Production and diffusion of chloroplastic H₂O₂ and its implication to signalling

• Published in: Journal of experimental botany Vol. 61; no. 13; pp. 3577 - 3587
• Main Authors: Mubarakshina, Maria M, Ivanov, Boris N, Naydov, Ilya A, Hillier, Warwick, Badger, Murray R, Krieger-Liszkay, Anja
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.08.2010
• Subjects: antioxidants; Arabidopsis - metabolism; Arabidopsis - physiology; cell membranes; chloroplasts; Chloroplasts - metabolism; Diffusion; electron paramagnetic resonance spectroscopy; Electron Spin Resonance Spectroscopy; electron transfer; fluorescent dyes; hydrogen peroxide; Hydrogen Peroxide - metabolism; light intensity; photosynthesis; Photosynthesis - physiology; Plant Leaves - metabolism; reactive oxygen species; Signal Transduction; Spinacia oleracea - metabolism; Spinacia oleracea - physiology; Thylakoids - metabolism
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erq171

Hydrogen peroxide (H₂O₂) is recognized as an important signalling molecule. There are two important aspects to this function: H₂O₂ production and its diffusion to its sites of action. The production of H₂O₂ by photosynthetic electron transport and its ability to diffuse through the chloroplast envelope membranes has been investigated using spin trapping electron paramagnetic resonance spectroscopy and H₂O₂-sensitive fluorescence dyes. It was found that, even at low light intensity, a portion of H₂O₂ produced inside the chloroplasts can leave the chloroplasts thus escaping the effective antioxidant systems located inside the chloroplast. The production of H₂O₂ by chloroplasts and the appearance of H₂O₂ outside chloroplasts increased with increasing light intensity and time of illumination. The amount of H₂O₂ that can be detected outside the chloroplasts has been shown to be up to 5% of the total H₂O₂ produced inside the chloroplasts at high light intensities. The fact that H₂O₂ produced by chloroplasts can be detected outside these organelles is an important finding in terms of understanding how chloroplastic H₂O₂ can serve as a signal molecule.