title: Ecological implications of anti-pathogen effects of tropical fungal endophytes and mycorrhizae.
abstract: We discuss studies of foliar endophytic fungi (FEF) and arbuscular mycorrhizal fungi (AMF) associated with Theobroma cacao in Panama. Direct, experimentally controlled comparisons of endophyte free (E-) and endophyte containing (E+) plant tissues in T. cacao show that foliar endophytes (FEF) that commonly occur in healthy host leaves enhance host defenses against foliar damage due to the pathogen (Phytophthora palmivora). Similarly, root inoculations with commonly occurring AMF also reduce foliar damage due to the same pathogen. These results suggest that endophytic fungi can play a potentially important mutualistic role by augmenting host defensive responses against pathogens. There are two broad classes of potential mechanisms by which endophytes could contribute to host protection: (1) inducing or increasing the expression of intrinsic host defense mechanisms and (2) providing additional sources of defense, extrinsic to those of the host (e.g., endophyte-based chemical antibiosis). The degree to which either of these mechanisms predominates holds distinct consequences for the evolutionary ecology of host-endophyte-pathogen relationships. More generally, the growing recognition that plants are composed of a mosaic of plant and fungal tissues holds a series of implications for the study of plant defense, physiology, and genetics.
authors.affiliation: Smithsonian Tropical Research Institute, Unit 0948, APO AA 34002-0948, USA. HERREA@si.edu
authors.forename: Edward Allen
authors.initials: EA
authors.lastname: Herre
authors.forename: Luis C
authors.initials: LC
authors.lastname: Mejía
authors.forename: Damond A
authors.initials: DA
authors.lastname: Kyllo
authors.forename: Enith
authors.initials: E
authors.lastname: Rojas
authors.forename: Zuleyka
authors.initials: Z
authors.lastname: Maynard
authors.forename: Andre
authors.initials: A
authors.lastname: Butler
authors.forename: Sunshine A
authors.initials: SA
authors.lastname: Van Bael
mesh_terms: D002099:Cacao / Q000276:immunology / Q000382:microbiology*; D004463:Ecology; D038821:Mycorrhizae / Q000276:immunology / Q000502:physiology*; D010176:Panama; D010838:Phytophthora / Q000276:immunology; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology*; D013559:Symbiosis; D014329:Tropical Climate