In vitro propagation of miyamasukashi-yuri (lilium maculatum thunb. var. bukosanense), an endangered plant species

Lilium maculatum var. bukosanense (Honda) Hara, called Miyamasukashi- yuri in Japanese, is a wild lily, considered as critically endangered in Japan. Before L. maculatum var. bukosanense is lost, attempts for in vitro propagation can be performed to provide information for its rescue, efficient ex situ conservation as well as for possible use in breeding programs to be used as ornamental plant. For bulblet induction, five scales from aseptic bulbs were used for each treatment and placed in the MS (half-strength) medium, supplemented with sucrose 3 %, agar 0.8 %, at pH 5.8, and the effect of two plant growth regulators (PGR): #945;-naphthaleneacetic acid (NAA) at 0.0, 1.0, and 2.0 mg L-1, in combination with thidiazuron (TDZ) at 0.0 and 0.5 mg L-1, were studied. Two illuminating conditions (light or darkness), and the presence or absence of activated charcoal (AC) in the medium were also tested. A total of 16 treatments were tested. Explants cultured under light and AC did have a favorable effect on bulblet induction. The average number of induced bulblets under light condition was the double (4 per explant) than those induced under darkness, both in presence of AC, irrespective of PGR level. The best treatments were those with NAA 2 mg L-1 + TDZ 0.5 mg L-1, and without PGR, all of them with AC and under light. After 12 weeks of culture, an average of 2.4 well-formed bulblets was obtained per responsive explant...