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

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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.