salicylate-mediated interactions between pathogens and insects

We tested predictions about the relative effect of jasmonate and salicylate pathways and how they mediate interactions between pathogens and herbivores. We employed two pathogens of tomato, Pseudomonas syringae (Pst) and Tobacco mosaic virus (TMV), that are known to elicit distinct components of the two pathways, and address the consequences of their induction for resistance in wild-type and salicylate-deficient transgenic plants in field experiments. We report that Pst infection induced jasmonic acid, proteinase inhibitors (PIs), and reduced Spodoptera exigua growth on wild-type and salicylate-deficient plants. Pst and TMV both induced salicylic acid in wild-type but not salicylate-deficient plants. Although TMV did not affect jasmonic acid or PIs, infection increased caterpillar growth on wild type plants, but not on salicylate-deficient plants. Aphid population growth was higher on salicylate-deficient compared to wild-type plants, and lower on salicylate-induced plants compared to controls. Natural aphid colonization was reduced on TMV infected wild-types, but not on salicylate-deficient plants.本研究旨在验证关于茉莉酸（jasmonate）与水杨酸（salicylate）通路的相对效应，及其介导病原菌与植食性昆虫互作机制的相关预测。我们选用两种已知可特异性激活上述两条通路不同组分的番茄病原菌——丁香假单胞菌（Pseudomonas syringae，Pst）与烟草花叶病毒（Tobacco mosaic virus，TMV），通过田间试验探究其诱导处理对野生型及水杨酸缺陷型转基因植株抗病性的影响。本研究结果显示，丁香假单胞菌侵染可在野生型与水杨酸缺陷型植株中诱导茉莉酸与蛋白酶抑制剂（proteinase inhibitors，PIs）的积累，并抑制甜菜夜蛾（Spodoptera exigua）的生长。丁香假单胞菌与烟草花叶病毒均可在野生型植株中诱导水杨酸积累，但无法在水杨酸缺陷型植株中触发该诱导过程。尽管烟草花叶病毒未对茉莉酸或蛋白酶抑制剂的水平产生显著影响，但其侵染可提升野生型植株上鳞翅目幼虫的生长速率，而对水杨酸缺陷型植株无此效应。相较于野生型植株，水杨酸缺陷型植株上的蚜虫种群增长更快；经水杨酸诱导的植株，其蚜虫种群增长则显著低于对照组。烟草花叶病毒侵染的野生型植株的自然蚜虫定殖率显著降低，但该抑制效应并未出现在水杨酸缺陷型植株中。