Competence for Elicitation of H₂O₂ in Hypocotyls of Cucumber Is Induced by Breaching the Cuticle and Is Enhanced by Salicylic Acid

• Published in: Plant physiology (Bethesda) Vol. 110; no. 2; pp. 347 - 354
• Main Authors: Markus Fauth, Axel Merten, Hahn, Michael G., Wolfgang Jeblick, Kauss, Heinrich
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.02.1996
• Subjects: Abrasion; Animal cuticle; Biological and medical sciences; Cucumbers; Epidermal cells; Fundamental and applied biological sciences. Psychology; Hypocotyls; Metabolism; Metabolism. Physicochemical requirements; Parsley; Plant cuticle; Plant physiology and development; Plant-Microbe and Plant-Insect Interactions; Plants; Seedlings; Soybeans; Abrasion; Salicylic acid; Plant pathogen; Cucurbitaceae; Host agent relation; Cuticle; Biosynthesis; Cucumis sativus; Hydrogen Peroxides; Fungi; Colletotrichum lagenarium; Hypocotyl; Vegetable crop; Protein synthesis; Dicotyledones; Angiospermae; Spermatophyta; Elicitation; Fungi Imperfecti; Thallophyta
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.110.2.347

To study H2O2 production, the epidermal surfaces of hypocotyl segments from etiolated seedlings of cucumber (Cucumis sativus L.) were gently abraded. Freshly abraded segments were not constitutively competent for rapid H2O2 elicitation. This capacity developed subsequent to abrasion in a time-dependent process that was greatly enhanced in segments exhibiting an acquired resistance to penetration of their epidermal cell walls by Colletotrichum lagenarium, because of root pretreatment of the respective seedlings with 2,6-dichloroisonicotinic acid. When this compound or salicylic acid was applied to abraded segments, it also greatly enhanced the induction of competence for H2O2 elicitation. This process was fully inhibited by 5 μM cycloheximide or 200 μM puromycin, suggesting a requirement for translational protein synthesis. Both a crude elicitor preparation and a partially purified oligoglucan mixture from Phytophthora sojae also induced, in addition to H2O2 production, a refractory state, which explains the transient nature of H2O2 elicitation. Taken together, these results suggest that the cucumber hypocotyl epidermis becomes conditioned for competence to produce H2O2 in response to elicitors by a stimulus resulting from breaching the cuticle and/or cutting segments. This conditioning process is associated with protein synthesis and is greatly enhanced when substances able to induce systemic acquired resistance are present in the tissue.