EXPRESSION OF THE AGROBACTERIUM-RHIZOGENES ROLC GENE IN A DECIDUOUS FOREST TREE ALTERS GROWTH AND DEVELOPMENT AND LEADS TO STEM FASCIATION

We have altered the growth and development of a deciduous forest tree by transforming hybrid aspen (Populus tremula x Populus tremuloides) w ith the Agrobacterium rhizogenes rolC gene expressed under the strong cauliflower mosaic virus 35S promoter. We demonstrate that the genetic ally manipulated perennial plants, after a period of dormancy, maintai n the induced phenotypical changes during the second growing period. F urthermore, mass-spectrometrical quantifications of the free and conju gated forms of indole-3-acetic acid and cytokinins and several gibbere llins on one transgenic line correlate the induced developmental alter ations such as stem fasciation to changes in plant hormone metabolism. We also show that the presence of the RolC protein increases the leve ls of the free cytokinins, but not by a process involving hydrolysis o f the inactive cytokinin conjugates.