Abiotic stresses and endophyte effects

Authors: Belesky, David; WEST, CHARLES - UNIVERSITY OF ARKANSAS

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 8/12/2004
Publication Date: 1/7/2005
Citation: Belesky, D.P., West, C.P. 2005. Abiotic stresses and endophyte effects. On-line Book, Available: "forages.oregonstate.edu/is/tfis/chapter/Chapter05/TFIS_Chapter4.pdf".

Interpretive Summary:

Technical Abstract: Tall fescue is a major forage grass grown throughout the southeastern US and is adapted over most of the US east of the Mississippi River. The grass is host to an endophytic fungus that has significant influence of the ecological function of host in natural and agricultural situations. Research on tall fescue for much of the past 30 years focused on deleterious effects of endophyte infection on livestock performance and metabolism to gain some understanding of the toxicosis syndrome and to develop management practices to optimize livestock production. Emergent evidence suggested that infection by endophyte (E+) provided host plants with means to grow and persist under conditions of marginal water and nutrient supply whereas plants lacking endophyte (E-) were likely to be at a competitive and adaptive disadvantage. Most tall fescue plants in wild and naturalized stands are endophyte infected, which supports the premise that endophyte infection increased plant fitness and competitiveness in stressful environments. Enhanced ecological fitness may involve grazing deterrence (through production of anti-herbivory compounds), which allows greater survival of plant storage tissues, primarily stem bases, growing points and roots. Endophyte-infected tall fescue plants might be larger, having a competitive advantage in resource capture (i.e., water and nutrients) and ability to tolerate grazing in stressful environments. Other evidence suggested that endophyte promotes survival even in the absence of grazing. Responses indicate a complex relationship between the host plant and endophytic mutualist such that endophyte has both direct and indirect effects on plant production and persistence. We review the current understanding of host plant-endophyte interactions with emphasis on tall fescue responses to abiotic stresses.