TY - JOUR
T1 - An endohyphal bacterium (Chitinophaga, Bacteroidetes) alters carbon source use by Fusarium keratoplasticum (F. solani species complex, Nectriaceae)
AU - Shaffer, Justin P.
AU - U'Ren, Jana M.
AU - Gallery, Rachel E.
AU - Baltrus, David A.
AU - Arnold, A. Elizabeth
N1 - Funding Information: We thank the National Science Foundation (NSF DEB-1119758 to AA, NSF DEB-1120205 to James W. Dalling, NSF IOS-1354219 to DB, AA, and RG, NSF-IGERT Fellowship to JS), the Smithsonian Tropical Research Institute (STRI) (Short-term Fellowship to JS), the Mycological Society of America (Forest Fungal Ecology Award to JS), and the Graduate and Professional Student Council (Research Award to JS) and School of Plant Sciences (Pierson Fellowship to JS) at The University of Arizona for supporting this work. Additional support from the School of Plant Sciences and College of Agriculture and Life Sciences at the University of Arizona is gratefully acknowledged. We thank J. DeVore, K. Hockett, and especially A. Ndobegang for lab assistance, K. Arendt, Y.-L. Huang, J. Carlson, K. Hockett, J. Dalling, J. Wright, E. Leigh, G. Gilbert, and N. Zimmerman for helpful discussion, and N. Zimmerman for bioinformatics assistance. This paper represents a portion of the doctoral dissertation research of JS in Plant Pathology and Microbiology at the University of Arizona. Publisher Copyright: © 2017 Shaffer, U'Ren, Gallery, Baltrus and Arnold.
PY - 2017/3/14
Y1 - 2017/3/14
N2 - Bacterial endosymbionts occur in diverse fungi, including members of many lineages of Ascomycota that inhabit living plants. These endosymbiotic bacteria (endohyphal bacteria, EHB) often can be removed from living fungi by antibiotic treatment, providing an opportunity to assess their effects on functional traits of their fungal hosts. We examined the effects of an endohyphal bacterium (Chitinophaga sp., Bacteroidetes) on substrate use by its host, a seed-associated strain of the fungus Fusarium keratoplasticum, by comparing growth between naturally infected and cured fungal strains across 95 carbon sources with a Biolog® phenotypic microarray. Across the majority of substrates (62%), the strain harboring the bacterium significantly outperformed the cured strain as measured by respiration and hyphal density. These substrates included many that are important for plant- and seed-fungus interactions, such as D-trehalose, myo-inositol, and sucrose, highlighting the potential influence of EHB on the breadth and efficiency of substrate use by an important Fusarium species. Cases in which the cured strain outperformed the strain harboring the bacterium were observed in only 5% of substrates. We propose that additive or synergistic substrate use by the fungus-bacterium pair enhances fungal growth in this association. More generally, alteration of the breadth or efficiency of substrate use by dispensable EHB may change fungal niches in short timeframes, potentially shaping fungal ecology and the outcomes of fungal-host interactions.
AB - Bacterial endosymbionts occur in diverse fungi, including members of many lineages of Ascomycota that inhabit living plants. These endosymbiotic bacteria (endohyphal bacteria, EHB) often can be removed from living fungi by antibiotic treatment, providing an opportunity to assess their effects on functional traits of their fungal hosts. We examined the effects of an endohyphal bacterium (Chitinophaga sp., Bacteroidetes) on substrate use by its host, a seed-associated strain of the fungus Fusarium keratoplasticum, by comparing growth between naturally infected and cured fungal strains across 95 carbon sources with a Biolog® phenotypic microarray. Across the majority of substrates (62%), the strain harboring the bacterium significantly outperformed the cured strain as measured by respiration and hyphal density. These substrates included many that are important for plant- and seed-fungus interactions, such as D-trehalose, myo-inositol, and sucrose, highlighting the potential influence of EHB on the breadth and efficiency of substrate use by an important Fusarium species. Cases in which the cured strain outperformed the strain harboring the bacterium were observed in only 5% of substrates. We propose that additive or synergistic substrate use by the fungus-bacterium pair enhances fungal growth in this association. More generally, alteration of the breadth or efficiency of substrate use by dispensable EHB may change fungal niches in short timeframes, potentially shaping fungal ecology and the outcomes of fungal-host interactions.
KW - Endobacteria
KW - Fusaria
KW - Gram-negative
KW - Phenotypic microarray
KW - Substrate use
KW - Symbiosis
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U2 - 10.3389/fmicb.2017.00350
DO - 10.3389/fmicb.2017.00350
M3 - Article
SN - 1664-302X
VL - 8
JO - Frontiers in Microbiology
JF - Frontiers in Microbiology
IS - MAR
M1 - 350
ER -