Local and systemic induction of JA-associated chemical defenses and resistance to western flower thrips in Chrysanthemum are spatially variable and dependent on the site of the JA application. Plants have evolved numerous inducible defense traits to resist or tolerate herbivory, which can be activated locally at the site of the damage, or systemically through the whole plant. Here we investigated how activation of local and systemic chemical responses upon exogenous application of the phytohormone jasmonic acid (JA) varies along the plant canopy in Chrysanthemum, and how these responses correlate with resistance to thrips. Our results showed that JA application reduced thrips damage per plant when applied to all the plant leaves or when locally applied to apical leaves, but not when only basal leaves were locally treated. Local application of JA to apical leaves resulted in a strong reduction in thrips damage in new leaves developed after the JA application. Yet, activation of a JA-associated defensive protein marker, polyphenol oxidase, was only locally induced. Untargeted metabolomic analysis further showed that JA increased the concentrations of sugars, phenylpropanoids, flavonoids and some amino acids in locally induced basal and apical leaves. However, local application of JA to basal leaves marginally affected the metabolomic profiles of systemic non-treated apical leaves, and vice versa. Our results suggest that JA-mediated activation of systemic chemical defense responses is spatially variable and depends on the site of the application of the hormone in Chrysanthemum.

中文翻译：

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茉莉酸相关化学防御对菊花中西部花蓟马的位点依赖性诱导

菊花中与 JA 相关的化学防御和对西方花蓟马的抗性的局部和全身诱导在空间上是可变的，并且取决于 JA 应用的位点。植物已经进化出许多可诱导的防御特性来抵抗或耐受食草动物，它们可以在损伤部位局部激活，也可以通过整个植物全身激活。在这里，我们研究了外源施用植物激素茉莉酸 (JA) 后局部和全身化学反应的激活如何沿着菊花的植物冠层变化，以及这些反应如何与对蓟马的抗性相关联。我们的研究结果表明，当施用于所有植物叶子或局部施用于顶端叶时，JA 应用减少了每株植物的蓟马损伤，但仅在基部叶进行局部处理时则不然。将 JA 局部施用于顶端叶可大大减少施用 JA 后新叶中蓟马的损害。然而，JA 相关防御蛋白标记物多酚氧化酶的激活只是局部诱导的。非靶向代谢组学分析进一步表明，JA 增加了局部诱导的基部和顶端叶中糖、苯丙素、类黄酮和一些氨基酸的浓度。然而，将 JA 局部应用到基生叶对系统性未处理顶端叶的代谢组学特征有轻微影响，反之亦然。我们的研究结果表明，JA 介导的全身化学防御反应的激活在空间上是可变的，并且取决于菊花中激素的应用位点。