Morphometric Analysis of the Growth of Phsp70-ipt Transgenic Tobacco Plants

The effect of introducing a supplementary ipt</it>-gene into the genome of Nicotiona tabacum</it> L. cv. Petit Havana SR 1 is studied on the morphological plant development. The ipt</it>-gene, accounting for the biosynthesis of cytokinins, was coupled to the heat-inducible hsp70</it>- promoter from Drosophila melanogaster</it>. Besides the influence of the hormonal changes involved, the effects of the experimental conditions are examined, namely the in vitro</it> growth conditions for selecting transformed plants and the heat treatment to induce ipt</it>-gene expression. The phenotype of the plants is determined by the tissue sensitivity to three factors: (1) heat treatment reduces stem elongation and diameter growth; (2) in vitro</it> pre-cultivation also reduces stem elongation; and (3) expression of the ipt</it>-gene stimulates diameter growth, induces debudding of the axillary shoots and inhibits root development. In addition, axillary bud development indicates that in vitro</it> cultivation affects ipt</it>-gene expression.