SENESCENCE: HORMONAL CONTROL OF RNA AND PROTEIN SYNTHESIS IN EXCISED BEAN POD TISSUE

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Abstract
The kinetics of degradation of RNA, total protein, ribosomal and soluble (R‐S) protein and DNA were followed over 24 hours in excised segments of Kentucky Wonder pole beans (Phaseolus vulgaris). In absence of exogenous auxin, RNA degradation proceeded from about zero time. By 15 hours, after about 20% of the RNA had degraded, the degradation of DNA, total protein and R‐S protein was initiated. Exogenous auxin (25 ppm α‐napthaleneacetic acid) prevented these degradations. The addition of kinetin had little or no effect. Auxin enhanced incorporation of orotic acid into RNA two to several times more than it did amino acids into protein. Actinomycin D repressed RNA synthesis about 75% including a repression of auxin‐induced synthesis. It had no effect on the basal level of protein synthesis but did repress auxin‐induced synthesis. The results indicate that the primary action of auxin in preventing senescence of bean endocarp tissue is at the site of RNA synthesis, and the effect of auxin on DNA and protein is a consequence of the effect of auxin on RNA metabolism.
Funding Information
  • National Science Foundation (GB‐287)