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On the Cover: Following periods of high irradiance, sunflower leaves are capable of nonphotosynthetic reduction of plastoquinone in the thylakoid membrane for sustained periods in the dark. In Feild et al. (pp. 1209-1218), the net dark plastoquinone reduction is shown to be sensitive to the mitochondrial NADH dehydrogenase inhibitor rotenone, stimulated by the hemoprotein oxidase inhibitor CO, and reversed by PSI activity driven by far-red illumination. The data are evidence of a chlororespiratory electron transport pathway in higher plant chloroplasts. Although the rate of electron flux is low, about 3% of the maximum rate of photosynthetic electron flux, chlororespiration may play a central role in recycling pyridine nucleotides required for dark chloroplast processes such as starch mobilization.