PHYSIOLOGICAL INTERACTIONS OF ENDOPHYTIC FUNGI AND THEIR HOSTS - BIOTIC STRESS TOLERANCE IMPARTED TO GRASSES BY ENDOPHYTES

The association of an endophyte and its host grass is mutualistic. Inf ected plants are protected from attack by some species of insects, nem atodes and fungi and they may be less attractive to grazing animals be cause of the toxicity they impart to the grass. The endophyte is provi ded with nutrients and is transmitted in the seed. Recent research has revealed that within a single species of endophyte there are strains which differ in their ability to produce particular compounds in the p lant. Thus, some strains of endophyte which confer plant resistance to particular biotic stresses, such as resistance to insects, do not pro duce compounds toxic to grazing animals. Such strains are of particula r benefit to pastoral farmers as they can be selected and used to infe ct other grasses. Biological control of predators and parasites of gra sses through the use of selected endophyte strains is timely as chemic al control of pests and diseases becomes increasingly restricted. This paper reviews the diverse examples of biotic stress tolerance which e ndophytes confer to grasses and suggests lines of research which it ma y be profitable to pursue.