DOI: 10.5061/dryad.4mw6m90dn
title: Mycorrhizae influence plant vegetative and floral traits and intraspecific trait variation

description: Premise. Arbuscular mycorrhizal fungi (AMF) can strongly influence host
 plant vegetative growth, but less is known about AMF effects on other
 plant traits, the relative impacts of AMF on vegetative growth versus
 floral traits, or AMF-induced intraspecific variation in traits. Key
 results. AMF species varied in their effects on host plants, from negative
 to positive effects. AMF often had inconsistent effects on vegetative
 biomass versus floral traits, and therefore quantifying one or the other
 may provide a misleading representation of potential AMF effects. AMF
 treatments generated key variation in plant traits, especially floral
 traits, with potential consequences for plant-pollinator
 interactions. Given increased intraspecific trait variation in
 Linum lewisii plants across AMF species compared to uninoculated
 individuals or single AMF treatments, local AMF diversity and their host
 plant associations may scale up to influence community-wide patterns of
 trait variation and species interactions. Conclusions. These results have
 implications for predicting how aboveground communities are affected by
 belowground communities. Including AMF effects on not just host plant
 biomass but also functional traits and trait variation will deepen our
 understanding of community structure and function, including pollination.
description: In an experimental greenhouse study, we inoculated seven species
 of native perennial wildflowers (Achillea millefolium, Erigeron speciosus,
 Geranium viscosissimum, Linum lewisii, Lupinus argenteus, Monarda
 fistulosa, and Phacelia hastata) with six species of AMF (Acaulospora
 morrowiae, Claroideoglomus etunicatum, Diversispora spurca, Funneliformis
 mosseae, Gigaspora gigantea, and Rhizophagus clarus) in a factorial
 design, including un-inoculated individuals as controls. Seeds were
 sourced locally from the Bridger Plant Materials Center, which has
 selected and released large quantities of native wildflower species for
 pollinator enhancement plantings for the region (southwest Montana, United
 States). In the unlikely event that genetically-related seeds were
 acquired, they would have been distributed randomly among treatments by
 mixing within large seed batches. Plant species were selected for their
 known ability to grow in greenhouse conditions (e.g., Burkle et al.,
 2020), verified root associations with AMF (data not shown), requirement
 for insect pollinators for seed production (Schaal and Leverich, 1980;
 Cruden et al., 1984; Pardee et al., 2018), and diversity of growth forms
 which may reflect varying investment strategies and provide some initial
 insight to the potential for life history responses to AMF. We grew seven
 replicates of each of the species combinations in 1:1 mix of fine sand and
 topsoil (pasteurized), for a total of 343 pots (6.9 cm dia x 35.6 cm l).
 AMF species were obtained from INVAM
 (https://invam.ku.edu), and, because of the lack of
 tight association at the level of plant species between plant community
 composition and AMF community composition (Davison et al., 2011; Zobel and
 Öpik, 2014; Horn et al., 2017) species were selected based on their
 phylogenetic differences (the six species belonged to five different
 families) and potential for ecological differences  (Maherali and
 Klironomos, 2007; https://invam.ku.edu/species-descriptions). AMF were
 maintained in cultures using Sorghum sudanese as a host plant, and
 inoculum for the study included soil and colonized root fragments. After
 adding 175 mL of the soil mix to the bottom of each pot, the inoculum was
 added as 16 mL (1 tablespoon) mixed with 374 mL soil, and covered by an
 additional 25 mL of soil. Three seeds of a single species were added to
 each pot and allowed to germinate. Lupinus argenteus seeds were scarified
 to increase germination. Growth conditions included a day /night
 temperature regime averaging 26°C / 15°C and a 16 h photoperiod with
 supplemental lighting provided by high pressure sodium lamps. Seedlings
 were thinned to one individual between 10 and 14 days after emergence.
 Each pot was fertilized once per week with 20 mL of ¼ strength Hoagland’s
 solution, beginning 3 weeks after seeding. Pots were randomly arranged on
 the bench, and rotated weekly for the duration of the experiment. We
 controlled pests with insecticidal soap (Safer brand) as needed. This
 experiment ran for 22 weeks, from March 1 to August 12, 2013. We allowed
 the experiment to run as long as possible without plant individuals
 becoming root-bound; the experiment was terminated when it was clear that
 no additional plant individuals would flower during the growing
 season. For each plant, we recorded plant survival,
 and, if the plant flowered, we recorded date of first bud, date of first
 flower, height at first flower, mean flower size (based on width or area
 of three flowers, depending on forb species), and flower production (the
 total number of flowers produced by the plant). At the end of the study,
 the aboveground biomass of each plant was separated into floral biomass
 and vegetative biomass, dried, and weighed.