DNA and histone synthesis are uncoupled during germination of maize embryos

Abstract The rate of synthesis of DNA and histones was studied in germinating maize embryos as a function of the length of the germination period. To that end excised embryos from seeds germinated for different periods of time were pulse labelled either with [ 14 C]protein hydrolysate or with [ 3 H]TdR. Specific activities were determined for the total cellular proteins and the total histone fraction obtained by acid-extraction of the cellular homogenate and BioRex70 ion exchange chromatography. The results show that the early germination period is characterized by a lack of coupling between the histone synthesis and that of the nuclear DNA. The early histone synthesis peak might be necessitated by the reprogramming of the embryo genome that takes place during germination.