Effect of sucrose on growth and galanthamine production in shoot-clump cultures of Narcissus confusus in liquid-shake medium

In order to produce galanthamine, an alkaloid currently being tested in Alzheimer's disease therapy, we have used in vitro organ cultures of Narcissus confusus (Amaryllidaceae) plants starting from two different explants: double scale segments with basal plate from bulbs (organogenic cultures), and mature seeds (callogenic-organogenic cultures). Shoot-clumps were induced from buds obtained from twin-scales and from organogenic calluses on a MS medium supplemented with 1 mg l−1 2,4-D and 5 mg l−1 BA. Shoot-clumps were then developed partially submerged in a liquid medium. After one month of precondition, the shoot-clumps were cultured in liquid media with different concentrations of sucrose, from 3% to 18% (w/v) for 14 days. The growth of the regenerated plants treated with 9% sucrose was significantly greater. Under a photoperiod 16 h light/8 h dark, the shoot-clump cultures subjected to the two highest sucrose concentrations gave rise to higher dry weight/fresh weight ratios. Different doses of sucrose affected not only the alkaloid profile in the shoot-clump tissues but also that excreted to the medium. In all cases, shoot cultures of N. confusus were capable of galanthamine biosynthesis, with the best results at 9% sucrose concentration.