Description:
<jats:title>Summary</jats:title><jats:p>Growth retardation is an important breeding aim and an essential part of horticultural plant production. Here, the potential of transferring the <jats:italic>Arabidopsis</jats:italic> short internode (<jats:italic>shi</jats:italic>) mutant phenotype was explored by expressing the <jats:italic>AtSHI</jats:italic> gene in the popular ornamental plant <jats:italic>Kalanchoë</jats:italic>. A 35S‐<jats:italic>AtSHI</jats:italic> construct was produced and transferred into eight genetically different cultivars of <jats:italic>Kalanchoë</jats:italic> by <jats:italic>Agrobacterium tumefaciens</jats:italic>. The resulting transgenic plants showed dwarfing phenotypes like reduced plant height and diameter, and also more compact inflorescences, as a result of increased vegetative height. The <jats:italic>shi</jats:italic> phenotype was stable over more than five vegetative subcultivations. Compared with <jats:italic>Arabidopsis</jats:italic>, the ectopic expression of <jats:italic>AtSHI</jats:italic> in <jats:italic>Kalanchoë</jats:italic> showed several differences. None of the <jats:italic>Kalanchoë</jats:italic> SHI‐lines exhibited alterations in leaf colour or morphology, and most lines were not delayed in flowering. Moreover, continuous treatment of lines delayed in flowering with low concentrations of gibberellins completely restored the time of flowering. These features are very important as a delay in flowering would increase plant production costs significantly. The effect of expression controlled by the native <jats:italic>Arabidopsis SHI</jats:italic> promoter was also investigated in transgenic <jats:italic>Kalanchoë</jats:italic> and resulted in plants with a longer flowering period. Two <jats:italic>AtSHI</jats:italic> like genes were identified in <jats:italic>Kalanchoë</jats:italic> indicating a widespread presence of this transcription factor. These findings are important because they suggest that transformation with the <jats:italic>AtSHI</jats:italic> gene could be applied to several species as a tool for growth retardation, and that this approach could substitute the use of conventional chemical growth regulation in plant production.</jats:p>