Changes in Mitochondrial Properties Associated with Chloroplast Development in Jack Bean (Canavalia ensiformis [L.] DC.)

Procedures were developed to isolate actively respiring mitochondria from jack bean (Canavalia ensiformis [L.] DC.) leaves and cotyledons. Consistent respiratory control values of about 2 for succinate oxidation were obtained in preparations from etiolated cotyledons. Jack bean mitochondria oxidized malate with high respiratory control (2 to 5) and ADP/O (up to 2.8). Mitochondria purified from greening leaves and cotyledons exhibited rapid increases in respiratory control for up to 4 hours of light exposure followed by a decrease in activity. ADP/O values remained constant at about 1.2 while oxygen consumption per unit mitochondrial protein increased constantly during the first 14 hours of greening in preparations from cotyledons. The changes in mitochondrial respiratory activity during greening were correlated with the reversible appearance of mitochondria in the condensed conformation observed by electron microscopy. Both isolated mitochondrial pellets and cotyledon mitochondria in situ were shown to exhibit these changes in conformation during greening.