Recovery of labeled ribonucleic acid following administration of labeled auxin to green pea stem sections.

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Abstract
C14 from carboxyl-labeled indole acetic acid (IAA) fed to excised, growing green pea stem sections was progressively incorporated into RNA extractable by phenol. The kinetics of incorporation resembled the kinetics of growth induction by IAA. C14 from methylene-labeled IAA and from carboxyl and methylene labeled 2,4-dichlorophenoxyacetic acid were also incorpora ted into RNA, but with lower efficiency than from carboxyl-labeled IAA. Both growth and C14 incorporation into RNA were inhibited by 10[mu]g/ml actinomycin D. The label was incorporated into a light (4S) RNA fraction as shown by sucrose density gradient centrifuga-tion, while tritiated uridine simultaneously applied was incorporated into ribosomal peaks as well. Alkaline hydrolysis, followed by separation of the nucleotides by paper electrophoresis and thin layer chromatography showed that the bulk of the C14 label was associated wiih the adenylate region. Some activity from fed labeled IAA could also be detected in the form of unchanged IAA recovered from the alkaline hydrolyzate. It is concluded that some IAA couples per se with soluble RNA, while some of it is degraded, and the split products, including CO2, are used in resynthesis of RNA components.