Formation of vascular bundles in bulblets regenerated from scale of Lilium japonicum Thunb. in vitro

In vitro experiments were conducted to clarify the process of forming the vascular bundle system in regenerated bulblets from the mother scale of Lilium japonicum Thunb. cultured on MS medium. The medium contained 0.2mg.liter(-1) alpha-naphthaleneacetic acid (NAA) and 0.01mg.liter(-1) benzyladenine (BA) or 0.01mg.liter(-1) NAA and 2.0mg.liter(-1) BA or no plant growth regulators. There were one major and two minor vascular bundles in the scale of the bulblets cultured for 8 weeks in vitro. A collateral vascular bundle (CVB) exists in the scale and in the basal plate of the bulblets; a radial vascular bundle (RVB) differentiated in the roots developing from the basal plate of the bulblets. Major vascular bundles of the bulblet scale were connected to those of the scale two nodes below; minor ones were connected to the vascular bundle of the scale one node below. Root primodia were formed from the ring tissue at the basal plate of the bulblet. The regular system of vascular bundle was established in the regenerated bulblets cultured for 4 weeks on the medium without plant growth regulators, but it did not form on the medium containing 0.01mg.liter(-1) NAA and 2.0mg.liter(-1) BA. Many vascular bundle interlinkages are present in the central parr of the bulblets grown on the medium with 0.01mg.liter(-1) NAA and 2.0mg.liter(-1) BA. Thus, a high concentration of benzyladenine (BA) results in irregular Vascular bundle system in regenerated bulblets.