Kauss H, Fauth M, Merten A, Jeblick W
Fachbereich Biologie der Universitat, Postfach 3049, D-67653 Kaiserslautern, Germany.
Plant Physiol. 1999 Aug;120(4):1175-82. doi: 10.1104/pp.120.4.1175.
Hypocotyls from etiolated cucumber (Cucumis sativa L.) seedlings were gently abraded at their surface to allow permeation of elicitors. Segments from freshly abraded hypocotyls were only barely competent for H(2)O(2) elicitation with fungal elicitor or hydroxy fatty acids (classical cutin monomers). However, elicitation competence developed subsequent to abrasion, reaching an optimum after about 4 h. This process was potentiated in seedlings displaying acquired resistance to Colletotrichum lagenarium due to root pretreatment with 2,6-dichloroisonicotinic acid or a benzothiadiazole. Induction of competence depended on protein synthesis and could be effected not only by surface abrasion, but also by fungal spore germination on the epidermal surface or by rotating the seedlings in buffer. Inhibitor studies indicated that the inducible mechanism for H(2)O(2) production involves protein phosphorylation, Ca(2+) influx, and NAD(P)H oxidase. In contrast, a novel cucumber cutin monomer, dodecan-1-ol, also elicited H(2)O(2) in freshly abraded hypocotyls without previous competence induction. This finding suggests the presence of an additional H(2)O(2)-generating system that is constitutive. It is insensitive to inhibitors and has, in addition, a different specificity for alkanols. Thus, dodecan-1-ol might initiate defense before the inducible H(2)O(2)-generating system becomes effective.
将黄化黄瓜（Cucumis sativa L.）幼苗的下胚轴表面轻轻擦伤，以使激发子能够渗透。刚擦伤的下胚轴切段对真菌激发子或羟基脂肪酸（典型的角质单体）引发的H(2)O(2)反应能力很弱。然而，擦伤后反应能力逐渐增强，约4小时后达到最佳状态。在用2,6-二氯异烟酸或苯并噻二唑对根部进行预处理而表现出对炭疽菌获得性抗性的幼苗中，这一过程得到了增强。反应能力的诱导依赖于蛋白质合成，不仅可以通过表面擦伤实现，还可以通过表皮表面的真菌孢子萌发或在缓冲液中旋转幼苗来实现。抑制剂研究表明，H(2)O(2)产生的诱导机制涉及蛋白质磷酸化、Ca(2+)内流和NAD(P)H氧化酶。相比之下，一种新型黄瓜角质单体十二烷-1-醇，在未经预先诱导反应能力的新鲜擦伤下胚轴中也能引发H(2)O(2)。这一发现表明存在一个组成型的额外H(2)O(2)生成系统。它对抑制剂不敏感，此外，对链烷醇具有不同的特异性。因此，十二烷-1-醇可能在可诱导的H(2)O(2)生成系统生效之前就启动防御反应。
