Mitochondrial structure and function in plants

Aerobic respiration is a process common to almost all eukaryotic organisms and involves the controlled oxidation of reduced organic substrates, carbohydrates, lipids, amino acids and organic acids, to CO2 and H2O, in mitochondria. This releases a large amount of free energy which is conserved in the acid anhydride linkages of ATP molecules. In addition, the primary pathways of respiration provide metabolic intermediates that serve as substrates for the synthesis of nucleic acids, amino acids, fatty acids, and many secondary metabolites. While the general process of respiration in plants is the same as in other eukaryotes, a number of specific features are unique to plants. These modifications apparently evolved to cope with the unique environmental and metabolic circumstances commonly faced by plants. Plant mitochondria, especially those in leaves, also participate in several unique synthetic and oxidative pathways, including those involved in glycine metabolism, folic acid, lipoic acid, biotin and ascorbic acid synthesis (Ravanel et al., Chapter 12, this volume). This introductory chapter provides an overview of the basic structure and function of plant mitochondria and is intended to provide sufficient background to lead the reader into the more detailed subsequent chapters. For a more detailed overview of plant mitochondrial function, the reader is directed to Siedow and Day (2002).