Changes in ribonucleic acid and polyribosomes as related to ribonuclease activities during development and germination of the castor bean seed

Abstract

Castor bean endosperms and embryos exhibit a decline in total RNA content (by up to 70%) during the latter stages of seed maturation. This loss also occurs when developing seeds are dried prematurely. A major decline in ribosomal RNA accounts for these observed changes, and is correlated with polyribosome degradation during development, and reformation during and following germination. There is an increase in ribonuclease (RNase) activity at the time of the decline in RNA, and enzyme activity gels reveal that a low M r fraction is present throughout the time when increased RNase activity is detectable. Upon imbibition of the mature dry or prematurely dried seeds, both tissues exhibit an increase in RNA.