A method for extracting intact chloroplast and cytoplasmic ribosomal RNA from leaves

A method is described for extracting intact chloroplast and cytoplasmic ribosomal RNA from leaves of two higher plant species. Sodium dodecyl sulfate (1%) and 25 mM magnesium ions are required to inhibit ribonuclease action during RNA purification by phenol deproteinization. The ethanol-precipitated RNA product, including 23s chloroplast ribosomal RNA, is completely stable during electrophoresis in the absence of magnesium ions, even in the presence of EDTA. The $\text{in}$$\text{vivo}$ mole fraction of chloroplast ribosomes relative to cytoplasmic ribosomes is estimated. Bentonite is shown to cause preferential losses of chloroplast RNA during extraction.