ABSTRACT

This chapter reviews knowledge of the effects of the Acremonium endophytes on host physiology, relating to growth and drought stress tolerance, and discusses approaches for using such endophytes to improve drought tolerance. Grasses have evolved various structural and physiological means of adapting to stress conditions, to ensure population stability in natural environments. Experiments with endophyte-infected and endophyte-free isogenic populations or clones in controlled environments separate plant physiological responses to the endophyte, from possible pest responses in field trials. Maintenance of high stand density due to the presence of the endophyte would promote the adaptability of tall fescue and perennial ryegrass for turf uses in stress-prone environments. Plant growth under controlled conditions is generally stimulated by the endophyte, especially with abundant nutrient availability, although individual genotypes vary greatly in this response. Greater survival of endophytic, over endophyte-free, tall fescue during severe drought occurs despite the complete loss of green leaf area and the cessation of growth of endophytic plants.