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8 - An overview of arbuscular mycorrhizal fungal composition, distribution and host effects from a tropical moist forest
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- By Edward Allen Herre, Smithsonian Tropical Research Institute, Damond Kyllo, Smithsonian Tropical Research Institute, Scott Mangan, Smithsonian Tropical Research Institute and Indiana University, Rebecca Husband, Smithsonian Tropical Research Institute and University of York, Luis C. Mejia, Smithsonian Tropical Research Institute, Ahn-Heum Eom, Smithsonian Tropical Research Institute and Korea National University of Education
- Edited by David Burslem, University of Aberdeen, Michelle Pinard, University of Aberdeen, Sue Hartley, University of Sussex
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- Book:
- Biotic Interactions in the Tropics
- Published online:
- 25 August 2009
- Print publication:
- 08 September 2005, pp 204-225
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Summary
Introduction
Arbuscular mycorrhizal fungi (AMF) (Zygomycetes) are an ancient group, dating back to the invasion of land surfaces by plants. Currently, they are perhaps the most abundant soil fungi, and they form intimate relationships with the roots of the vast majority of terrestrial plant species across the planet. These fungal symbionts generally play a mutualistic role, aiding the host plant primarily by enhancing the acquisition of soil nutrients, particularly phosphorus (P). In addition, AMF species often affect plant hormone production/induction (Allen et al. 1980), resistance to root pathogens (Newsham et al. 1995); water uptake (Kyllo et al. 2003) and soil structure (Andrade et al. 1998; Rillig & Allen 1999). In return, all AMF species obligately depend on the host plant for photosynthetically fixed carbon. Given their obligate dependence, AMF are influenced by their hosts at essentially every phase in their life history – hyphal development, sporulation and spore germination (Hetrick & Bloom 1986; Sanders & Fitter 1992; Bever et al. 1996). On the other hand, the degree of mycorrhizal dependence often varies widely among the host plant species in a community (Janos 1980a; Azcon & Ocampo 1981; Hetrick et al. 1992; Kiers et al. 2000).
A central and still largely unanswered question is the degree to which host plant and AMF species influence each other's community composition in natural systems. Fundamentally, for community effects to occur, different combinations of host and AMF species must produce different outcomes of survival and growth.
9 - Tropical plants as chimera: some implications of foliar endophytic fungi for the study of host-plant defence, physiology and genetics
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- By Edward Allen Herre, Smithsonian Tropical Research Institute, Sunshine A. Van Bael, Smithsonian Tropical Research Institute, Zuleyka Maynard, Smithsonian Tropical Research Institute, Nancy Robbins, Smithsonian Tropical Research Institute, Joseph Bischoff, Rutgers University, Anne E. Arnold, Smithsonian Tropical Research Institute and Duke University, Enith Rojas, Smithsonian Tropical Research Institute, Luis C. Mejia, Smithsonian Tropical Research Institute, Roberto A. Cordero, Smithsonian Tropical Research Institute, Catherine Woodward, Smithsonian Tropical Research Institute, Damond A. Kyllo, Smithsonian Tropical Research Institute
- Edited by David Burslem, University of Aberdeen, Michelle Pinard, University of Aberdeen, Sue Hartley, University of Sussex
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- Book:
- Biotic Interactions in the Tropics
- Published online:
- 25 August 2009
- Print publication:
- 08 September 2005, pp 226-238
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- Chapter
- Export citation
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Summary
Introduction
Fungal endophytes are defined as those fungi that live inside plant tissues (e.g. roots, stems, leaves) without causing apparent harm to their host (see Wilson 1995). Although we will also mention stem-associated endophytes (see Evans et al. 2003) and endophytes associated with roots (mycorrhizae; see Herre et al., this volume), throughout this chapter, we will focus primarily on the implications of recent studies of the endophytic fungi that live inside plant leaf tissue. These foliar endophytes are extremely diverse phylogenetically and have been documented in nearly all plants sampled (e.g. mosses, liverworts, ferns, conifers and angiosperms; Carroll 1988; Clay 1988; Petrini 1991; Schultess & Faeth 1998; Frohlich & Hyde 1999; Stone et al. 2000; Arnold et al. 2000; Arnold 2002; Arnold et al. 2003; Davis et al. 2003). Despite the growing recognition of their wide distribution across plant taxa, basic attributes of their biology are still poorly understood. Specifically, endophyte diversity, distributions, life cycles, interactions with hosts and other fungi, and their net chemical, physiological and ecological influences are only beginning to be appreciated and studied. This is particularly true in the extremely diverse tropics.
The best-studied endophytes are ascomycetes belonging to the family Clavicipitaceae. These fungi grow throughout the aboveground tissues of some temperate grass species (e.g. Festuca arundinacea, see Clay & Schardl 2002). Typically, in infected individuals, a single fungal genotype infects a single plant individual.