Authors: E Hammes A Hoffmann C Plieth UP Hansen
Publish Date: 2005/12/30
Volume: 227, Issue: 1, Pages: 11-15
Abstract
5and6Carboxy2′7′dichlorodihydrofluorescein diacetate DCFDA a permeative indicator of oxidative stress was loaded into dissected leaves of wheat in order to monitor the temporal development of reactive oxygen species DCF fluorescence was found to be constant under dark conditions Upon loading the leaves with salicyl hydroxamate a blocker of the alternative oxidase DCF fluorescence linearly increased in the dark This indicates a function of alternative oxidase in preventing reactive oxygen radicals in the mitochondria Upon illumination the DCF signal decreased within 5 min As illuminated chloroplasts would increase the load of reactive oxygen species the observed decrease cannot be assigned to the production of reactive oxygen species in the chloroplasts Three different putative mechanisms are considered which all assign an important role to lightinduced delivery of NADPH 1 direct quenching of DCF fluorescence by lightgenerated NADPH 2 lightstimulated activation of scavenging enzymes or 3 redirection of mitochondrial electron fluxes as caused by the delivery of excess redox equivalents NADH from the chloroplasts
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