Poplar Tree Root Response to Symbiotic Fungus Determines Success of Fungal Colonization
Microbial communities sharing the soil environment with plant roots can have a profound influence on the overall health and vitality of the plant. One well-known example of a beneficial relationship is that formed between forest trees and shrubs and a type of mutualistic fungi known as ectomycorrhizal fungi (ECM). In a compatible reaction, ECM facilitate the plant’s access to nutrients and increase its tolerance to biotic and abiotic stress through formation of an “organ” between fungal hyphae and plant roots called the ECM root tip. However, little is known about the metabolic reprogramming that leads to the development of this hybrid tissue. Researchers at Oak Ridge National Laboratory, funded through the Department of Energy’s Plant-Microbe Interfaces Science Focus Area, characterized the metabolic changes taking place during the interaction between the ECM fungus Laccaria bicolor and two different species of the bioenergy feedstock tree Populus. They found that when P. trichocarpa is colonized by the fungus shifts occurred in aromatic acid, organic acid, and fatty acid metabolism. On the contrary, this metabolic reprogramming was repressed in the incompatible P. deltoides interaction, which was instead characterized by the production of more defense-related secondary metabolites. The results highlight distinct differences in mechanisms controlling compatibility between beneficial and nonbeneficial interactions, and increase understanding of how plant roots respond to the presence of L. bicolor, which determines the outcome of the fungal-host interaction.
Tschaplinski, T. J., J. M. Plett, N. L. Engle, A. Deveau, K. C. Cushman, M. Z. Martin, M. J. Doktycz, G. A. Tuskan, A. Brun, A. Kohler, and M. Martin. 2014. “Populus trichocarpa and Populus deltoides Exhibit Different Metabolomic Responses to Colonization by the Symbiotic Fungus Laccaria bicolor,” Molecular Plant-Microbe Interactions 27(6), 546-56. DOI:10.1094/MPMI-09-13-0286-R.