[Book Chapter] Salicylic acid and aromatic monoamines induce generation of active oxygen species leading to increase in cytosolic Ca2+ concentration in tobacco suspension culture. (original) (raw)
Related papers
Plant cell reports, 2003
Extracellularly secreted plant peroxidases (POXs) are considered to catalyze the generation of reactive oxygen species (ROS) coupled to oxidation of plant hormone indole-3-acetic acid (IAA) and defense-related compounds salicylic acid (SA), aromatic monoamines (AMAs) and chitooligosaccharides (COSs). This review article consists of two parts, which describe H(2)O(2)-dependent and H(2)O(2)-independent mechanisms for ROS generation, respectively. Recent studies have shown that plant POXs oxidize SA, AMAs and COSs in the presence of H(2)O(2) via a conventional POX cycle, yielding the corresponding radical species, such as SA free radicals. These radical species may react with oxygen, and superoxide (O(2)(.-)) is produced. Through the series of reactions 2 moles of O(2)(.-) can be formed from 1 moles of H(2)O(2), thus leading to oxidative burst. It has been revealed that the ROS induced by SA, AMAs and COSs triggers the increase in cytosolic Ca(2+) concentration. Actually POXs transduce...
Extracellularly secreted plant peroxidases (POXs) are considered to catalyze the generation of reactive oxygen species (ROS) coupled to oxidation of plant hormone indole-3-acetic acid (IAA) and defenserelated compounds salicylic acid (SA), aromatic monoamines (AMAs) and chitooligosaccharides (COSs). This review article consists of two parts, which describe H2O2-dependent and H2O2-independent mechanisms for ROS generation, respectively. Recent studies have shown that plant POXs oxidize SA, AMAs and COSs in the presence of H2O2 via a conventional POX cycle, yielding the corresponding radical species, such as SA free radicals. These radical species may react with oxygen, and superoxide (O2·) is produced. Through the series of reactions 2 moles of O2· can be formed from 1 moles of H2O2, thus leading to oxidative burst. It has been revealed that the ROS induced by SA, AMAs and COSs triggers the increase in cytosolic Ca2+ concentration. Actually POXs transduce the extracellular signals into the redox signals that eventually stimulate the intracellular Ca2+ signaling required for induction of defense responses. On the other hand, IAA can react with oxygen and plant POXs in the absence of H2O2, by forming the ternary complex enzyme-IAA-O2, which readily dissociates into enzyme, IAA radicals and O2·. This article covers the recent reports showing that extracellularly produced hydroxy radicals derived from O2· mediate the IAAinduced cell elongation. Here a novel model for IAA signaling pathway mediated by extracellular ROS produced by cell-wall POXs is proposed. In addition, possible controls of the IAA-POX reactions by a fungal alkaloid are discussed.
that superoxide was converted to H 2 O 2. In addition, it was observed that superoxide dismutase-insensitive Extracellularly secreted peroxidases in cell suspension ESR signal of monodehydroascorbate radical was culture of tobacco (Nicotiana tabacum L. cv. Bright induced by SA both in the tobacco suspension culture Yellow-2, cell line BY-2) catalyse the salicylic acid (SA)-and HRP reaction mixture, suggesting that SA free dependent formation of active oxygen species (AOS) radicals, highly reactive against ascorbate, were which, in turn, triggers an increase in cytosolic Ca2+ formed by peroxidase-catalysed reactions. The forma-concentration. Addition of horseradish peroxidase tion of SA free radicals may lead to subsequent mono-(HRP) to tobacco cell suspension culture enhanced the valent reduction of O 2 to superoxide. SA-induced increase in cytosolic Ca2+ concentration, suggesting that HRP enhanced the production of AOS.
In the previous paper [Kawano et al. (2000a) Plant Cell Physiol. 41: 1251], we demonstrated that addition of phe-nylethylamine (PEA) and benzylamine can induce an immediate and transient burst of active oxygen species (AOS) in tobacco suspension culture. Detected AOS include H2O2 , superoxide anion and hydroxyl radicals. Use of several in-hibitors suggested the presence of monoamine oxidase-like H2O2-generating activity in the cellular soluble fraction. It was also suggested that peroxidase(s) or copper amine oxi-dase(s) are involved in the extracellular superoxide production as a consequence of H2O2 production. Since more than 85% of the PEA-dependent AOS generating activity was localized in the extracellular space (extracellular fluid + cell wall), extracellularly secreted enzymes, probably peroxi-dases, may largely contribute to the oxidative burst induced by PEA. The PEA-induced AOS generation was also observed in the horseradish peroxidase (HRP) reaction mixture, supporting the hypothesis that peroxidases cata-lyze the oxidation of PEA leading to AOS generation. In addition to AOS production, we observed that PEA induced an increase in monodehydroascorbate radicals (MDA) in the cell suspension culture and in HRP reaction mixture using electron spin resonance spectroscopy and the newly invented MDA reductase-coupled method. Here we report that MDA production is an indicator of peroxidase-mediated generation of PEA radical species in tobacco suspension culture.
The production of reactive oxygen species (ROS), such as superoxide radical (O 2 •-), hydroxyl radical (OH •) and hydrogen peroxide (H 2 O 2), in plants is a common event in metabolic and physiological processes. ROS are normally formed in photosynthesis and respiration by the chloroplast and mitochondrial electron transfer chains, respectively, and in metabolic reactions taking place in the peroxisomes. As these active oxygen species are destructive to cellular components such as lipids, nucleic acid and proteins, plant cells are equipped with non-enzymatic and enzymatic antioxidant defense systems comprising ascorbate, glutathione, phenols, catalases, super-oxide dismutases and peroxidases. Biotic and abiotic stress, such as salinity stress, excess of heavy metals, mechanical shock, UV light, exposure to ozone, water deficiency and pathogen attack, also increase ROS production. In the latter case the release of ROS, referred to as the " oxidative burst " , is one of the earliest responses activated following pathogen recognition and has been suggested to play a pivotal role in the integration and the coordination of the plant defense responses. In this review we summarize the current knowledge about ROS production and oxidative defense in plants. The role of ROS will be discussed in the frame of stress responses, with emphasis on the plant-pathogen interaction.