Multiple Shoot buds formation through in vitro pseudobulb culture of medicinal orchid Dendrobium transparens Wall ex Lindl
Tapash Kumar Bhowmik, Md Mahbubur Rahman
An efficient protocol for micropropagation of Dendrobium transparens Wall ex Lindl. using the axenic pseudobulb segments, derived from in vitro germinated seedlings, was developed. For multiple shoot induction, the axenic pseudobulb segments excised from 120d old seedlings were cultured on MS medium supplemented with auxins (IAA, IBA, NAA, Picloram) and cytokinins (BAP, Kinetin). In vitro grown pseudobulb segments both upper and lower part directly produced multiple shoot buds via organogenesis. Average highest number of MSBs (7.42 ± 0.36/segment in lower part; 5.56 ± 0.32/segment in upper part) produced on MS medium with 1.0 mg/l NAA + 2.0 mg/l BAP followed by (7.24 ± 0.41/segment in lower part; 5.96 ± 0.37/segment in upper part) MS medium supplemented with 1.0 mg/l NAA + 2.0 mg/l BAP. Highest individual shoot bud increased length was recorded on 1.0 mg/l IAA + 1.0 mg/l BAP supplemented in both liquid PM (3.27±0.14cm) and followed by agar solidified PM (3.15±0.10 cm) medium. Elongation of shoot bud was better in liquid media than agar solidified condition and PM was found better than MS. Shoot bud derived seedlings were best responses as increase in length as well as the number of roots developed on agar solidified full strength MS medium with 1.0 mg/l IAA (4.06 ± 0.22cm/shoot bud and 1.87 ± 0.14no/shoot bud) followed by half strength hormone free MS medium with 1.5% (w/v) sucrose (3.75 ± 0.23cm/shoot bud and 1.64 ± 0.10no/shoot bud). The plantlets were hardened off and were released to the shade house.