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Free amino acids and amines in leaf explants of Nicotiana tabacum cultivated in vitro on media inducing rhizogenesis or caulogenesis. Foliar explants of Nicotiana tabacum cv. Xanthi n.c. were cultivated on three different media: (1) a basal medium without hormone, so that no differentiation occurred in the explants; (2) with auxin added; and (3) with auxin plus cytokinin added, where the additions (2) and (3) promote rhizogenesis and caulogenesis, respectively. The content of free amino acids and amines of the three kinds of explants were investigated. In the two media lacking cytokinin, the explants contained great amounts of five amino acids (asparagine, glutamine, proline, glutamic acid and histidine) and of one aromatic amine, tyramine. In the cytokinin containing medium, only two amines accumulated in the explants: one aliphatic polyamine (putrescine) and one aromatic amine (phenethylamine). The increase in amino acids began immediately on the first days of culture. It was related neither to a more active proteolysis nor to the breaking of the correlations from the mother plant. It was induced by the addition of nutritional elements into the medium. On the other hand, the accumulation of aromatic amines occurred after a few days of culture and was transitory. A decrease was observed after the first emergence of new organs. The relation between the accumulations of these aromatic compounds and formation of roots or shoots is discussed.

Demonstration of amines connected with cellular structures in Nicotiana tabacum and Lycopersicum esculentum. The level of free and bound amines in various tissues of Nicotiana tabacum cv. Xanthi was investigated. After acid hydrolysis of different pellets from ethanol or buffer extractions, three aliphatic polyamines (putrescine, spermidine, spermine) and one aromatic monoamine (tyramine) were found in different proportions according to the nature of the tissue. Roots contain high quantities of insoluble tyramine bound very strongly to cellular structures. On the contrary, there were only traces of bound tyramine in leaves and stem. After extraction and purification of cell structures, tyramine was shown to be bound to one component of the cell wall. Addition of pronase or cellulase to the extract did not break the tyramine complex. In tobacco roots, insoluble tyramine concentration increased with plant development. High content of bound tyramine was also found in Lycopersicum esculentum roots. The possibility that tyramine binds with lignin is discussed.

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Demonstration of a regulatory effect of exogenous proline on the glycolate cycle in Nicotiana tabacum cv. Xanthi n.c. An exogenous proline supply in the light provokes an increase in free glycine concentration in apical tissues or leaf disks of vegetative Nicotiana tabacum cv. Xanthi n.c. The same phenomenon does not occur in the equivalent tissues of tobacco plants after floral induction, these being naturally rich in proline. Under different environmental conditions (light, dark, varying concentrations of CO2 and O2), the exogenous proline appears to modify one or more reactions of the glycolate pathway.