Expression of the rolC gene and nicotine production in transgenic roots and their regenerated plants.

Transformation of Nicotiana tabacum cv. Xanthi leaf sections with the pPCV002-ABC (rol genes A, B and C together under the control of their own promoter) or pPCV002-CaMVC (rol gene C alone under the control of the CaMV 35S promoter) construction present in trans-acting Agrobacterium tumefaciens vectors yielded several transgenic root lines. The two types (rolABC and rolC) of transgenic root lines were examined for their nicotine productivity in relation to growth rate and the amount of rolC gene product measured with specific antibodies. In all cases, the changes in the amount of this polypeptide were positively correlated with the capacity of the transgenic roots to grow and produce nicotine. Both capacities were greatly increased when the rolA, rolB and rolC genes were present together, which demonstrates that the activity of the three rol-gene-encoded functions is synergistic. Consistent observations were also made in the corresponding regenerated plants.