Studies on the free nucleotide pool and RNA components of detached leaves of Phaseolus vulgaris during root development

Abstract

Significant changes occur in the free nucleotide pool and RNA complement of bean petioles during the formation of roots by detached leaves. Initially, a general increase occurs in free nucleotide content with specific increases in the nucleoside 5′-triphosphates and UDP-glucose but by the time of root emergence the concentrations of ATP, CTP and GTP have decreased again and UDP-glucose has replaced ATP as the pre-dominant petiolar nucleotide. Increases in the petiolar free-nucleotide pool could not be accounted for by corresponding losses from the leaf laminae. Associated changes occurred in the RNA complement of rooting petioles, the most important of which, quantitively, was a 350% increase in the heavy ribosomal fraction. No changes could be detected in the nucleic acid fractions of the laminae. During the first 24 hr after excision, a large increase occurred in petiolar phosphodiesterase activity against RNA but base analysis of the various RNA fractions gave no evidence for a direct link between depolymerization of RNA and specific changes in the petiolar nucleotide pool.