Effect of light on cell elongation, nucleic acid and protein synthesis in hypocotyls of Lupinus angustifolius.

The synthesis of DNA, RNA, protein and dry matter was followed in the elongating cells of hypocotyl of Lupinus (Lupinus angustifolius L.) germinating in total darkness or in continuous light. Light strongly inhibits the synthesis of DNA, RNA and protein. It was shown by histofluorometric DNA determinations that a reduced synthesis of DNA in continuous light is accompanied by a lower level of endomitosis in the cortex cells of the hypocotyl. In the dark cortex nuclei become 8 C while in the light they become only 4 C. The more pronounced differences between dark and light germinated hypocotyls of lupinus in comparison with pea epicotyls is explained to a great extent by mitotic growth.