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- A. Elizabeth Arnold
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721; and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama
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- Luis Carlos Mejía
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721; and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama
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- Damond Kyllo
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721; and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama
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- Enith I. Rojas
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721; and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama
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- Zuleyka Maynard
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721; and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama
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- Nancy Robbins
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721; and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama
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- Edward Allen Herre
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721; and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panama
説明
<jats:p> Every plant species examined to date harbors endophytic fungi within its asymptomatic aerial tissues, such that endophytes represent a ubiquitous, yet cryptic, component of terrestrial plant communities. Fungal endophytes associated with leaves of woody angiosperms are especially diverse; yet, fundamental aspects of their interactions with hosts are unknown. In contrast to the relatively species-poor endophytes that are vertically transmitted and act as defensive mutualists of some temperate grasses, the diverse, horizontally transmitted endophytes of woody angiosperms are thought to contribute little to host defense. Here, we document high diversity, spatial structure, and host affinity among foliar endophytes associated with a tropical tree ( <jats:italic>Theobroma cacao</jats:italic> , Malvaceae) across lowland Panama. We then show that inoculation of endophyte-free leaves with endophytes isolated frequently from naturally infected, asymptomatic hosts significantly decreases both leaf necrosis and leaf mortality when <jats:italic>T. cacao</jats:italic> seedlings are challenged with a major pathogen ( <jats:italic>Phytophthora</jats:italic> sp.). In contrast to reports of fungal inoculation inducing systemic defense, we found that protection was primarily localized to endophyte-infected tissues. Further, endophyte-mediated protection was greater in mature leaves, which bear less intrinsic defense against fungal pathogens than do young leaves. <jats:italic>In vitro</jats:italic> studies suggest that host affinity is mediated by leaf chemistry, and that protection may be mediated by direct interactions of endophytes with foliar pathogens. Together, these data demonstrate the capacity of diverse, horizontally transmitted endophytes of woody angiosperms to play an important but previously unappreciated role in host defense. </jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 100 (26), 15649-15654, 2003-12-11
Proceedings of the National Academy of Sciences