Developmental changes in the activity of messenger RNA isolated from germinating castor bean endosperm.

The capacity of polyadenylated RNA from developing castor bean endosperm to program protein synthesis in a wheat germ cell-free translational system has been examined. Although the use of micrococcal nuclease-treated wheat germ extracts demonstrated a low but significant content of translatable mRNA in dry seeds, a large scale increase in total translational capacity was observed during germination. The cellular content of translatable mRNA peaked on the 4th day of germination and subsequently declined. It is concluded that protein synthesis in castor bean endosperm cells during germination is directed by newly transcribed mRNA.