Import of polyphenol oxidase by chloroplasts is enhanced by methyl jasmonate

• Published in: Planta 2004-07, Vol.219 (3), p.412-419
• Main Authors: Koussevitzky, S, Ne'eman, E, Harel, E
• Format: Article
• Language: English
• Subjects: Acetates - pharmacology; Agronomy. Soil science and plant productions; Amino Acid Sequence; amino acid sequences; Biological and medical sciences; Biological Transport, Active - drug effects; Catechol Oxidase - genetics; Catechol Oxidase - metabolism; Chloroplasts; Chloroplasts - drug effects; Chloroplasts - metabolism; Cyclopentanes - pharmacology; Cystatins - genetics; Cystatins - metabolism; Economic plant physiology; Enzyme Precursors - metabolism; Enzymes; Ethylenes - pharmacology; fractionation; Fundamental and applied biological sciences. Psychology; Imports; laccase; methyl jasmonate; Molecular Sequence Data; monophenol monooxygenase; multicystatin; Nutrition. Photosynthesis. Respiration. Metabolism; Oxidases; Oxylipins; Peas; Pisum sativum; Pisum sativum - drug effects; Pisum sativum - genetics; Pisum sativum - metabolism; plant proteins; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Plastids; Polyphenols; protein binding; Protein precursors; Protein transport; proteinase inhibitors; signal transduction; Solanum lycopersicum - drug effects; Solanum lycopersicum - genetics; Solanum lycopersicum - metabolism; Solanum lycopersicum var. lycopersicum; Thylakoids; Thylakoids - drug effects; Thylakoids - metabolism; Tomatoes; Translocation; vegetable crops
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-004-1240-7

Polyphenol oxidase (PPO; EC 1.10.3.2 or EC 1.14.18.1) takes part in the response of tomato plants (Lycopersicon esculentum Mill.) to wounding and herbivore attack, mediated by the octadecanoid wound-signaling pathway. Wounding and methyl jasmonate (MeJA) induce expression of ppo genes and markedly increase the level of the enzyme. We report that pretreatment with MeJA also markedly increased the ability of isolated tomato chloroplasts to import and process PPO precursors (pPPO). Pea (Pisum sativum L.) chloroplasts showed no such response. Wounding or ethylene alone was ineffective but ethylene was synergistic with MeJA. Treatment with MeJA conferred a strong binding of pPPO, or its processing intermediate, to thylakoids and subsequent translocation into the lumen and processing to the mature protein. The effect on PPO import and translocation was evident after 8-16 h exposure to MeJA. Membrane-bound pPPO was cross-linked to a proteinaceous component of the thylakoid translocation apparatus, apparently induced by MeJA. The import and processing of other nuclear-encoded thylakoid proteins were not affected by MeJA in tomato. A 90-kDa protein that co-fractionated with thylakoids was induced along with the increase in competence for PPO import, and was identified as the proteinase-inhibitor multicystatin. It is concluded that the 90-kDa protein observed is part of the MeJA-induced defense response of tomato, not a component of the thylakoid translocation apparatus.