Lee, Mei-Ho , Callahan, Hilary , Palmer, Matthew, I. , Patterson, Angelica , Comas, Louise .
Mycorrhizal colonization elicits limited plasticity in functional root traits of maple and oak.
Interactions between plant roots and symbiotic fungi are critical but poorly understood components of belowground ecology. To better understand how mycorrhizae affect tree roots, we experimentally investigated the effects of mycorrhizal colonization on Acer and Quercus fine root traits: diameter, tissue density, specific root length (SRL), tip frequency, and N content. The plasticity of root traits in the absence of mycorrhizal fungi may be relevant to whether and how plants compensate in their absence. Roots of 16 Acer rubrum and 15 Quercus rubra seedlings were sterilized with 25% or 50% bleach solution before installation in a greenhouse paired-pot system containing soil with or without mycorrhizal fungi inoculation. After 70 days, newly grown fine roots were collected and their morphology, architecture and N concentrations measured. Both bleach concentrations successfully maintained near-zero mycorrhizal fungi colonization levels in the non-inoculated roots and bleach concentrations had negligible effects on other traits. Inoculated roots had significantly greater root tissue density (~10-20%) but the correlation between colonization level and density was weak (r = 0.23, P < 0.08) and other effects of inoculation on root morphology and architecture were limited. Compared to Acer roots, Quercus roots had greater mean SRL (+65%), smaller mean diameter (-50%), greater mean tip frequency (+12%) and less mean nitrogen content (-12%). These results were compared qualitatively to those from a similar experiment conducted in the field on A. saccharum and Q. rubra using 10% bleach solution. Field-grown roots displayed greater mean root diameter, tissue density and tip frequency but lesser mean SRL. Our techniques might be useful for studying wider range of arbuscular mycorrhizal- and ectomycorrhizal-forming trees and shrubs. A key question is whether the lack of plasticity found here is the general response among woody species.
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1 - Barnard College, Columbia University, Department of Biological Sciences, 3009 Broadway, New York, New York, 10027, USA
2 - Columbia University, Ecology, Evolution, and Environmental Biology, 1200 Amsterdam Ave, New York, NY, 10027, USA
3 - Penn State University, Horticulture and Intercollege Program in Ecology, 102 Tyson Building, University Park, PA, 16802, USA
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM