The control of chloroplast division in <italic>Funaria hygrometrica</italic> I. Patterns of nucleic acid, protein and lipid synthesis

Abstract

In the cycle of chloroplast and cell division initiated by removal of the leaves of Funana hygrometrica from the stem, replication of nuclear DNA is followed by chloroplast DNA replication and the formation of dumb-bell-shaped chloroplasts. The initial stages of dedifferentiation occurring prior to regeneration have been followed using 14CO2, radioactive-precursors of nucleic acid synthesis and various antibiotics, in an attempt to clarify the roles of nuclear and chloroplast DNA during chloroplast division. Results indicate that the synthesis of chloroplast lipids is dependent on the transcription of chloroplast DNA and on protein synthesis on chloroplast ribosomes. The nucleus transcribes messenger RNA for the formation of DNA-polymerase, the mRNA is translated on cytoplasmic ribosomes. This suggests that thechloroplast is a semi-autonomous organelle, dependent for its division upon the nucleus only for DNA-polymerase