compared to larvae fed uninfected leaves. Resistance to herbivores may provide a selective advantage to endophyte-infected grasses in natural populations.

Effect ofLoliumendophyte fungus infections on behaviour of adult Argentine stem weevil

Abstract The effect of Lolium endophyte on feeding and oviposition by adult Argentine stem weevil (Listionotus bonariensis( (Kuschel)) was studied in the laboratory and screenhouse. The effects of endophyte on weevil behaviour were determined in choice and non-choice experiments. Feeding and oviposition were reduced in weevils confined on endophyte-infected plants compared to those confined on endophyte-free plants.

The Lolium endophyte: return from anonymity

The commensal, above ground fungus in ryegrass, known simply as the Lolium endophyte, which has been well studied in the past (McLennan, 1920; Sampson, 1935, 1937; Neil, 1940, 1941; Lloyd, 1959) has recently emerged as the bright new hope in the ryegrass stagger aetiology research. Fletcher and Harvey (1981) showed a highly significant correlation between the amount of infection in three ryegrass cultivars and the observed intensity of ryegrass staggers in a split plot randomised grazing trial at Lincoln. At the same time, a new group of neurotoxins, the lolitrems, were also being linked with ryegrass staggers by Gallagher et. al (1981). It would appear that an association between the endophyte and the host trigger the production of these lolitrems, but whether they are produced by the host in response to invasion of the intercellular space by the fungus (as is the case in the production of phytoalexins) or by the fungus itself in response to specific apoplastic nutrients supplied by the host, has not been fully established. Ironically, the Lolium endophyte was suggested the possible aetiological agent in ryegrass staggers several years ago. It was rejected, however, on three counts: Firstly, when axenic cultures of the fungus (grown on ryecorn seed) were fed to sparrows and mice, no ill effects were noted (Cunningham, 1958). Secondly, when endophyte-infected seed was fed to a range of animals, including one sheep, no toxicity was noted (Neil, 1941); and thirdly, it was considered by Neil in 1940 that "a widely distributed fungus such as Lo//urn endophyte could not be responsible for localised outbreaks of ryegrass staggers!' (Cunningham &amp; Hartley, 1959). The Lincoln group of researchers have used two approaches to determine why these three factors caused such a rejection. Firstly, an ultrastructural study was carried out at Canterbury University on the interaction between the fungus and the host, and the nature of the fungus in seed and in pure culture (Fineran et al, in prep.; Gallagher et al. 1982). Secondly, a study of endophyte levels in some South Island pastures where outbreaks of ryegrass staggers had occurred was carried out (Harvey, 1982).

LOLIUM ENDOPHYTE LEVELS IN COMMERCIAL PERENNIAL RYEGRASS SEED LINES

A survey of perennial ryegrass seed lines received for testing in 1982 revealed different Lolium endophyte infection level characteristics for different cultivars. Grasslands Ruanui had low infection levels, Ellett had high and Grasslands Nui and other perennial ryegrass samples had variable infection levels. Differences in infection levels are ascribed to the infection status of the original cultivar material and the storage period between harvest and sowing during the seed multiplication process. The problems associated with providing a seed testing service for Lolium endophyte are also discussed.

RYEGRASS STAGGERS: CLINICAL, PATHOLOGICAL AND AETIOLOGICAL ASPECTS

This paper briefly introduces animal disease aspects of ryegrass staggers IFiGS) and describes the occurence and the clinical signs of the disease. Recent suggestions for the production of a reversible biochemical lesion in the central nervous system are mentioned in relation to the apparent lack of specific morphological lesions found in sheep. The recent isolation of novel potent neurotoxins, the lolitrems, from toxic pasture material is reviewed. There is now strong circumstantial evidence that the lolitrems produce the neurotoxic disease of RGS and also that the lolitrems are elaborated in the close association of perennial ryegrass with its parasitic fungus, Lolium endophyte, in pastures. Under what conditions the lolitrems are produced, or their precise locus within the association, are not yet known.

A COMPARISON OF PERENNIAL GRASSES UNDER SHEEP GRAZING ON THE CENTRAL PLATEAU

Details are given on the production and survival over four years of five perennial grasses under rotational sheep-grazing on a pumice soil. The comparison involved three perennial ryegrasses ('Grasslands Nui and Ruanui', and Yates Ellett), and mixtures of Ellett with 'Grasslands Roa' tall fescue and Ellett with 'Grasslands Maru' phalaris. All pastures were sown with white and red clovers. Annual dry matter yields from Nui and Ellett pastures were similar, at about 6,500 kg/ha. Ruanui pastures were on average 600 kg/ha lower. The pastures containing tall fescue and phalaris were similar to Ellett. The major seasonal yield effects were in autumn and winter, when Ruanui pastures were substantially poorer than those with Nui and Ellett. Ryegrass yield of Ellett pasture was greater than Nui, and Nui was greater than Ruanui at all seasons. Ellett ryagrass was a higher proportion of the total yield at all times, and had higher tiller populations than Nui and Ruanui. Neither tall fescue or phalaris were, able to compete with Ellett ryegrass. It is suggested that neither of these be sown with ryegrass. Clover yields were higher in Ruanui than Ellett pastures, with Nui intermediate. The use of Nui, Ellett and Ruanui ryegrasses is related to the problems of seasonal distribution and total annual yields of pastures on the Central Plateau. It is suggested using Nui or Ellett as the base for perennial pastures will give substantial increases in production. Ellett ryegrass had higher survival than Nui which was considered an advantage, though this was achieved at the expense of a small reduction in clover vields. Keywords: Perennial ryegrass, Ellett, Nui, Ruanui, Roa tall fescue, Maru phalaris, canary grass, sheep grazing, central North Island, Central Plateau, grass grub, Argentine stem weevil, Lolium endophyte.

RYEGRASS STAGGERS: FURTHER SUBSTANTIATION OF A LOLIUM ENDOPHYTE AETIOLOGY AND THE DISCOVERY OF WEEVIL RESISTANCE OF RYEGRASS PASTURES INFECTED WITH LOLIUM ENDOPHYTE

An experiment was planned and undertaken to obtain further evidence on the association of the Lolium endophyte (a fungus parasitic in some perennial ryegrass) with the occurrence of ryegrass staggers in sheep (Fletcher &amp; Harvey, 1981). In the experiment, 39 sheep grazing four plots established with perennial ryegrass seed (Lolium perenne) highly (&gt;90%) infected with the endophyte all developed clinical ryegrass staggers over a 26 day grazing period. The same number of sheep grazing plots established from seed found to have negligible (

EFFECTS OF PRESENCE OF LOLIUM ENDOPHYTE ON GROWTH RATES OF WEANED LAMBS, GROWING ON TO HOGGETS, ON VARIOUS RYEGRASSES

Weaned lambs when growing to hoggets on old pasture acotype ryegrass, had shown significantly lower weight gains immediately prior to clinical signs of FIGS, than those on Ruanui ryegrass pasture. The difference was not correlated to quantity of harbaga on offer. Enzyme linked immunosorbent assay of plant tissue showed higher concentration of Lolium endophyte in that period than prior to subsequent periods. Keywords: ryegrass staggers, Lolium andophyte, live weight

Effects of several fungicides on theLoliumendophyte in ryegrass plants, seeds, and in culture

Abstract A range of fungicides, mostly systemic and many in the ergosterol-biosynthesis inhibiting group, was tested against the Lolium endophyte. Fungicides were sprayed on infected plants or applied as seed treatments to infected seed, and were also tested for their ability to inhibit growth of the fungus in culture at concentrations of 2.5–5000 ppm. The endophyte was resistant to many of the fungicides tested, and only propiconazole (‘Tilt’) reduced the level of endophyte after foliar application. In culture, the fungus was most sensitive to prochloraz (‘Sportak’), but showed some sensitivity to propiconazole and imazalil (‘Fungaflor’). Prochloraz completely controlled the fungus in seed, and propiconazole gave good, but not complete, control. Both chemicals produced some phytotoxic effects. No control was obtained with seed treatments of triadimenol + fuberidizol (‘Bay tan FI7’) or carboxin + thiram (‘Vitaflo 200’).

The presence and absence of an endophytic fungus in Lolium temulentum and L. perenne

Summary The study of a series of pedigree populations of single plants of L. temulentum and L. perenne extending through six seasons has shown that both species can exist either with or without an endophytic fungus. This fungus, when it occurs, invades the leaves, stems and tiller buds, and in a perennial plant it is distributed by vegetative propagation. It does not appear to invade the roots and it is in my opinion distinct from the Phycomycete type which has been recorded in these and other grasses, and in plants not closely related. The Lolium endophyte invades the ovule, and that it is mechanically inherited from the female parent only has been shown by the reciprocal crossing of free and infected plants. While races free from infection may arise from infected individuals, the origin of the infected races themselves is still obscure. The problems of chief interest, namely, the identity of the organism and the biological aspects of its connection with the grasses, still await solution. That the relation is not an obligate one so far as the higher plant is concerned emerges from the experimental work discussed in this paper.