Effects of Feeding Spodoptera littoralis on Lima Bean Leaves. III. Membrane Depolarization and Involvement of Hydrogen Peroxide

• Published in: Plant physiology (Bethesda) Vol. 140; no. 3; pp. 1022 - 1035
• Main Authors: Maffei, Massimo E., Mithöfer, Axel, Arimura, Gen-Ichiro, Uchtenhagen, Hannes, Bossi, Simone, Bertea, Cinzia M., Cucuzza, Laura Starvaggi, Novero, Mara, Volpe, Veronica, Quadro, Stefano, Boland, Wilhelm
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.03.2006; American Society of Plant Physiologists
• Subjects: Aequorin - metabolism; Animals; Biological and medical sciences; Calcium; Calcium - metabolism; Cell Membrane - metabolism; Cell physiology; Depolarization; Enzymes; Feeding Behavior; Free Radical Scavengers - metabolism; Fundamental and applied biological sciences. Psychology; Glycine max; Glycine max - cytology; Glycine max - genetics; Herbivores; Hydrogen; Hydrogen Peroxide - analysis; Hydrogen Peroxide - metabolism; Leaves; Lima; Medicin och hälsovetenskap; Membrane Potentials; Microscopy, Confocal; Models, Biological; Peroxides; Phaseolus - cytology; Phaseolus - metabolism; Phaseolus - physiology; Phaseolus lunatus; Plant cells; Plant Leaves - cytology; Plant Leaves - metabolism; Plant Leaves - physiology; Plant physiology and development; Plants; Plants Interacting with Other Organisms; Plants, Genetically Modified - metabolism; Plasma membrane and permeation; Reactive oxygen species; Reverse Transcriptase Polymerase Chain Reaction; Spodoptera - pathogenicity; Spodoptera littoralis; Superoxide Dismutase - metabolism; Intercellular space; Phaseolus lunatus; Enzyme; Superoxide dismutase; Plant leaf; Glycine max; Cell wall; Mitochondria; Leguminosae; Gene; Dicotyledones; Angiospermae; Peroxisome; Spermatophyta; Oxidoreductases; Membrane potential; Renilla-luciferin 2-monooxygenase
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.105.071993

In response to herbivore (Spodoptera littoralis) attack, lima bean (Phaseolus lunatus) leaves produced hydrogen peroxide (H₂O₂) in concentrations that were higher when compared to mechanically damaged (MD) leaves. Cellular and subcellular localization analyses revealed that H₂O₂ was mainly localized in MD and herbivore-wounded (HW) zones and spread throughout the veins and tissues. Preferentially, H₂O₂ was found in cell walls of spongy and mesophyll cells facing intercellular spaces, even though confocal laser scanning microscopy analyses also revealed the presence of H₂O₂ in mitochondria/peroxisomes. Increased gene and enzyme activations of superoxide dismutase after HW were in agreement with confocal laser scanning microscopy data. After MD, additional application of H₂O₂ prompted a transient transmembrane potential ($V_{\text{m}}$) depolarization, with a $V_{\text{m}}$ depolarization rate that was higher when compared to HW leaves. In transgenic soybean (Glycine max) suspension cells expressing the Ca²⁺-sensing aequorin system, increasing amounts of added H₂O₂ correlated with a higher cytosolic calcium ($[\text{Ca}^{2+}]_{\text{cyt}}$) concentration. In MD and HW leaves, H₂O₂ also triggered the increase of $[\text{Ca}^{2+}]_{\text{cyt}}$, but MD-elicited $[\text{Ca}^{2+}]_{\text{cyt}}$ increase was more pronounced when compared to HW leaves after addition of exogenous H₂O₂. The results clearly indicate that $V_{\text{m}}$ depolarization caused by HW makes the membrane potential more positive and reduces the ability of lima bean leaves to react to signaling molecules.