title: An Endohyphal Bacterium (Chitinophaga, Bacteroidetes) Alters Carbon Source Use byFusarium keratoplasticum(F. solaniSpecies Complex, Nectriaceae).
abstract: 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 (Chitinophagasp., Bacteroidetes) on substrate use by its host, a seed-associated strain of the fungusFusarium 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 importantFusariumspecies. 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.
authors.affiliation: School of Plant Sciences, University of Arizona Tucson, AZ, USA.
authors.forename: Justin P
authors.initials: JP
authors.lastname: Shaffer
authors.affiliation: School of Plant Sciences, University of ArizonaTucson, AZ, USA; Department of Agricultural and Biosystems Engineering, University of ArizonaTucson, AZ, USA.
authors.forename: Jana M
authors.initials: JM
authors.lastname: U'Ren
authors.affiliation: School of Natural Resources and the Environment, University of ArizonaTucson, AZ, USA; Department of Ecology and Evolutionary Biology, University of ArizonaTucson, AZ, USA.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Gallery
authors.affiliation: School of Plant Sciences, University of Arizona Tucson, AZ, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Baltrus
authors.affiliation: School of Plant Sciences, University of ArizonaTucson, AZ, USA; Department of Ecology and Evolutionary Biology, University of ArizonaTucson, AZ, USA.
authors.forename: A Elizabeth
authors.initials: AE
authors.lastname: Arnold
keywords: Gram-negative; endobacteria; fusaria; phenotypic microarray; substrate use; symbiosis