Morphometric Analysis of the Growth of P<i>hsp70-ipt</i>Transgenic Tobacco Plants

Abstract

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