Endophytes and Turfgrass Performance
by Dr D.E. Aldous

What are endophytes?

The grass endophytes are a group of fungi in the Balansiae tribe of the Clavicipitaceae (Ascomycetes) family, which systematically infect grass, and with the exception of Epichloe typhina, do not emerge from the plant (Clay, 1990). They are closely related to the ergot fungi (Claviceps spp.) and include the choke fungus E. typhina (name of the sexual stage; the name of the asexual stage is Neotyphodium typhinum). The sexual method of reproduction has not been observed in most of the turfgrass endophytes, hence they are named by their asexual genus name, Neotyphodium.

Why are endophytes important in turfgrass management?

A trend developing in Australia and overseas is towards minimal use of chemicals through integrated pest management and the use of biological controls for pests and diseases. It has been found that the presence of fungal endophyte in turfgrass, while not a panacea, not only helps fulfil the goals of lowering chemical inputs in turf, but also improves photosynthetic rate (Marks and Clay, 1996), deters insect and mammal herbivory (Fraser and Breen, 1994; Sun and Brede, 1997), increases fungal disease resistance, and water stress tolerance (White et al., 1992), and improves the utilization of nitrogen, and plant persistence (Richardson and Bacon, 1993). A recent review of the endophytes in turf grasses by Mebalds and Aldous (1994) have shown that the benefits accruing to turfgrasses include enhanced resistance to insect attack, increased resistance to nematode attack, enhanced establishment and growth in turfgrass, improvements in drought tolerance and nitrogen utilization, and higher quality scores over endophyte-free grasses in terms of turf quality and colour ratings. All these benefits can be achieved with fewer chemical inputs and lower maintenance costs in maintaining the turfgrass system.

Can I see endophytes?

Endophytes cannot be seen with the naked eye. Because of their size they can only be seen under a microscope under high magnification.

Where are endophytes found?

Some 80 genera and hundreds of grass species are known to be hosts for fungal endophytes (Clay, 1990). Most have been found in grasses in the Tribe Pooidea, predominantly the temperate grasses, among which most turf species are found. Different species of endophyte infect different grass species. Thus perennial ryegrass (Lolium perenne) is infected by N. lolii, tall fescue (Festuca arundinacea) by N. coenophialum, chewings fescue (F. rubra subsp. commutata), strong creeping red fescue (F. rubra subsp. rubra), slender creeping red fescue (F. rubra subsp. litoralis), blue fescue (F. glauca), hard fescue (F. longifolia), creeping bent (Agrostis stolonifera) and browntop bent (A. tenuis) by N. typhina and meadow fescue (F. pratensis) by N. uncinatum (Sun et al. 1993; Christensen et al. 1993).

Neotyphodium typhinum has been recorded on wild populations of Agrostis spp. in the USA and the UK, but not found in turf type bentgrasses in Australia. Work carried out by Aldous, Mebalds and Blaze (1994, 1995) and Aldous and Mebalds (1995) on commercially available turf type bentgrass cultivars and naturalized bentgrasses collected from golf courses around Victoria, indicated that there are no naturally occurring endophytes in bentgrasses in Australia or that they are rare. This has since been confirmed on the plants or seeds of a number of creeping bentgrass (Agrostis stolonifera) ecotypes (Sun and Brede, 1997) in the United States. Results also suggest that there are no naturally occurring Neotyphodium spp. endophytes found in the native grass genera of Danthonia, Poa, Microlaena, Chloris and Bothriochloa spp. in Victoria, or again that they are rare (Aldous, Isaacs and Mebalds, 1999).

How are endophytes spread?

In nature, Neotyphodium spp. endophytes (with the exception of N. typhinum) do not spread by infecting neighbouring plants but can only be passed on maternally through the seed of infected plants. Unlike mycorrhizal fungi, these endophytes only occur in above-ground plant tissues such as the crown or leaf of the turf grass plant. Endophytes of the genus Balansia occur in warm-season grasses, and at present, are restricted to the American continent (White, 1987).

How can you test for endophytes?

This is best be done through a laboratory. Seeds are surface sterilized by soaking them in 50% v/v sulphuric acid for 30 minutes. They are then rinsed in sterile water for 30 minutes then soaked in undiluted sodium hypochlorite (12.5% available chlorine) for 30 minutes and rinsed again in sterile water. The seed is then embedded into potato dextrose agar (PDA) (Latch and Christensen, 1985). The inoculated plates are then sealed with Nesofilm and incubated for 2-3 weeks at room temperature (20°C). The plates need to be examined for the presence of endophyte colonies by a trained technican.

Is endophyte enhanced seed available in Australia?

Plant breeders now recognize the benefits of endophyte in turfgrass and have incorporated them into known grass varieties. Many endophyte enhanced fine and tall fescues and perennial ryegrass cultivars are available in Australia. When sowing endophyte rich seed adhere to the requirements stated on the packet.

About the Writer:
Dr David Aldous is Principal Lecturer, within the Department of Resource Management & Horticulture, Institute of Land and Food Resources, The University of Melbourne, and has teaching, research and outreach interests in environmental horticulture.

Contact Dr Aldous at:
Department of Resource Management & Horticulture,
Institute of Land & Food Resources,
The University of Melbourne-Burnley Campus
Swan Street, Richmond, 3121, Victoria, Australia

Further Reading

Aldous, D.E., S. Isaacs, and M. I. Mebalds (1999). Endophytes in the genus Neotyphodium are not found in Australian native grasses. Australian Plant Pathology Journal, Volume 28, (in press).

Aldous, D.E., M. I. Mebalds, and K.Blaze’ (1995). Endophytes in turfgrass. Final Research Report to the Horticultural Research and Development Corporation. Victorian College of Agriculture and Horticulture, Burnley and Institute for Horticultural Development, Agriculture Victoria, Knoxfield. Project TU304. 40pp.

Aldous, D.E. and M.I. Mebalds (1995). Evaluation of endophyte in creeping bentgrass (Agrostis stolonifera) and common bentgrass (A. capillaris). Proceedings of the 2nd ATRI Turf Research Conference. Volume 2:49-60.

Aldous, D.E., M.I. Mebalds, and K. Blaze’. (1994). Endophytes in creeping bentgrass (Agrostis stolonifera) and (A. palustris). Journal of the Royal Australian Institute of Parks, December, pp, 29-30.

Clay, K. (1990) Fungal endophytes of grasses. Annual Review of Ecology and Systematics 21:275-297.

Fraser, M.L. and Breen, J.P. (1994) The role of endophytes in integrated pest management for turf. In Handbook of Integrated Pest Management. Ed A.R. Leslie. Lewis Publishers. Boca Raton, Florida. pp 521-528.

Glenn, A.E. C.W. Bacon, R.Price, and R.T. Hanlin (1996). Molecular phylogeny of Acremonium and its taxonomic implications. Mycologia 88:369-383.

Latch, G.C.M. and Christensen, M.J. (1985). Artificial infection of grasses with endophyte. Annals of Applied Biology 107: 17-24.

Marks. S. and K. Clay (1996). Physiological responses of Festuca arundinacea to fungal endophyte infection. New Phytol. 133, 727-733

Mebalds, M.I. and Aldous, D.E. (1994). Endophytes in turfgrass. In Proceedings of trends in sports turf and amenity grasslands, (Eds). Aldous, D.E. and Arthur, T., Royal Australian Institute of Parks and Recreation, VCAH, Burnley, Melbourne, Sept. pp. 30-42.

Richardson, M.D. and Bacon, C.W. (1994) Stress tolerance of endophyte-infected turfgrass. In Handbook of Integrated Pest Management. Ed A.R. Leslie. Lewis Publishers. Boca Raton, Florida. pp 529-537.

Sun, S., Clarke, B.B., Huff, D.R., Betts, L.L., Smith, D.A. and White, J.F. Jr. (1993) Enhanced performance and new sources of Acremonium typhinum in fine fescues. Proceedings of the 2nd International Symposium on Acremonium/Grass Interactions. Eds D.E. Hume, G.C.M.Latch and H.S.Easton Feb. 1993. Palmerston North N.Z. pp 23-26.

White, J.F. and Baldwin, N.A. (1992). A preliminary enumeration of grass endophytes in west central England. Sydowia 44: 78-84.

White, J.F. (1993) Endophyte-host associations in grasses. XIX. A systematic study of some sympatric species of Epichloë in England. Mycologia 85: 444-455.

White, J.F., Glenn, A.E. and Chandler, K.F. (1993) Endophyte-host associations in grasses. XVIII. Moisture relations and insect herbivory of the emergent stroma leaf of Epichloë. Mycologia 85: 195-202.

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