Appearance of poly(A)-rich RNA in germinating pea seeds.

1. The affinity chromatography on poly(U)-Sepharose 4B provided evidence for the absence of poly(A)-rich fragments in RNA from embryo axes of dry pea seeds, and for appearance of these fragments after 2 h of swelling. 2. The percentage of the poly(A)-rich RNA fraction remained unchanged in the initial phase of germination (up to 68 h). 3. The poly(A)-rich RNA fraction was found to promote protein synthesis in vitro more than did the poly(A)-poor fraction. 4. Ribonuclease A and T1-resistant fragments isolated from the poly(A)-rich RNA contain 70-80 nucleotides, 78% of which are adenine nucleotides. 5. It seems that polyadenylation of a part of mRNA preexisting in dry pea seeds precedes the initiation of protein biosynthesis.