A Plastid Mutation in Tobacco (Nicotiana tabacum L.) is Associated with Reduced Levels of Mitochondrial Cytochrome C Oxidase and Glycine Decarboxylase

Plant cells which have severely damaged chloroplasts do not produce specific nuclear-encoded proteins which function in other compartments. Many of these proteins are involved in the photorespiration pathway and are found in peroxisomes and mitochondria, while others are unrelated to photorespiration. We examined a chloroplast-inherited mutation (Vir-c) in tobacco (Nicotiana tabacum L.) in which chloroplast development proceeds much more slowly than in the wild type, spreading out the period when chloroplast-dependent events occur. We assayed for mitochondrial proteins known to be linked with chloroplast development or function, or assessed their amounts using western blots. We found that the appearance of the photorespiratory protein glycine decarboxylase (EC 2.1.2.10) closely followed the onset of greening in mutant seedlings. In contrast, the activity of cytochrome oxidase (EC 1.9.3.1), a non-photorespiratory enzyme, did not increase as chlorophyll accumulated and remained well below activity levels of wild-type seedlings. We discuss our findings and relate them to the appearance of chloroplast-dependent proteins which function in the peroxisome.