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Title: Phylogenetic conservatism of mycoparasitism and its contribution to pathogen antagonism

Closely related species are expected to have similar functional traits due to shared ancestry and phylogenetic inertia. However, few tests of this hypothesis are available for plant‐associated fungal symbionts. Fungal leaf endophytes occur in all land plants and can protect their host plant from disease by a variety of mechanisms, including by parasitizing pathogens (e.g., mycoparasitism). Here, we tested whether phylogenetic relatedness among species ofCladosporium, a widespread genus that includes mycoparasitic species, predicts the effect of this endophyte on the severity of leaf rust disease. First, we used congruence among different marker sequences (i.e., genealogical concordance phylogenetic species recognition criterion) to delimit species ofCladosporium. Next, in a controlled experiment, we quantified both mycoparasitism and disease modification for the selectedCladosporiumspecies. We identified 17 species ofCladosporium; all the species reduced rust disease severity in our experiment.Cladosporiumphylogeny was a significant predictor of mycoparasitism. However, we did not observe a phylogenetic effect on disease severity overall, indicating that other mechanism/s operating independently of shared ancestry also contributed to endophyte effects on disease severity. Indeed, a second experiment showed thatCladosporiumendophyte exudates (no live organism) from divergent species groups equally reduced disease severity. Our results reveal that multiple mechanisms contribute to the protective effects of an endophyte against a plant pathogen, but not all traits underlying these mechanisms are phylogenetically conserved.

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Author(s) / Creator(s):
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Date Published:
Journal Name:
Molecular Ecology
Page Range / eLocation ID:
p. 3018-3030
Medium: X
Sponsoring Org:
National Science Foundation
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    Consumer‐resource interactions are often influenced by other species in the community, such as when neighbouring plants increase or reduce herbivory to a focal plant species (known as associational effects). The many studies on associational effects between a focal plant and some neighbour have shown that these effects can vary greatly in strength and direction. But because almost all of these studies measure associational effects from only one or two neighbour species, we know little about the actual range of associational effects that a plant species might encounter in a natural setting. This makes it difficult to determine how important effects of neighbours are in real field settings, and how associational effects might interact with competition and other processes to influence plant community composition.

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  2. Abstract Aim

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  4. Abstract

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