|White, Jr., J|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/1997
Publication Date: N/A
Interpretive Summary: Scientists at RRC established in 1977 that there was a fungus that lived within the above ground portion of a pasture grass known as tall fescue, and it was this fungus that was responsible for toxicity to livestock. The fungus is referred to as an endophyte, and endophytes are found in most grasses, particularly those used for turf and conservation purposes. Our continued work and that of others have established that this fungus-grass combination is normal and essential in order for grasses to survive the many ecological pressures such as grazing, insect and nematode infestations, fungal disease, drought, competition, and a lack of soil nitrogen. Thus, the rational for using endophyte-infected grasses for turf. The topic of this manuscript was requested by the editor of the journal CROP SCIENCE, Agronomy Society, as a feature article for the Review and Interpretation Section. We have since renamed the many species of endopytes Neotyphodium Glenn, Bacon, and Hanlin using molecular techniques. Grasses infected with these fungi are excellent choices for turfgrasses. However, the endophytes must be modified by molecular techniques since they do not reproduce. This manuscript reviews the basic biology of endophytes, specific endophyte-enhanced traits used for turfgrasses, and the means which the fungi use to become genetically modified in the absence of sex. The current laboratory techniques used to modify and maintain endophytes in various turfgrasses for increased performance, the problems associated with molecular techniques, and the problems associated with using endophyte-enhanced turfgrasses are also discussed.
Technical Abstract: Over the past decade, the signficance of symbiotic fungal endophytes in turfgrasses was established as having the potential for supplementing the genetics of turfgrass improvement since endophyte-infected grasses frequently show enhanced performance. Endophyte-enhanced traits include insect and mammalian deterrence to herbivory, and often increased tolerance to drought and other abiotic stresses. The endophytes that are of the major focus for current use include species of Neotyphodium (=Acremonium) e.g. N. coenophialum, N. lolii, and other species of Neotyphodium. These endophytes can be removed from their host, transformed by molecular technology, and reinserted into grasses. However, these fungi have other means for genetic variation, which might include chromosome polymorphisms, altered chromosome structures, and loss of nonessential chromosomes. Thus, the genetics related to an endophyte-enhanced trait of that turfgrass might not be stable. However, the potential for genetic engineering of the endophytes is growing nearer with recent application of DNA mediated techniques. Furthermore, genetic engineering or other approaches may soon lead to endophyte-grass associations that have further enhanced fitness or are more benign to wildlife. Before such genetically modified systems are marketed, particular attention and extensive field tests should be applied to ensure that they retain their beneficial characteristics and have truly acquired their intended improvements.