In response to various stimuli, plants acquire resistance against pests and/or pathogens. Such acquired or induced resistance allows plants to rapidly adapt to their environment. Spraying the bark of mature Norway spruce (Picea abies ) trees with the phytohormone methyl jasmonate (MeJA) enhances resistance to tree‐killing bark beetles and their associated phytopathogenic fungi. Analysis of spruce chemical defenses and beetle colonization success suggests that MeJA treatment both directly induces immune responses and primes inducible defenses for a faster and stronger response to subsequent beetle attack. We used metabolite and transcriptome profiling to explore the mechanisms underlying MeJA‐induced resistance in Norway spruce. We demonstrated that MeJA treatment caused substantial changes in the bark transcriptional response to a triggering stress (mechanical wounding). Profiling of mRNA expression showed a suite of spruce inducible defenses are primed following MeJA treatment. Although monoterpenes and diterpene resin acids increased more rapidly after wounding in MeJA‐treated than control bark, expression of their biosynthesis genes did not. We suggest that priming of inducible defenses is part of a complex mixture of defense responses that underpins the increased resistance against bark beetle colonization observed in Norway spruce. This study provides the most detailed insights yet into the mechanisms underlying induced resistance in a long‐lived gymnosperm.

中文翻译：

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挪威云杉茉莉酸甲酯诱导的抗性的分子基础。

响应各种刺激，植物获得对害虫和/或病原体的抗性。这种获得或诱导的抗性允许植物快速适应其环境。喷洒成熟的挪威云杉的树皮（Picea abies）含有茉莉酮酸甲酯（MeJA）的树木增强了对杀死树木的树皮甲虫及其相关植物致病真菌的抵抗力。对云杉化学防御和甲虫定植成功的分析表明，MeJA处理既可以直接诱导免疫反应，又可以引发可诱导的防御，从而对随后的甲虫攻击有更快，更强的反应。我们使用代谢物和转录组图谱研究了挪威云杉中MeJA诱导的耐药性的潜在机制。我们证明了MeJA处理引起了对树皮转录反应的实质性变化，从而触发了应激（机械性损伤）。对mRNA表达谱的分析表明，在MeJA处理后引发了一系列云杉诱导防御。尽管在MeJA处理后，单萜和二萜树脂酸在受伤后比对照树皮增长更快，但其生物合成基因的表达却没有。我们建议引发诱导防御是防御反应复杂混合物的一部分，该防御反应增强了对挪威云杉中对树皮甲虫定植的抵抗力的增强。这项研究为长寿命裸子植物的诱导抗性机理提供了最详细的见解。