Effects of Agrobacterium rhizogenes strains and other parameters on production of isoflavonoids in hairy roots of Pueraria candollei Grah. ex Benth. var. candollei

Using several explants of Pueraria candollei Grah. ex Benth. var. candollei and two strains of Agrobacterium rhizogenes (ATCC 15834 and 43057), hairy root cultures were established. Including 100 μM acetosyringone in the culture medium enhanced frequency of hairy root induction by up to 58 %. Subsequently, effects of inoculum size (IS) and temperature on growth and production of isoflavonoids in hairy roots were determined. Conditions of 1 % IS and 32 °C promoted the highest accumulation of total isoflavonoid content, up to 31.0 ± 22.6 mg/g dry weight (DW), in hairy roots. Moreover, culture of hairy roots at 32 °C decreased browning of hairy roots. Furthermore, this temperature promoted accumulation of the secondary metabolite daidzein; whereas, hairy root cultures at the stationary phase accumulated higher amounts of the isoflavonoid puerarin rather than daidzein.