Department of Renewable Resources, 442 Earth Sciences Building, University of Alberta, Edmonton, AB, Canada T6G 2E3.
Tree Physiol. 2012 Aug;32(8):946-57. doi: 10.1093/treephys/tps047. Epub 2012 Jun 1.
Coniferous trees have both constitutive and inducible defences that deter or kill herbivores and pathogens. We investigated constitutive and induced monoterpene responses of jack pine (Pinus banksiana Lamb.) to a number of damage types: a fungal associate of the mountain pine beetle (Dendroctonus ponderosae Hopkins), Grosmannia clavigera (Robinson-Jeffrey & R.W. Davidson); two phytohormones, methyl jasmonate (MJ) and methyl salicylate (MS); simulated herbivory; and mechanical wounding. We only included the fungal, MJ and mechanical wounding treatments in the field experiments while all treatments were part of the greenhouse studies. We focused on both constitutive and induced responses between juvenile and mature jack pine trees and differences in defences between phloem and needles. We found that phytohormone applications and fungal inoculation resulted in the greatest increase in monoterpenes in both juvenile and mature trees. Additionally, damage types differentially affected the proportions of individual monoterpenes: MJ-treated mature trees had higher myrcene and β-pinene than fungal-inoculated mature trees, while needles of juveniles inoculated with the fungus contained higher limonene than MJ- or MS-treated juveniles. Although the constitutive monoterpenes were higher in the phloem of juveniles than mature jack pine trees, the phloem of mature trees had a much higher magnitude of induction. Further, induced monoterpene concentrations in juveniles were higher in phloem than in needles. There was no difference in monoterpene concentration between phytohormone applications and G. clavigera inoculation in mature trees, while in juvenile trees MJ was different from both G. clavigera and simulated herbivory in needle monoterpenes, but there was no difference between phytohormone applications and simulated herbivory in the phloem.
针叶树具有组成型和诱导型防御机制，可以阻止或杀死食草动物和病原体。我们研究了短叶松（Pinus banksiana Lamb.）对多种损伤类型的组成型和诱导型单萜响应：一种与山松甲虫（Dendroctonus ponderosae Hopkins）相关的真菌， Grosmannia clavigera（Robinson-Jeffrey & R.W. Davidson）；两种植物激素，茉莉酸甲酯（MJ）和水杨酸甲酯（MS）；模拟的食草动物侵害；以及机械性损伤。我们仅在田间实验中包括真菌、MJ 和机械损伤处理，而所有处理均为温室研究的一部分。我们专注于幼树和成熟短叶松之间的组成型和诱导型反应以及韧皮部和针叶之间防御机制的差异。我们发现，植物激素处理和真菌接种导致幼树和成熟树中单萜的最大增加。此外，损伤类型对个体单萜的比例有不同的影响：用 MJ 处理的成熟树中的月桂烯和β-蒎烯高于用真菌接种的成熟树，而真菌接种的幼树的针叶中的柠檬烯高于用 MJ 或 MS 处理的幼树。尽管幼树韧皮部中的组成型单萜含量高于成熟短叶松，但成熟树韧皮部的诱导程度要高得多。此外，幼树诱导的单萜浓度在韧皮部中高于针叶。在成熟树中，植物激素处理和 Grosmannia clavigera 接种之间的单萜浓度没有差异，而在幼树中，MJ 与 Grosmannia clavigera 和模拟食草动物侵害在针叶中单萜方面不同，但植物激素处理和模拟食草动物侵害在韧皮部中单萜方面没有差异。
