Hydrogen-peroxide-scavenging systems within pea chloroplasts

Abstract

The subcellular distribution of ascorbate peroxidase and glutathione reductase (EC 1.6.4.2) in pea leaves was compared with that of organelle markers. Enzyme distribution was found to be similar to that of the chloroplast enzyme NADPH-glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13). Isolated chloroplasts showed a close correlation between intactness and the percentage of enzyme activity recovered. Chloroplasts of 85% intactness were found to contain a high proportion of leaf dehydroascorbate reductase activity (EC 1.8.5.1), 10% of leaf glutathione and 30% of leaf ascorbate. These results are discussed in relation to the potential role of chloroplast antioxidant systems in plant resistance to environmental and other stress conditions.

Comparison of Susceptibility to Photoinhibition and Energy Partitioning of Absorbed Light in Photosystem II in Flag Leaves of Two Rice (Oryza sativaL.) Cultivars that Differ in Their Responses to Nitrogen-Deficiency

“…3B). APX is mainly localized in chloroplasts (Gillham and Dodge, 1986). Hence, these results indicate that under the LN condition, despite no cultivar differences in electron fl ow to O 2 and subsequent disproportionation of O 2 -, there was a signifi cant difference in H 2 O 2 -scavenging capacity: Shirobeniya had a lower H 2 O 2 -scavenging capacity than Akenohoshi.…”

Effect of light irradiations on photosynthetic machinery and antioxidative enzymes duringex vitroacclimatization ofTylophora indicaplantlets

“…Increase in antioxidative enzyme activities other than the chloroplast region is indicative of the formation of ROS in mitochondria and peroxisome of different cellular components. The increase in APX activity of T. indica plantlets further suggests chloroplast-based detoxification of ROS via Mahler pathway, as 90% of total leaf APX is located in chloroplast (Gillham and Dodge 1986). GR is considered to be a key enzyme responsible for monitoring the reduced form of glutathione pool.…”

Photosynthesis and antioxidant activity in Jatropha curcas L. under salt stress

“…One, probably universal, response to changes in the external osmotic potential is the accumulation of metabolites that act as compatible (Gillham and Dodge, 1986). With accumulation that is proportional to the change in external osmolarity within species-specific limits, the protection of structures and osmotic balance supporting continued water influx (or reduced efflux) are well-known functions of osmolytes.…”