Grasses and Neotyphodium endophytes:: co-adaptation and adaptive breeding

Neotyphodium endophytes profoundly affect the biology of their host grasses, including the important forage species perennial ryegrass, tall fescue and meadow fescue. The endophytic association is finely balanced, involving adaptation in each associate. The evidence for co-adaptation is discussed. The presence of endophyte, and the difference between endophyte strains, can affect some plant properties more than genetic variation intrinsic to the host. Conversely, host genotype exerts significant influence on the activity of the endophyte. Control of endophyte status is essential in any grass breeding programme, and developing knowledge of endophyte and its role in a herbage association offers new opportunities to grass breeders.