Manipulation of the morphogenetic pathways of Lilium longiflorum transverse thin cell layer explants by auxin and cytokinin

Excised tissues from transverse young stem sections of Lilium longiflorum w ere cultured on Murashige and Skoog medium supplemented with growth regulat ors at various concentrations. After 45 d in culture, the presence of alpha -naphthaleneacetic acid (NAA) in the culture medium at 5.4 muM resulted in bulblet formation while 2,4-dichlorophenoxyacetic acid (2,4-D) at 2.2 muM resulted in root formation. The presence of IBA (indole-3-butyric acid) in the culture medium at 1.0 muM resulted in shoot formation while plantlet fo rmation occurred when IBA was added at a concentration of 2.0 muM. When 1-p henyl-3-(1,2,3-thiadiazol-5-yl)-urea (TDZ) was added to the culture medium at 1.1 muM, protocorm-like bodies (PLBs) formed, while 2.2 LM resulted in s hoot formation (on abaxial and adaxial surfaces). The presence of NAA and T DZ in the culture medium at 5.4 muM and 0.4, 1.1 or 2.2 muM, respectively, resulted in somatic embryo formation while, NAA- and 6-benzylaminopurine- ( BA) containing culture medium formed callus or bulblets. The establishment of different regeneration systems when explants are exposed to various grow th regulators demonstrates that the choice of growth regulator combinations and concentrations are of significance in determining the morphogenetic re sponse and plant regeneration capacity.