APS Abstract of Presentation

Linking models of resource-based tradeoffs in trees: An assessment of growth, defense, carbon allocation patterns, and potential ectomycorrhizal regulation in paper birch
N. M. KLECZEWSKI (1), P. Bonello (1)
(1) The Ohio State University
Phytopathology 98:S82

Resource availability affects tradeoffs between primary and secondary metabolism such that rapidly growing trees characteristic of fertile soils have lower levels of secondary metabolites and vice versa. Decreased accumulation of secondary metabolites increases susceptibility of trees to disease and drought stress. Soil fertility levels also are often negatively correlated with ectomycorrhizal (EM) abundance on tree root systems, which decreases the ability of trees to obtain water and limiting nutrients. The relationship between metabolic tradeoffs in response to soil fertility and regulation of EM is unknown. We studied metabolic tradeoffs, internal carbon allocation, and EM associations of paper birch seedlings in a controlled greenhouse setting. A fully factorial design with soil type, fertilization, and drought as treatments was used. Overall growth, carbon allocation, soluble carbohydrates, soluble phenolics, and lignin were measured for foliage and root material. Seedling growth rates increased with fertilization, while levels of foliar phenolics and root-to-shoot ratios decreased. Root phenolics and lignin decreased upon fertilization of subsoil, but increased in fertilized topsoil. EM abundance was strongly negatively correlated with levels of root phenolics and lignin, indicating that the host may regulate its EM associations by manipulating these general defense responses in complex interactions with resource availability.

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