G. C. M. Latch

Fungal endophyte-infected grasses: Alkaloid accumulation and aphid response.

The occurrence of the alkaloidsN-formyl andN-acetyl loline, peramine, lolitrem B, and ergovaline and the response of aphids to plants containing these compounds were determined in species and cultivars ofFestuca,Lolium, and other grass genera infected with fungal endophytes (Acremonium spp., andEpichloe typhina). Twenty-nine of 34 host-fungus associations produced one or more of the alkaloids, most frequently peramine or ergovaline. Three alkaloids (lolines, peramine, and ergovaline) were found in tall fescue and in perennial ryegrass infected withA. coenophialum, while peramine, lolitrem B, and ergovaline were present in perennial ryegrass and in tall fescue infected withA. lolii and inF. longifolia infected withE. typhina. WhileA. coenophialum andA. lolii produced similar patterns of alkaloids regardless of the species or cultivar of grass they infected, isolates ofE. typhina produced either no alkaloids or only one or two different alkaloids in the grasses tested. Aphid bioassays indicated thatRhopalosiphum padi andSchizaphis graminum did not survive on grasses containing loline alkaloids and thatS. graminum did not survive on peramine-containing grasses. Ergovaline-containing grasses did not affect either aphid.

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.

Ryegrass endophyte, incidence, and control

Abstract There was a high incidence of a fungus endophyte in most of the perennial ryegrass pastures and seed lines examined. The fungus was still viable in seed which had been stored at 0–5°C for 7 years. The main means of endophyte dissemination appear to be the sowing of infected seed and the re-seeding of infected plants in pastures. Field observations showed that when endophyte-free seed was sown, a set of mown plots and a grazed pasture were still free of endophyte 4 years after establishment. Endophyte-free seedlings were obtained by treating infected seeds with the fungicides propiconazole or prochloraz at 0.5 g/kg of seed. The fungus was eradicated from infected plants growing in pots by drenching the soil with a suspension of benomyl at 0.1 g per litre of growing medium.

Influence of Acremonium endophytes on perennial grass improvement

Abstract Acremonium endophytes affect their host grasses in various ways. Many of these effects are desirable such as protecting grasses from attack by some insects, nematodes, and plant diseases. Endophytes also make their hosts more tolerant of drought and some plants have enhanced growth and tillering. However, there are aspects of endophytes which are undesirable in that infected grasses can produce alkaloids which, when present at sufficiently high levels, affect the health and production of grazing animals. Thus the benefit of having endophytes in Australasian pastures is debatable. This paper reviews current knowledge on endophytes and concludes that infecting grasses with strains of endophytes which do not produce the alkaloids harmful to animals may overcome the undesirable aspects of endophytes.

Effect of Growth Conditions on Alkaloid Concentrations in Perennial Ryegrass Naturally Infected with Endophyte

A preliminary study of the effect of water stress on alkaloid concentrations in endophyte-infected perennial ryegrass (Lolium perenne) focused on artificial infections with selected endophyte strains (Barker et al., 1993). This paper reports the results of studies of the impact of environmental factors (nitrogen, water, temperature) on the concentration of alkaloids in “Nui” perennial ryegrass naturally infected with Neotyphodium lolii, a more typical component of New Zealand pastoral forage.

Purification and characterisation of the antigens of endophytic fungi isolated from Lolium perenne and Festuca arundinacea in New Zealand

Abstract Enzyme-linked immunosorbent assay (ELISA) based on immunoglobulins produced against Acremonium loliae mycelium has been shown to specifically detect the Acremonium species endophytes of both Lolium perenne and Festuca arundinacea. The major antigen is the polysaccharide moiety of a high molecular weight protein lipopolysaccharide complex which can be purified from culture filtrates. The polyacrylamide gel electrophoretic protein profiles of the soluble antigens from different grass endophytes are distinctive and have been used to differentiate endophyte isolates which are serologically indistinguishable.

Occurrence of Extreme Alkaloid Levels in Endophyte-Infected Perennial Ryegrass, Tall Fescue, and Meadow Fescue

In the course of measurements of alkaloid concentrations in several thousand samples of endophyte-infected perennial ryegrass, tall fescue, and meadow fescue plants for diverse studies, we have encountered a number of samples with alkaloid concentrations which greatly exceed the highest levels reported in previous studies (e.g. Welty et al., 1994).