title: Tree genotype and genetically based growth traits structure twig endophyte communities.
abstract: OBJECTIVE
  Fungal endophytes asymptomatically inhabit plant tissues where they have mutualistic, parasitic, or commensal relationships with their hosts. Although plant-fungal interactions at the genotype scale have broad ecological and evolutionary implications, the sensitivity of endophytes in woody tissues to differences among plant genotypes is poorly understood. We hypothesize that (1) endophyte communities in Populus angustifolia (Salicaceae) twigs vary among tree genotypes, (2) endophyte variation is linked to quantitative tree traits, and (3) tree genotype influences interspecific fungal interactions.
  
  
  METHODS
  Endophytes were isolated from twigs of replicated P. angustifolia genotypes in a common garden and characterized with PCR-RFLP and DNA sequencing. Twig length and diameter, aboveground tree biomass, and condensed tannins were also quantified.
  
  
  RESULTS
  (1) Aspects of fungal community structure, including composition and total isolation frequency (i.e., abundance), varied among genotypes. (2) Aboveground biomass and twig diameter were positively associated with isolation frequency and covaried with composition, whereas twig length and condensed tannin concentration were not significantly correlated to endophytes. (3) Fungal co-occurrence patterns suggested negative species interactions, but the presence of significant co-occurrences was genotype dependent.
  
  
  CONCLUSIONS
  The species is often assumed to be the most important ecological unit; however, these results indicate that genetically based trait variation within a species can influence an important community of associated organisms. Given the dominance of plants as primary producers and the ubiquity of endophytes, the effect of host genetic variation on endophytes has fundamental implications for our understanding of terrestrial ecosystems.
authors.affiliation: Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, Arizona 86011-5640 USA.
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Lamit
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Lau
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Sthultz
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Wooley
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Whitham
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Gehring
mesh_terms: D001483:Base Sequence; D018533:Biomass; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D060026:Endophytes / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D005658:Fungi / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D014644:Genetic Variation; D005838:Genotype; D008969:Molecular Sequence Data; D010641:Phenotype; D018520:Plant Shoots / Q000737:chemistry / Q000254:growth & development / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D032107:Populus / Q000737:chemistry / Q000254:growth & development / Q000382:microbiology*; D044945:Proanthocyanidins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013559:Symbiosis; D014197:Trees
chemical_list: D004271:DNA, Fungal; D044945:Proanthocyanidins
keywords: Populus angustifolia; Salicaceae; aboveground biomass; co-occurrence analysis; condensed tannins; endophyte; tree genotype