Development of Mitochondrial Activity in Pea Cotyledons Following Imbibition; Influence of the Embryonic Axis

Abstract

The development of mitochondria in cotyledons during the initial stages following imbibition and the subsequent degeneration were faster when the embryonic axis was attached. This was more clearly demonstrated when mitochondrial activity was determined using malate or ct-oxo glutarate as substrate rather than NADH or succinate. Cycloheximide did not inhibit the initial development of mitochondria in attached cotyledons, although it inhibited the incorporation of l4C-amino acid into protein. Abscisic acid inhibited almost completely the initial increase in mitochondrial activities of attached cotyledons. The activities of several enzymes in mitochondrial fractions were almost the same in attached and detached cotyledons during 4 d after imbibition. The degeneration of mitochondria was not accompanied by the loss of enzymes. It was inferred that the initial development and the subsequent degeneration of mitochondria in cotyledons during 4 d after imbibition was brought about by the structural improvement and disorganiz ation of mitochondria, respectively. The initial differences in the development of mitochondrial activities between attached and detached cotyledons were suggested to be attributable to differences in the development of the activities of electron transfer pathway from endogenous NADH to ubiquinone.