Enhancement of DNA polymerase activity in potato tuber slices

DNA polymerase was extracted from potato (Solanum tuberosumL.) tuber discs and the temporal correlation of its activitychange to DNA synthesis in vivo was examined during aging ofthe discs. Most of the DNA polymerase was recovered as a boundform in the 18,000?g precipitate. Reaction with the bound-formenzyme was dependent on the presence of four deoxynucleosidetriphosphates, Mg²⁺, and a template. "Activated" DNA and heat-denaturedDNA, but not native DNA, were utilized as templates. The polymeraseactivity was sensitive to SH reagents. Fresh discs, which donot synthesize DNA in vivo, contained a significant amount ofDNA polymerase and its activity increased linearly with timeuntil 48 hr after slicing and became four times that of freshdiscs after 72 hr, whereas the activity of DNA synthesis invivo increased with time and decreased after reaching a maximumat 30 hr. Cycloheximide inhibited the enhancement of polymeraseactivity. DNA polymerase from aged and fresh discs had identicalrequirements for deoxynucleotides and a template in their reactions,sensitivity to SH reagent, and affinity to thymidine triphosphate. (Received February 18, 1977; )