Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short-lived model plants such as Arabidopsis, but little is known about this phenomenon in long-lived plants like spruce. We compared the effects of pretreatment with sublethal fungal inoculations or application of the phytohormone methyl jasmonate (MeJA) on the resistance of 48-year-old Norway spruce (Picea abies) trees to mass attack by a tree-killing bark beetle beginning 35 days later. Bark beetles heavily infested and killed untreated trees but largely avoided fungus-inoculated trees and MeJA-treated trees. Quantification of defensive terpenes at the time of bark beetle attack showed fungal inoculation induced 91-fold higher terpene concentrations compared with untreated trees, whereas application of MeJA did not significantly increase terpenes. These results indicate that resistance in fungus-inoculated trees is a result of direct induction of defenses, whereas resistance in MeJA-treated trees is due to defense priming. This work extends our knowledge of defense priming from model plants to an ecologically important tree species.

中文翻译：

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诱导性防御的启动可保护挪威云杉免受杀死树木的树皮甲虫的侵害。

植物可以形成被称为防御启动的免疫记忆，通过暴露于启动刺激可以更快或更强地响应害虫和病原体的后续攻击。这种可诱导防御的启动可提供增强的保护并降低防御的分配成本。对于诸如拟南芥（Arabidopsis）之类的短命模型植物，防御启动已被广泛研究，但是对于长寿命植物（如云杉），这种现象知之甚少。我们比较了用致死性真菌接种或应用植物激素茉莉酮酸甲酯（MeJA）预处理对48岁挪威云杉（Picea abies）树木在35天后开始对杀树皮甲虫的大规模侵袭的抵抗力的影响。 。树皮甲虫大量出没并杀死了未经处理的树木，但在很大程度上避免了接种真菌的树木和经过MeJA处理的树木。树皮甲虫攻击时防御性萜烯的定量显示，与未处理的树木相比，真菌接种诱导的萜烯浓度高91倍，而MeJA的施用并未显着增加萜烯。这些结果表明，接种真菌的树木中的抗性是防御的直接诱导的结果，而经MeJA处理的树木中的抗性是由于防御启动而引起的。这项工作将我们的防御启动知识从模型植物扩展到了具有生态重要性的树种。这些结果表明，接种真菌的树的抗性是防御的直接诱导的结果，而经MeJA处理的树中的抗性是由于防御启动引起的。这项工作将我们的防御启动知识从模型植物扩展到了具有生态重要性的树种。这些结果表明，接种真菌的树的抗性是防御的直接诱导的结果，而经MeJA处理的树中的抗性是由于防御启动引起的。这项工作将我们的防御启动知识从模型植物扩展到了具有生态重要性的树种。