Growth in Vitro of Marigold and Tobacco Tissue with Nucleic Acids and Related Compounds

Abstract

Tobacco tissue of normal originTrom the hybrid Nicotiana glauca X N. langsdorffii originally isolated and supplied by Philip White, and marigold tissue of crown gall origin isolated in this laboratory, were grown in chemically defined culture media with addition of nucleic acids, their components or the antimetabolite thiouracil. Growth was strikingly stimulated by both filtered and autoclaved RNA at concentrations of 400 and 4000 mg per liter, while DNA had no effect at low concentrations and was strikingly inhibiting with 4000 mg per liter. RNA was furthermore an excellent source of nitrogen for the tobacco tissue but not for marigold tissue. DNA was not a good source of nitrogen for either tissue. Neither RNA nor DNA was a source of carbon for tobacco tissue. Tobacco tissue was inhibited by 400 mg per liter by adenine, cytosine, xanthine, thy mine, and uracil, while hypo-xanthine, guanine and ribose supported progressively more growth with increasing concentrations. Marigold cultures were inhibited by 400 mg/ liter of all the purines and pyrimidines. Adenine and guanine were the most inhibiting. Some stimulation occurred with low concentrations of cytosine, guanine, and uracil and with ribose. The antimetabolite thiouracil was strikingly inhibitory to tobacco cultures with concentrations of 10 or more mg per liter. Marigold cultures were inhibited by this compound only at 100 mg per liter. The amounts of RNA that inhibited or stimulated these cultures, respectively, appeared comparable to the amounts inside stimulated dark green or inhibited light green tobacco leaves infected with TMV, which might clarify the characteristic mosaic symptoms.