Developmental regulation of respiratory activity and protein import in plant mitochondria

Abstract

In eukaryotic cells, the role of mitochondria is to generate both ATP (through the process of oxidative phosphorylation) and carbon skeletons (via the Krebs cycle) for biosynthetic purposes. In non-green plant tissue ATP demand is met entirely through the mitochondrial ATP synthase; however, in photosynthetic tissue the situation is more complex. ATP demands in photosynthetic tissues can be satisfied either through the mitochondrial ATP synthase or through the process of photophosphorylation which allows ATP generated in the chloroplast stroma to be indirectly transferred to the cytosol [1,2]. In addition, in any plant organ there exists not only a range of cell types but also a range of cell ages [l]. It has been shown that the function of both mitochondria and chloroplasts is developmentally regulated and that distinct biochemical and morphological changes can be observed as the plant tissue develops and becomes more photosynthetically active [3]. These changes appear to be dependent upon a number of factors that can include cell maturity, tissue location and the interaction of a number of organelles, chiefly Abbreviation used: mtHSP70, matrix-located 70 kDa heat-shock protein.