Effect of light on nucleic-acid synthesis and polyploidy level in elongating epicotyl cells of Pisum sativum.

The synthesis of DNA and RNA and the increase in dry matter were followed in the elongating cells of the epicotyl of peas (Pisum sativum L.) germinating in total darkness or in continuous light. The amounts of DNA and RNA per epicotyl were estimated by chemical methods, the amount of DNA per cell was measured by histophotometric techniques. The increase in DNA, RNA and dry matter in the epicotyl cells is much higher during germination in darkness than in light. During elongation in the dark most cortical epicotyl cells reach the 8C polyploidy level, in the light only the 4C polyploidy level is reached. A decrease in RNA synthesis is in agreement with a reduction in nuclear volume.