Phytopathology. 1999 Sep;89(9):722-7. doi: 10.1094/PHYTO.1999.89.9.722.
ABSTRACT Alternaria solani is the causal agent of early blight disease in tomato and is responsible for significant economic losses sustained by tomato producers each year. Because salicylic acid (SA) is an important signal molecule that plays a critical role in plant defense against pathogen invasion, we investigated if the exogenous application of SA would activate systemic acquired resistance (SAR) against A. solani in tomato leaves. The addition of 200 muM SA to the root system significantly increased the endogenous SA content of leaves. Free SA levels increased 65-fold over basal levels to 5.85 mug g(-1) fresh weight (FW) after 48 h. This level of SA had no visible phytotoxic effects. Total SA content (free SA + SA-glucose conjugate) increased to 108 mug g(-1) FW after 48 h. Concomitant with elevated SA levels, expression of the tomato pathogenesis-related (PR)-1B gene was strongly induced within 24 h of the addition of 200 muM SA. PR-1B expression was still evident after 48 h; however, PR-1B induction was not observed in plants not receiving SA treatment. Challenge inoculation of SA-treated tomato plants using conidia of A. solani resulted in 83% fewer lesions per leaf and a 77% reduction in blighted leaf area as compared with control plants not receiving SA. Our data indicate that root feeding 200 muM SA to tomato plants can (i) significantly elevate foliar SA levels, (ii) induce PR-1B gene expression, and (iii) activate SAR that is effective against A. solani.
摘要链格孢菌是番茄早疫病的病原菌，每年都会给番茄种植者造成巨大的经济损失。由于水杨酸（SA）是一种重要的信号分子，在植物抵御病原体入侵的过程中起着关键作用，我们研究了外源施用 SA 是否会激活番茄叶片对链格孢菌的系统获得性抗性（SAR）。将 200 μM SA 添加到根系中，可显著增加叶片中的内源 SA 含量。48 小时后，游离 SA 水平比基础水平增加了 65 倍，达到 5.85 μg g(-1)鲜重（FW）。这种水平的 SA 没有明显的植物毒性作用。48 小时后，SA 总量（游离 SA + SA-葡萄糖缀合物）增加到 108 μg g(-1)FW。与 SA 水平升高同时，番茄病程相关（PR）-1B 基因的表达在添加 200 μM SA 后 24 小时内被强烈诱导。48 小时后仍能观察到 PR-1B 的诱导，但在未接受 SA 处理的植物中未观察到 PR-1B 的诱导。用链格孢菌的分生孢子对接受 SA 处理的番茄植株进行接种挑战，与未接受 SA 处理的对照植株相比，每叶的病斑数减少了 83%，病叶面积减少了 77%。我们的数据表明，用 200 μM SA 对番茄植株进行根部灌根可以（i）显著提高叶片 SA 水平，（ii）诱导 PR-1B 基因表达，以及（iii）激活对链格孢菌有效的 SAR。
