Andrea Polle & Cara Haney & Shawn Mansfield
PhD students: Steven Dreischhoff and Ishani Shankar Das

Interaction of ectomycorrhizal fungi with poplar roots enhance poplar leaf defense and decrease the fitness of leaf-feeding herbivores. The beneficial fungi influence host nitrogen metabolism and secondary compounds in leaves. (For details, please look at: Kaling et al. (2018) Mycorrhiza-triggered transcriptomic and metabolomic networks impinge on herbivore fitness. Plant Physiology, 176: 2639-2656). It remains poorly understood, how fungi associated with roots impact defense metabolism of above ground tissues. Ongoing research indicates that mycorrhizal fungi have positive effects on defense, not only for typical host plants, but also for non-hosts such as Arabidopsis. Differences in the xylem sap of mycorrhizal and non-mycorrhizal poplars suggest that mobile signals may travel from the root to the shoot. The goal of this project is to identify the signaling compounds and molecular mechanisms that result in mycorrhizal-induced systemic resistance in host and non-host systems.


The project includes two positions for PhD researchers, who will closely collaborate. The task will be:

M1a) to characterize mycorrhizal defense activation in leaves of Arabidopsis by genetic methods and to compare the signaling pathway with that in poplar. Transgenic methods will be used to establish causal relationships between leaf signals and defense in poplar. Part of the work will be conducted at UBC (Vancouver) in the laboratory of Cara Haney.

M1b) to characterize the function of candidate proteins for defense activation in the xylem sap of poplar. The number of candidates will be reduced by testing a range of different conditions on xylem sap composition and defense responses in bioassays. The remaining candidates will be functionally characterized by transgenic methods. The candidates will also be used for genome-wide association studies in poplar collection at UBC (Vancouver) in the laboratory of Shawn Mansfield.