EFFECTS OF GIBBERELLIN GA(7) ON KINETICS OF GROWTH AND TROPANE ALKALOID ACCUMULATION IN HAIRY ROOTS OF BRUGMANSIA-CANDIDA

Brugmansia candida, an indigenous South American plant, produces the t ropane alkaloids scopolamine and hyoscyamine, which are widely employe d in medicine as anticholinergic agents. In this research; hairy roots of Brugmansia candida, obtained through infection with Agrobacterium rhizogenes LBA 9402, were employed to produce these tropane alkaloids in vitro. The effects of different concentrations of GA(7) on kinetics of growth and alkaloid accumulation on two different hairy root clone s of B. candida were analyzed, and the influence of GA(7) on the numbe r of new branches and rates of elongation was also studied. On clone 7 A, GA(7) at concentrations of 10(-4), 10(-1), and 1 mg/l increased the exponential growth rate. Levels of 10(-1) and 10(-4) mg/l GA(7) eleva ted the scopolamine/hyoscyamine (S/H) ratios in the early phases of gr owth, but the sum of scopolamine plus hyoscyamine per flask (S + H) de creased during that period. When 1 mg/l GA(7) was used, the highest S/ H ratios were observed in late exponential/early stationary phases, bu t the highest S + H totals were obtained in mid-exponential phase. GA( 7) at levels of 10(-1) and, especially, 1 mg/l exerted a positive effe ct on formation, emergence, and rate of elongation of lateral roots (c lone 7A). On clone 7B, levels of 10(-1) and 1 mg/l GA(7) did not alter significantly the exponential growth rate. GA(7) in concentrations of 10(-1) mg/l induced increases in both S/H ratio and S+H totals in lat e phases of growth.