Changes in the ribonucleic acid of senescing radish leaves

Abstract

Senescing radish leaves, whether attached or detached, exhibited typical downward drifts in total nucleic acid, protein, and chlorophyll, which agreed well with those reported for other species. MAK column profiles of the ribonucleic acid (RNA) from senescing leaves revealed a third peak in the ribosomal region, in addition to the usual heavy and light ribosomal RNA. The new peak eluted before light ribosomal RNA and retained its prominence while the other two diminished in size, suggesting it was a degradation product. The peak was not apparent until the first decreases in total RNA of the leaves signaled the beginning of senescence. No marked changes were observed in the soluble RNA region of the MAK column profile, but an oligonucleotide portion of RNA not retained by the column was prominent in mature leaves. This rapidly diminished in quantity as senescence advanced.