Lodgepole pine provenances differ in chemical defense capacities against foliage and stem diseases

Authors: Wallis, Christopher; REICH, RICHARD - British Colombia Ministry Of Forests And Range; LEWIS, KATHY - University Of North British Columbia; HUBER, DEZENE - University Of North British Columbia

Submitted to: Canadian Journal of Forest Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2010
Publication Date: 11/10/2010
Citation: Wallis, C.M., Reich, R., Lewis, K.J., Huber, D.P. 2010. Lodgepole pine provenances differ in chemical defense capacities against foliage and stem diseases. Canadian Journal of Forest Research. 40:2333-2344.

Interpretive Summary: This paper comprehensively examines the role compounds known as secondary metabolites play in resistance to a variety of pathogens which attack lodgepole pine. Furthermore, it observes variations in the levels of these compounds between distinct pine populations, and links such biochemical variations with increases and decreases in disease susceptibility. Generally, populations from areas thought to have greater historic disease pressures possessed greater levels of defense-associated compounds. This work was conducted in light of recent efforts to move pine populations from warmer to colder climates in an attempt to mitigate effects from climate-change associated temperature increases, and concludes that secondary chemistry should be assessed before moving some pine populations into areas with high disease pressures.

Technical Abstract: Maximization of lodgepole pine (Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson) growth in the face of climate change and new pest outbreaks requires an understanding of the natural variability of quantitative resistance to disease. We assessed trees for the severity of foliar disease symptoms caused by Lophodermella spp. [L. concolor (Dearn.) Darker or L.montivaga Petre.] spp. or Elytroderma deformans (Wier) Darker, and bark disease symptoms caused by Elytroderma or Endocronartium harknessii (J.P. Moore) Y. Hiratsuka in a lodgepole pine seed orchard containing trees from 13 provenances. Foliar and bark levels of lignin, tannins, soluble phenolics, monoterpenes, sesquiterpenes, and diterpenes were also assessed. Greater foliar amounts of lignin, tannin, phenolic acids and lignans, and monoterpenes were associated with increased resistance to one or both foliar pathogens. However, most of the secondary metabolites found in the bark were not associated with resistance to bark diseases. To analyze variations between different provenances, provenances were grouped together by the annual precipitation, temperature, and ecosystem structures of their origins. Provenances originating in ecosystems relatively isolated from large, widespread stands of lodgepole pines were more susceptible to foliar diseases and had less needle defense-associated secondary metabolites than trees from other ecosystems. Thus, trees from areas likely experiencing more frequent foliar disease outbreaks, due to a greater chance of historical outbreaks and inoculum build-up, evolved greater amounts of defense compounds in their needles than trees from less disease-prone regions. No such pattern was observed between bark diseases and bark compounds. In additional to other factors, pine provenances with greater foliar levels of these defense-associated compounds should be preferred seed sources for replanting forests in areas in which foliar disease is expected to be a factor affecting growth.