In vitro micropropagation of Allium giganteum R., 1: Callus and shoot formation, and regeneration of plantlet through in vitro culture of emerged young leaves

For in vitro micropropagation, we investigated the effects of plant growth regulators, gelling agents sucrose concentrations and light condition on callus and shoot formation, and plantlet regeneration using explants from emerged young leaves of Allium giganteum. 1. Higher concentrations of 6-benzylaminopurine (BA) and alpha-naphthalene acetic acid (NAA) stimulated callus and shoot formation, and the maximum rates of them showed 100 and 27 %, respectively on the medium containing 1 mg/l of BA and 10 mg/l of NAA. There were little differences in callus and shoot formation between the 2 gelling agents; agar and gellum gum. 2. Abscisic acid (ABA) inhibited callus and shoot formation, in particular on the medium with 10 mg/l of ABA no callus and shoot formation was observed. Sucrose at 2 % enhanced callus and shoot formation more effectively. In addition, explants cultured under the dark condition (continuous dark) could get more vigorous calluses and shoots than those under the light condition (14 hr/photoperiod), under which callus growth and shoot formation tended to be inhibited. 3. Shoot formation from transplanted calluses was most enhanced at 8 % sucrose, and so did shoot number per callus. The consequent development of shoots which formed at 8 % sucrose, however, inhibited. 4. Plantlet regeneration and bulblet formation were observed when shoots were transplanted on the root-inducing medium supplemented with 0.1 mg/l of IBA