Effect of Water Stress and Fungal Inoculation on Monoterpene Emission from an Historical and a New Pine Host of the Mountain Pine Beetle

Abstract

The mountain pine beetle (Dendroctonus ponderosae, MPB) has killed millions of lodgepole pine (Pinus contorta) trees in Western Canada, and recent range expansion has resulted in attack of jack pine (Pinus banksiana) in Alberta. Establishment of MPB in the Boreal forest will require use of jack pine under a suite of environmental conditions different from those it typically encounters in its native range. Lodgepole and jack pine seedlings were grown under controlled environment conditions and subjected to either water deficit or well watered conditions and inoculated with Grosmannia clavigera, a MPB fungal associate. Soil water content, photosynthesis, stomatal conductance, and emission of volatile organic compounds (VOCs) were monitored over the duration of the six-week study. Monoterpene content of bark and needle tissue was measured at the end of the experiment. β-Phellandrene, the major monoterpene in lodgepole pine, was almost completely lacking in the volatile emission profile of jack pine. The major compound in jack pine was α-pinene. The emission of both compounds was positively correlated with stomatal conductance. 3-Carene was emitted at a high concentration from jack pine seedlings, which is in contrast to monoterpene profiles of jack pine from more southern and eastern parts of its range. Fungal inoculation caused a significant increase in total monoterpene emission in water deficit lodgepole pine seedlings right after its application. By 4 weeks into the experiment, water deficit seedlings of both species released significantly lower levels of total monoterpenes than well watered seedlings. Needle tissue contained lower total monoterpene content than bark. Generally, monoterpene tissue content increased over time independent from any treatment. The results suggest that monoterpenes that play a role in pine-MPB interactions differ between lodgepole and jack pine, and also that they are affected by water availability.

The Differential Effects of the Blue-Stain Fungus Leptographium qinlingensis on Monoterpenes and Sesquiterpenes in the Stem of Chinese White Pine (Pinus armandi) Saplings

“…In our experiment, total monoterpene concentrations in the phloem and xylem in P. armandi saplings after inoculation of the blue-stain fungus L. qinlingensis were significantly higher than in both control and untreated saplings. The results are in accordance with several previous reports in conifers [19][20][21][22][23][24][25]31], where total monoterpene concentrations increased significantly after the inoculation of blue-stain fungi. However, the comparison of the increases in total monoterpene concentrations found in this study with the results of previous studies may be influenced by differences in experimental design, such as differences in the treatment type, the age of the tree, and the sampling time points [21,31].…”

Emissions of BVOC from lodgepole pine in response to mountain pine beetle attack in high and low mortality forest stands

“…At the MRS site, lodgepoles appear to be more resilient to the MPB and/or its fungal symbiont, the blue stain fungus (of which there are at least two species). Although, to our knowledge, little is known about whether specific chemotypes of Pinus contorta are better equipped to survive MPB attack, it has been known for some time that MT emission profiles observed both in tree resin and in emissions are unique between most subspecies/varieties of lodgepole (e.g., Zavarin et al, 1969;Lusebrink et al, 2011). Even within a seemingly homogenous zone, several chemotypes of a given species may be present, and the relative ratios of compounds detected in ambient air have been observed to reflect this diversity (Bäck et al, 2012).…”

“…None of the trees sampled had obvious fire damage, and so this effect is not suspected to play a role in observed differences between Chimney Park and MRS. It is not known which species of blue stain fungus predominate either site, while it is known that some species are more virulent than others (Lusebrink et al, 2011), and so this factor cannot be excluded when pondering the difference in apparent MPB resilience between the sites.…”

“…The presence or absence of water stress must be considered when evaluating differences between the sites, as water deficit has been shown to decrease emissions of MT in lodgepole seedlings and may also affect tree resistance to MPB (Lusebrink et al, 2011;Safranyik et al, 2010). We analyzed precipitation data for the 5-and 10-yr period prior to the start of sampling at both the Chimney Park and MRS sites (using PRISM precipitation data, PRISM Climate Group, Oregon State University, http://prism.oregonstate.edu, created 4 Feburary 2004), and found that both sites had received at or above 100 % of their 1971-2000 average values during the study time periods (Table 1), although it should be noted that average annual precipitation at CP is ∼ 60 % of the average for MRS.…”

Mountain Pine Beetles Colonizing Historical and Naïve Host Trees Are Associated with a Bacterial Community Highly Enriched in Genes Contributing to Terpene Metabolism

“…1). It has now colonized the hybrid crossings of P. contorta and jack pine, Pinus banksiana Lamb., and also the pure P. banksiana trees in this region (13,14). These trees are contiguous with P. banksiana forests throughout all of southern Canada east of the Rocky Mountains, connecting with eastern white pine, Pinus strobus L., and red pine, Pinus resinosa Sol.…”