The Endophytic Niche and Grass Defense

Authors: Bacon, Charles; Hinton, Dorothy; Glenn, Anthony - Tony

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 3/1/2008
Publication Date: 7/1/2009
Citation: Bacon, C.W., Hinton, D.M., Glenn, A.E. 2009. The Endophytic Niche and Grass Defense. In: White, J.F. and Torres, M., editors. Defensive mutualism in microbial symbiosis. Boca Raton, FL:Taylor & Francis Group, LLC. p. 383-404.

Interpretive Summary: Much research has been done on the interactive nature of the tall fescue grass and its fungal partner. This research has established that this very valuable forage, turf and conservation grass, which occupies 30 million plus acres in the south-eastern USA, is toxic to most livestock and wild animals. It is further established that this grass is toxic due to the fungus that resides within the plant as an endophyte, which form what is referred to as a symbiotic association. This symbiotic association is further distinguished as being beneficial since the fungus provides the necessary toxins, growth factors, and drought defences necessary for persistence under grazing pressures. What is not known is how environmental stimuli are perceived and communicated to each of the partners within this symbiotic association to adverse conditions. We were invited to review the manner of communication between the fungus and the grass. We review the developmental and morphological nature of the niche that house the fungus as an endophyte and describe the positive benefits derived from the association. We also review information on the nature of signalling between the fungus metabolism and the grass metabolism and the work that has led to how these signals operate to effects a response to environmental changes. Additional information is discussed in terms of how these signals crosstalk to amplify any necessary metabolites to overcome stresses. Thus signalling and crosstalk provide the necessary communication between these two distinctly different organisms for ecological success.

Technical Abstract: Much research has been done on the interactive nature of the tall fescue grass and its fungal partner. This research has established that this very valuable forage, turf and conservation grass, which occupies 30 million plus acres in the south-eastern USA, is toxic to most livestock and wild animals. It is further established that this grass is toxic due to the fungus that resides within the plant as an endophyte, which form what is referred to as a symbiotic association. This symbiotic association is further distinguished as being beneficial since the fungus provides the necessary toxins, growth factors, and drought defences necessary for persistence under grazing pressures. What is not known is how environmental stimuli are perceived and communicated to each of the partners within this symbiotic association to adverse conditions. We were invited to review the manner of communication between the fungus and the grass. We review the developmental and morphological nature of the niche that house the fungus as an endophyte and describe the positive benefits derived from the association. We also review information on the nature of signalling between the fungus metabolism and the grass metabolism and the work that has led to how these signals operate to effects a response to environmental changes. Additional information is discussed in terms of how these signals crosstalk to amplify any necessary metabolites to overcome stresses. Thus signalling and crosstalk provide the necessary communication between these two distinctly different organisms for ecological success.