title: Defoliation of interior Douglas-fir elicits carbon transfer and stress signalling to ponderosa pine neighbors through ectomycorrhizal networks.
abstract: Extensive regions of interior Douglas-fir (Pseudotsuga menziesii var. glauca, IDF) forests in North America are being damaged by drought and western spruce budworm (Choristoneura occidentalis). This damage is resulting from warmer and drier summers associated with climate change. To test whether defoliated IDF can directly transfer resources to ponderosa pine (Pinus ponderosae) regenerating nearby, thus aiding in forest recovery, we examined photosynthetic carbon transfer and defense enzyme response. We grew pairs of ectomycorrhizal IDF 'donor' and ponderosa pine 'receiver' seedlings in pots and isolated transfer pathways by comparing 35 μm, 0.5 μm and no mesh treatments; we then stressed IDF donors either through manual defoliation or infestation by the budworm. We found that manual defoliation of IDF donors led to transfer of photosynthetic carbon to neighboring receivers through mycorrhizal networks, but not through soil or root pathways. Both manual and insect defoliation of donors led to increased activity of peroxidase, polyphenol oxidase and superoxide dismutase in the ponderosa pine receivers, via a mechanism primarily dependent on the mycorrhizal network. These findings indicate that IDF can transfer resources and stress signals to interspecific neighbors, suggesting ectomycorrhizal networks can serve as agents of interspecific communication facilitating recovery and succession of forests after disturbance.
authors: College of Life Sciences, Fujian Agriculture and Forestry University, Jinshan, Fuzhou 350002, P.R. China.
authors: Yuan Yuan
authors: YY
authors: Song
authors: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors: Suzanne W
authors: SW
authors: Simard
authors: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors: Allan
authors: A
authors: Carroll
authors: Department of Microbiology &Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
authors: William W
authors: WW
authors: Mohn
authors: College of Life Sciences, Fujian Agriculture and Forestry University, Jinshan, Fuzhou 350002, P.R. China.
authors: Ren Sen
authors: RS
authors: Zeng
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D038821:Mycorrhizae; D041604:Pinus ponderosa / Q000502:physiology*; D018517:Plant Roots; D028224:Pseudotsuga / Q000502:physiology*; D036226:Seedlings; D013312:Stress, Physiological
chemical_list: D002244:Carbon