Deoxyribonucleic Acid and Ribonucleic Acid Synthesis during the Cell Expansion Phase of Cotyledon Development in Vicia faba L.

In Vicia faba L., the tissue specific proteins, legumin and vicilin, are synthesized during the cell expansion phase of cotyledon development. During this growth period, RNA and nuclear DNA increase 8- to 10-fold. (3)H-Uridine and (3)H-adenosine are incorporated into ribosomal RNA, both 25S and 18S, and into transfer RNA. DNA isolated from cotyledons in the cell division phase of growth has been compared with DNA isolated from cotyledons undergoing expansion growth. Results indicate that the DNA increase involves replication of the whole genome (endoreduplication).