Expression of bacterial isochorismate synthase (EC 5.4.99.6) in transgenic root cultures ofRubia peregrina.

The gene coding for isochorismate synthase (EC 5.4.99.6) was amplified by the polymerase chain reaction fromEscherichia coli, cloned into a binary vector. and mobilised intoAgrobacterium rhizogenes LBA9402 which was used to transformRubia peregrina. Transgenic roots containing bacterial isochorismate synthase cDNA expressed twice as much isochorismate synthase activity (4.88 pkat/mg protein) as the control roots (2.45 pkat/mg protein) after 10 days in culture, and accumulatedca. 20% higher levels of total anthraquinones after 30 days in culture. Whilst the amount of total alizarin (free and bound) in the transgenic roots was 30% higher than in control roots, the level of free alizarin wasca. 85% higher.