Nucleic Acid, Mitochondria, & Enzyme Changes in Cotyledons of Peanut Seeds during Germination

Abstract

Studies on the changes in nucleic acids, protein, mitochondria, and enzymes in the storage parenchyma cells of the peanut (Arachis hypogaea) cotyledon show a rapid synthesis of nucleic acid, especially of RNA, and an increase in enzyme and mitochondrial respiratory activities while there is a 60% loss in dry weight and a depletion of 70% of the storage protein. During the 1st 8 days of germination the RNA content tripled and the pattern of change was very similar to the increase in activities of DPNH cytochrome c reductase, succinic cytochrome c reductase, glucose-6-P dehydrogenase and isocitrase as well as the respiratory activity of isolated mitochondria. After 8 days of germination the nucleic acids and the above-mentioned enzyme activities rapidly decreased with age. Concomitant with the in vivo degradation of RNA the RNAse activity increased several-fold. Electron micrographs showed that the cotyledon of resting seed contain few typical mitochondria, but many vesicular membranes. During the 1st 8 days of germination the mitochondria appear to increase in structure and internal organization. After 8 days the mitochondria swell and there is a large degree of disintegration.