School of Forestry, Northern Arizona University, Box 15018, Flagstaff, AZ 86011, USA.
Tree Physiol. 2011 Apr;31(4):428-37. doi: 10.1093/treephys/tpr025.
Tree defense against bark beetles (Curculionidae: Scolytinae) and their associated fungi generally comprises some combination of constitutive (primary) and induced (secondary) defenses. In pines, the primary constitutive defense against bark beetles consists of preformed resin stored in resin ducts. Induced defenses at the wound site (point of beetle entry) in pines may consist of an increase in resin flow and necrotic lesion formation. The quantity and quality of both induced and constitutive defenses can vary by species and season. The inducible defense response in ponderosa pine is not well understood. Our study examined the inducible defense response in ponderosa pine using traumatic mechanical wounding, and wounding with and without fungal inoculations with two different bark beetle-associated fungi (Ophiostoma minus and Grosmannia clavigera). Resin flow did not significantly increase in response to any treatment. In addition, necrotic lesion formation on the bole after fungal inoculation was minimal. Stand thinning, which has been shown to increase water availability, had no, or inconsistent, effects on inducible tree defense. Our results suggest that ponderosa pine bole defense against bark beetles and their associated fungi is primarily constitutive and not induced.
树木对树皮甲虫（象甲科：小蠹科）及其相关真菌的防御通常包括组成性（初级）和诱导性（次级）防御的某种组合。在松树上，对树皮甲虫的主要组成性防御包括储存在树脂道中的预成型树脂。在松树的伤口部位（甲虫进入的部位）可能会产生诱导性防御，包括树脂流量增加和坏死病变形成。诱导和组成性防御的数量和质量因物种和季节而异。对黄杉的诱导性防御反应还不太清楚。我们的研究使用创伤性机械损伤以及用和不用两种不同的与树皮甲虫相关的真菌（拟盘多毛孢菌和格氏密衣囊菌）进行的接种来研究黄杉的诱导性防御反应。树脂流量没有因任何处理而显著增加。此外，真菌接种后在树干上形成的坏死病变很小。已显示出增加水分供应的疏伐对诱导性树木防御没有影响，或者影响不一致。我们的结果表明，黄杉对树皮甲虫及其相关真菌的树干防御主要是组成性的，而不是诱导性的。
