INDUCTION OF CROWN GALLS BY AGROBACTERIUM-TUMEFACIENS (STRAIN C58) REVERSES ASSIMILATE TRANSLOCATION AND ACCUMULATION IN KALANCHOE-DAIGREMONTIANA

The mechanism of hormone-enhanced solute accumulation was investigated in crown galls of Kalanchoe diagremontiana, induced by Agrobacterium tumefaciens (C58). Electrophysiological, cytological staining, and (CO2)-C-14-tracer techniques were used. Intracellular auxin and zeatinriboside concentration increased in tumours by three and five times, respectively, compared with the mesophyll. In contrast, the electrical membrane potential difference, in particular the energy-dependent component across the plasma membrane of tumours was at least 60mV smaller than that of mesophyll cells. The detection of functional sieve tubes, metabolically active companion cells and also developed xylem vessels correlated well with evidence for reversed, long-distance, C-14-labelled assimilate flow from CAM-performing mesophyll to sugar and potassium-accumulating tumours. The change in hormone production, encoded by the iaaM, iaaH and ipt T-DNA genes, apparently induced functioning vascular bundles and established a strong sink. From a comparison with tobacco suspension cells (SR1 and SR1-C58), the changes in the amino acid pattern in the mesophyll/tumour complex can be attributed to the enzymatic activities incited by the nos encoding gene. Differences in sugar and inorganic ion content were not apparent in the transformed suspension cells, indicating that the increase in extracellular concentration by enhanced Phloem unloading may be the crucial factor for the pathological solute accumulation in the tumours.