High Frequency Bulblet Formation in Scale and Stem Thin Cell Layer Explant Cultures of Lilium Oriental Hybrids

An efficient system for in vitro bulblet formation of Lilium oriental hybrids(cvs). Casa Blanca and Siberia is described. Transverse thin cell layer(tTCL)(1mm thick) explants of 'Casa Blanca' formed bulblets at a frequency of 97.7％ when cultured on Murashige and Skoog (MS) medium supplemented with 1mg/L 2,4 dichlorophenoxyacetic acid(2,4-D) (On average 15.6 bulblets were formed per explant). The frequency of bulblet formation was drastically reduced when the explant ghickness was thinner than 1 mm. Explants from the outermost layer of bulb scale produced greater frequency of bulblet formation than middle or innermost layer. Among auxins supplemented to culture medium at 1 mg/L, 2,4-D led to greater frequency of bulblet formation on explants than dicamba, picamba, or phenylacetic acid(PAA). tTCL explants from the middle region of the outermost layer bulb scale yielded greater frequency of bulblet formation than the upper or lower region. tTCL stem explants of 'Siberia' formed bulblets at a frequency of 95.3% when cultured on MS medium with 1 mg/L 2,4-D(On average 9.1 bulblets were formed per explant). The system estabilished in this study will be useful for in vitro rapid propagation and genetic transformation of Lilium Oriental hybrids.