A Chromatographic-Spectrophotometric Method for Determining Nucleotide Composition of RNA in Plants

Studies on the ribonucleic Acid from wheat leaves and chloroplasts

The chloroplast, leaf ribosomal, and leaf total RNA from seedlings of 2 varieties of Triticum durum and 3 varieties of Triticum vulgare were compared. For a given RNA preparation the major nucleotide composition was the same for all varieties. Irrespective of the variety, the chloroplast total RNA had a higher cytidylic and a lower adenylic acid content than the leaf ribosomal RNA, whereas, the guanylic and uridylic acid content of all RNA preparations was essentially the same. Pseudouridylic acid was present in all RNA preparations and was consistently higher in the durum than the vulgare varieties for leaf ribosomal RNA and leaf total RNA. The leaf ribosomal RNA of all varieties had 2 sub-units with sedimentation coefficients of approximately 18 S and 25 S. The molecular weight of the faster sedimenting subunit was about 2 times that of the slower sedimenting subunit.

Extraction of nucleic acids from lyophilized plant material

Four methods for extracting nucleic acids from lyophilized cotton (Gossypium hirsutum L. cv. Stoneville 62) leaves and roots were compared. They were based on the use of: (I) HC10(4); (II) KOH; (III) a mixture of 90% phenol, Tris (hydroxymethyl) aminomethane buffer, and sodium lauryl sulfate; and (IV) NaCl. (I) extracted large amounts of RNA but little DNA and extracted much carbohydrate and protein contaminants. (II) gave a good yield of both RNA and DNA but extracted such large amounts of contaminating material that purification of RNA on an anion exchange column was necessary. (III) extracted only part of the RNA and practically no DNA, but extracted contaminating materials. (IV) resulted in high yields of both RNA and DNA when modified to omit preliminary acid extraction of impurities. The use of cold trichloroacetic acid instead of ethanol, to precipitate NaCl-extracted nucleic acids, separated the nucleic acids from most of the carbohydrate and acid-soluble phosphate contaminants and resulted in good agreement among results by ultraviolet absorbance, pentose tests, and phosphate analysis. This method also resulted in lower protein contents and better ultraviolet absorption spectra than the other methods tested. Nucleic acids were extracted from leaves of 14 other species of plants, in addition to cotton, by this modified NaCl procedure.