title: Host Plant Physiology and Mycorrhizal Functioning Shift across a Glacial through Future [CO2] Gradient.
abstract: Rising atmospheric carbon dioxide concentration ([CO2]) may modulate the functioning of mycorrhizal associations by altering the relative degree of nutrient and carbohydrate limitations in plants. To test this, we grew Taraxacum ceratophorum and Taraxacum officinale (native and exotic dandelions) with and without mycorrhizal fungi across a broad [CO2] gradient (180-1,000 µL L-1). Differential plant growth rates and vegetative plasticity were hypothesized to drive species-specific responses to [CO2] and arbuscular mycorrhizal fungi. To evaluate [CO2] effects on mycorrhizal functioning, we calculated response ratios based on the relative biomass of mycorrhizal (MBio) and nonmycorrhizal (NMBio) plants (RBio= [MBio- NMBio]/NMBio). We then assessed linkages between RBioand host physiology, fungal growth, and biomass allocation using structural equation modeling. For T. officinale, RBioincreased with rising [CO2], shifting from negative to positive values at 700 µL L-1[CO2] and mycorrhizal effects on photosynthesis and leaf growth rates drove shifts in RBioin this species. For T. ceratophorum, RBioincreased from 180 to 390 µL L-1and further increases in [CO2] caused RBioto shift from positive to negative values. [CO2] and fungal effects on plant growth and carbon sink strength were correlated with shifts in RBioin this species. Overall, we show that rising [CO2] significantly altered the functioning of mycorrhizal associations. These symbioses became more beneficial with rising [CO2], but nonlinear effects may limit plant responses to mycorrhizal fungi under future [CO2]. The magnitude and mechanisms driving mycorrhizal-CO2responses reflected species-specific differences in growth rate and vegetative plasticity, indicating that these traits may provide a framework for predicting mycorrhizal responses to global change.
authors: Ecology and Evolutionary Biology Department, University of Kansas, Lawrence, Kansas 66045 kbecklin@ku.edu.
authors: Katie M
authors: 0000-0003-3173-3357
authors: KM
authors: Becklin
authors: Ecology and Evolutionary Biology Department, University of Kansas, Lawrence, Kansas 66045.
authors: George W R
authors: GW
authors: Mullinix
authors: Ecology and Evolutionary Biology Department, University of Kansas, Lawrence, Kansas 66045.
authors: Joy K
authors: JK
authors: Ward
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D002980:Climate; D057231:Climate Change; D004463:Ecology / Q000379:methods / Q000639:trends; D005544:Forecasting; D046448:Ice Cover; D038821:Mycorrhizae / Q000502:physiology*; D018521:Plant Physiological Phenomena; D010944:Plants / Q000145:classification / Q000382:microbiology*; D013045:Species Specificity; D013559:Symbiosis; D031205:Taraxacum / Q000145:classification / Q000254:growth & development / Q000382:microbiology
chemical_list: D002245:Carbon Dioxide