Choi D., Bostock R. M.
Department of Plant Pathology, University of California, Davis, California 95616.
Plant Physiol. 1994 Apr;104(4):1237-1244. doi: 10.1104/pp.104.4.1237.
A series of inhibitors were tested to determine the participation of de novo protein synthesis, protein kinase activity, extracellular Ca2+, and lipoxygenase activity in arachidonic acid elicitation of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene expression and sesquiterpene phytoalexin biosynthesis in potato (Solanum tuberosum L. cv Kennebec). Gene-specific probes were used to discriminate effects on the expression of two HMGR genes (hmg1 and hmg2) that respond differentially in tuber tissue following wounding or elicitor treatment. Inhibition of protein synthesis with cycloheximide completely blocked arachidonate-induced hypersensitive necrosis and browning, including HMGR gene induction and phytoalexin accumulation. This suggests that proteins necessary for coupling arachidonic acid reception to HMGR mRNA accumulation are either rapidly turned over or not present constitutively and are induced following elicitor treatment. Staurosporin, a potent inhibitor of protein kinases, and ethyleneglycol-bis([beta]-aminoethyl ether)-N,N[prime]-tetraacetic acid, a Ca2+ chelator, inhibited arachidonate-induction of hmg2 gene expression and phytoalexin accumulation but did not inhibit the wound-induced expression of hmg1. However, staurosporin inhibited arachidonate's suppression of hmg1 gene expression. Eicosatetraynoic acid, a lipoxygenase inhibitor that suppresses elicitor-induced phytoalexin accumulation, also inhibited arachidonate's suppression of hmg1 and induction of hmg2. The results indicate that arachidonate's suppression of hmg1 and activation of hmg2 depend on a common intermediate or set of intermediates whose generation is sensitive to the inhibitors tested.
测试了一系列抑制剂，以确定从头合成蛋白质、蛋白激酶活性、细胞外钙离子和脂氧合酶活性在花生四烯酸引发马铃薯（Solanum tuberosum L. cv Kennebec）中3-羟基-3-甲基戊二酰辅酶A还原酶（HMGR）基因表达和倍半萜植保素生物合成过程中的作用。使用基因特异性探针来区分对两个HMGR基因（hmg1和hmg2）表达的影响，这两个基因在受伤或激发子处理后的块茎组织中反应不同。用环己酰亚胺抑制蛋白质合成完全阻断了花生四烯酸诱导的过敏坏死和褐变，包括HMGR基因诱导和植保素积累。这表明将花生四烯酸受体与HMGR mRNA积累偶联所需的蛋白质要么快速周转，要么不是组成性存在，而是在激发子处理后被诱导。星形孢菌素是一种有效的蛋白激酶抑制剂，乙二醇双（β-氨基乙基醚）-N,N'-四乙酸是一种钙离子螯合剂，它们抑制了花生四烯酸对hmg2基因表达和植保素积累的诱导，但没有抑制伤口诱导的hmg1表达。然而，星形孢菌素抑制了花生四烯酸对hmg1基因表达的抑制作用。二十碳四炔酸是一种脂氧合酶抑制剂，可抑制激发子诱导的植保素积累，它也抑制了花生四烯酸对hmg!的抑制作用和对hmg2的诱导作用。结果表明，花生四烯酸对hmg1的抑制作用和对hmg2的激活作用依赖于一个共同的中间体或一组中间体，其生成对所测试的抑制剂敏感。
