Ectomycorrhizal fungal species differentially affect the induced defensive chemistry of lodgepole pine
Plants interact simultaneously with multiple organisms, including ectomycorrhizal (EM) fungal symbionts which benefit plants by facilitating resource acquisition. Yet, their role in induced plant defenses that rely on the allocation of plant resources has received little attention. We investigated whether EM fungi can affect the induction of defense-related monoterpenes in greenhouse-grown lodgepole pine (Pinus contorta var. latifolia) seedlings, and whether such effects differed between EM fungal species occurring alone or in combination. Fungal interactions on growth media were also assessed to complement the greenhouse study. Our study revealed that the production of certain monoterpenes is influenced by the fungal species colonizing pine roots. Furthermore, pine seedlings did not necessarily benefit from having associations with multiple EM fungi, as we found contrasting effects of single vs. multiple species of fungi on induced monoterpene responses. Finally, monoterpene responses were altered when early-colonizing species inhibited the colonization or development of later-arriving species. We conclude that the presence of EM fungi can impact host susceptibility to insect and pathogen attack, suggesting that seedlings establishing in areas lacking fungi that promote the induction of tree defense chemicals may suffer from increased susceptibility to future pest damage.
KeywordsCenococcum geophilum Dendroctonus ponderosae Laccaria bicolor Pinus contorta
Funding for this research was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC)—Discovery Award to N.E. We thank Drs. Justine Karst and Janusz Zwiazek for their feedback on the methodology used in the experiments. We also acknowledge that all research presented in the manuscript was conducted in accordance with all applicable laws and rules set forth by the provincial (Alberta) and federal governments and the University of Alberta, and all necessary permits were in hand when the research was conducted.
Author contribution statement
SSK, JAC, and NE conceived and designed the experiments. SSK performed the experiments and SSK and JAC analyzed the data. SSK, JAC, and NE wrote the manuscript.
- Abramoff MD, Magalhaes PJ, Ram SJ (2004) Image processing with ImageJ. Biophoton Intern 11:36–42Google Scholar
- Bradbury SM, Danielson RM, Visser S (1998) Ectomycorrhizas of regenerating stands of lodgepole pine (Pinus contorta). Can J Bot 76:218–227Google Scholar
- Cale JA, Muskens M, Najar A, Ishangulyyeva G, Hussain A, Kanekar SS, Klutsch JG, Taft S, Erbilgin N (2017) Rapid monoterpene induction promotes the susceptibility of a novel host pine to mountain pine beetle colonization but not to beetle-vectored fungi. Tree Physiol 37:1597–1610CrossRefPubMedGoogle Scholar
- Erbilgin N, Cale JA, Lusebrink I, Najar A, Klutsch JG, Sherwood P, Bonello PE, Evenden ML (2017a) Water-deficit and fungal infection can differentially affect the production of different classes of defense compounds in two host pines of mountain pine beetle. Tree Physiol 37:338–350CrossRefPubMedGoogle Scholar
- Goodman DM (1996) A manual of concise descriptions of north american ectomycorrhizae. Mycologue Publications, and the Canada-BC Forest Resource Development Agreement, Pacific Forestry Centre, Victoria, B.C., SidneyGoogle Scholar
- R Core Team (2016) R: a language and environment for statistical computing. version 3.3.2. R Foundation for Statistical Computing, Vienna. http://www.R-project.org/
- Smith SE, Read DJ (2008) Mycorrhizal Symbiosis, 3rd edn. Elsevier, New YorkGoogle Scholar