Mauch-Mani B., Slusarenko A. J.
Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
Plant Cell. 1996 Feb;8(2):203-212. doi: 10.1105/tpc.8.2.203.
Arabidopsis ecotype Columbia (Col-0) seedlings, transformed with a phenylalanine ammonia-lyase 1 promoter (PAL1)-[beta]-glucuronidase (GUS) reporter construct, were inoculated with virulent and avirulent isolates of Peronospora parasitica. The PAL1 promoter was constitutively active in the light in vascular tissue but was induced only in the vicinity of fungal structures in the incompatible interaction. A double-staining procedure was developed to distinguish between GUS activity and fungal structures. The PAL1 promoter was activated in cells undergoing lignification in the incompatible interaction in response to the pathogen. Pretreatment of the seedlings with 2-aminoindan-2-phosphonic acid (AIP), a highly specific PAL inhibitor, made the plants completely susceptible. Lignification was suppressed after AIP treatment, and surprisingly, pathogen-induced PAL1 promoter activity could not be detected. Treatment of the seedlings with 2-hydroxyphenylaminosulphinyl acetic acid (1,1-dimethyl ester) (OH-PAS), a cinnamyl alcohol dehydrogenase inhibitor specific for the lignification pathway, also caused a shift toward susceptibility, but the effect was not as pronounced as it was with AIP. Significantly, although OH-PAS suppressed pathogen-induced lignification, it did not suppress pathogen-induced PAL1 promoter activation. Salicylic acid (SA), supplied to AIP-treated plants, restored resistance and both pathogen-induced lignification and activation of the PAL1 promoter. Endogenous SA levels increased significantly in the incompatible but not in the compatible combination, and this increase was suppressed by AIP but not by OH-PAS. These results provide evidence of the central role of SA in genetically determined plant disease resistance and show that lignification per se, although providing a component of the resistance mechanism, is not the deciding factor between resistance and susceptibility.
用苯丙氨酸解氨酶1启动子（PAL1）-[β]-葡萄糖醛酸酶（GUS）报告基因构建体转化的拟南芥生态型哥伦比亚（Col-0）幼苗，接种了寄生霜霉的强毒株和无毒株。PAL1启动子在维管组织中光照下组成型活跃，但仅在不亲和互作中真菌结构附近被诱导。开发了一种双重染色程序以区分GUS活性和真菌结构。在不亲和互作中，PAL1启动子在响应病原体而进行木质化的细胞中被激活。用2-氨基茚-2-膦酸（AIP）（一种高度特异性的PAL抑制剂）预处理幼苗，使植物完全感病。AIP处理后木质化受到抑制，令人惊讶的是，未检测到病原体诱导的PAL1启动子活性。用2-羟基苯氨基亚磺酰基乙酸（1,1-二甲基酯）（OH-PAS）（一种对木质化途径特异的肉桂醇脱氢酶抑制剂）处理幼苗，也导致向感病性转变，但效果不如AIP明显。值得注意的是，尽管OH-PAS抑制了病原体诱导的木质化，但它并未抑制病原体诱导的PAL1启动子激活。向AIP处理的植物供应水杨酸（SA），恢复了抗性以及病原体诱导的木质化和PAL1启动子的激活。在不亲和组合中内源性SA水平显著增加，而在亲和组合中未增加，并且这种增加被AIP抑制，但未被OH-PAS抑制。这些结果提供了SA在遗传决定的植物抗病性中核心作用的证据，并表明木质化本身虽然是抗性机制的一个组成部分，但不是抗性和感病性之间的决定性因素。
