The incorporation of bacterial genes into the potato genome induces the formation of phenotypically different transformants that show expressive growth and metabolic changes. The transformants cv. Zvikov 1361 are noted for their excessive root formation which is stimuled by the presence of the plasmid Ri. It is necessary to limit the rhizogenesis in order to induce transformant tuberization. 2,3,5-triiodobenzoic acid and cumarin in the concentration 2 and 4 mg.1-1 TIBA or 25 and 50 mg.1-1 cumarin limit the root growth and induce axillary microtubers.
Another type has been derived by the transformation of the cv. Oreb with plasmid LDA 1334. This type also brings gene 4 into potatoes and induces higher synthesis of cytokinins. The transformants were noted for the formation of multiple shoots which were not able to produce roots and tubers on media modified by auxin substances. Only transformant grafting on a tomato has caused elongation and stem rooting in the soil and also the formation of tubers in flower-pots. The tubers were smaller and had a prolonged shape and contained few starch grains. During the analysis of amino acids it was remarkable to observe two to three times lower proline content. The shortage of proline in transformants could result in the lower resistance of transformants under less positive conditions.
In the next vegetation period we verified the influence of exogenously applied proline on transgenic cv. Oreb in leaves that were growing in an experimental field and in a hotbed. As a result of the bioassays on coleoptile oat segments, it is evident that proline in leaves lowers the content of auxin substances in most cases and evokes inhibitions. The changes suggest the possible presence of abscisic acid which could contribute to the regulation of leaf stomata.