Department of Plant Pathology, University of California at Davis, Davis CA, USA.
Front Plant Sci. 2013 May 6;4:116. doi: 10.3389/fpls.2013.00116. eCollection 2013.
Plant activators are chemicals that induce disease resistance. The phytohormone salicylic acid (SA) is a crucial signal for systemic acquired resistance (SAR), and SA-mediated resistance is a target of several commercial plant activators, including Actigard (1,2,3-benzothiadiazole-7-thiocarboxylic acid-S-methyl-ester, BTH) and Tiadinil [N-(3-chloro-4-methylphenyl)-4-methyl-1,2,3-thiadiazole-5-carboxamide, TDL]. BTH and TDL were examined for their impact on abscisic acid (ABA)-mediated, salt-induced disease predisposition in tomato seedlings. A brief episode of salt stress to roots significantly increased the severity of disease caused by Pseudomonas syringae pv. tomato (Pst) and Phytophthora capsici relative to non-stressed plants. Root treatment with TDL induced resistance to Pst in leaves and provided protection in both non-stressed and salt-stressed seedlings in wild-type and highly susceptible NahG plants. Non-stressed and salt-stressed ABA-deficient sitiens mutants were highly resistant to Pst. Neither TDL nor BTH induced resistance to root infection by Phytophthora capsici, nor did they moderate the salt-induced increment in disease severity. Root treatment with these plant activators increased the levels of ABA in roots and shoots similar to levels observed in salt-stressed plants. The results indicate that SAR activators can protect tomato plants from bacterial speck disease under predisposing salt stress, and suggest that some SA-mediated defense responses function sufficiently in plants with elevated levels of ABA.
植物激活剂是诱导抗病性的化学物质。植物激素水杨酸（SA）是系统获得性抗性（SAR）的关键信号，SA 介导的抗性是几种商业植物激活剂的靶标，包括 Actigard（1,2,3-苯并噻二唑-7-硫代羧酸-S-甲酯，BTH）和 Tiadinil[N-(3-氯-4-甲基苯基）-4-甲基-1,2,3-噻二唑-5-甲酰胺，TDL]。研究了 BTH 和 TDL 对番茄幼苗脱落酸（ABA）介导的盐诱导易感性疾病的影响。根系短暂的盐胁迫显著增加了相对于非胁迫植物的丁香假单胞菌 pv.番茄（Pst）和辣椒疫霉引起的疾病严重程度。TDL 对根的处理诱导了叶片中对 Pst 的抗性，并为非胁迫和盐胁迫下野生型和高度敏感的 NahG 植物中的幼苗提供了保护。非胁迫和盐胁迫下的 ABA 缺陷 sitiens 突变体对 Pst 具有高度抗性。TDL 和 BTH 既不能诱导对辣椒疫霉根侵染的抗性，也不能减轻盐诱导的疾病严重程度增加。这些植物激活剂对根的处理增加了根和地上部分的 ABA 水平，与盐胁迫下观察到的水平相似。结果表明，SAR 激活剂可以在易感盐胁迫的情况下保护番茄植物免受细菌性斑点病的侵害，并表明一些 SA 介导的防御反应在 ABA 水平升高的植物中足够发挥作用。
