Root bacterial endophytes alter plant phenotype, but not physiology.
Plant traits, such as root and leaf area, influence how plants interact with their environment and the diverse microbiota living within plants can influence plant morphology and physiology. Here, we explored how three bacterial strains isolated from thePopulusroot microbiome, influenced plant phenotype. We chose three bacterial strains that differed in predicted metabolic capabilities, plant hormone production and metabolism, and secondary metabolite synthesis. We inoculated each bacterial strain on a single genotype ofPopulus trichocarpaand measured the response of plant growth related traits (root:shoot, biomass production, root and leaf growth rates) and physiological traits (chlorophyll content, net photosynthesis, net photosynthesis at saturating light-Asat, and saturating CO2-Amax). Overall, we found that bacterial root endophyte infection increased root growth rate up to 184% and leaf growth rate up to 137% relative to non-inoculated control plants, evidence that plants respond to bacteria by modifying morphology. However, endophyte inoculation had no influence on total plant biomass and photosynthetic traits (net photosynthesis, chlorophyll content). In sum, bacterial inoculation did not significantly increase plant carbon fixation and biomass, but their presence altered where and how carbon was being allocated in the plant host.
Department of Ecology & Evolutionary Biology, University of Tennessee-Knoxville , Knoxville, Tennessee , United States.
Jeremiah A
JA
Henning
Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, TN , United States.
David J
DJ
Weston
Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, TN , United States.
Dale A
DA
Pelletier
Joint Institute for Biological Sciences, University of Tennessee , Oak Ridge, TN , United States.
Collin M
0000-0002-7804-5044
CM
Timm
Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, TN , United States.
Sara S
SS
Jawdy
Department of Ecology & Evolutionary Biology, University of Tennessee-Knoxville, Knoxville, Tennessee, United States; Center for Macroecology, Evolution, and Climate, The Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
Aimée T
AT
Classen
Bacterial endophytes; Burkholderia; Plant functional traits; Plant morphology; Populus trichocarpa; Pseudomonas fluorescens; Trait plasticity