Protein synthesis patterns : relevance of old and new messenger RNA in germinating maize embryos

The proteins synthesized during the first hours of seed imbibition were studied in axes and scutellum of maize embryos separately. Increase in fresh weight was followed in the embryonic axes through the germination period. Pulse labeling experiments with ¹⁴C-amino acids were carried out at two stages of development: 0 to 6 and 18 to 24 hours in the presence and absence of α-amanitin. The proteins were analyzed by two-dimensional gel electrophoresis and fluorography. Results showed a major pattern of proteins common to both tissues, axes and scutellum (`house keeping' proteins), besides the specific proteins synthesized by each tissue. In the axes, the changes in proteins observed between the periods of 0 to 6 and 18 to 24 hours of development seem to be due both to newly synthesized mRNA as well as to delayed translation of stored mRNA species.