CHANGES IN THE FREE NUCLEOTIDE PATTERN OF PEA SEEDS IN RELATION TO GERMINATION.

1. Major changes in the free nucleotide and nucleoside pattern of germinating pea seeds are described. 2. During the imbibition phase of germination (0-16hr.) there was a 250% increase in ATP content and a parallel fall in AMP content without detectable change in ADP content. Metabolic implications are discussed. 3. The main nucleoside changes during imbibition were a 93% increase in xanthosine content and a 39% fall in adenosine content. 4. During the last phase of germination, leading to the emergence of the radicle, there is a general fall in free nucleotide content. AMP, ADP and ATP contents decreased 73, 48 and 52% respectively. Acetyl-3'-dephosphocoenzyme A concentration fell by 53%. However, the (NADP(+)+NADPH)/(NAD(+)+NADH) ratio increased, and except for uridine content (52% decrease) the nucleoside pattern changed little. 5. A sixfold increase in the concentration of an unidentified UDP-glycosyl compound occurs at this stage, although the content of UDP-glucose and UDP-galactose remained unchanged. 6. No free purine or pyrimidine bases could be detected at any stage of germination.