Vanilla planifolia is a tropical orchid mainly known for the aromatic flavor of its cured pods. Callus cultures were initiated from leaf and nodal explants of V. planifolia. Leaf explants showed better callus initiation than the nodal explants with callus biomass production maximal when cultured on Murashige and Skoog (MS) basal medium containing 4.52 mM 2,4-dichlorophenoxy acetic acid and 2.22 mM benzyladenine (BAP). Callus transferred to MS basal medium supplemented with 13.32 μM BAP, and 13.43 μM naphthaleneacetic acid (NAA) showed superior growth response and produced 14.0±1.0 shoots with an average length of 3.6 ± 0.1 cm after 40 d. Subsequent transfer of the proliferated shootlets to MS basal medium supplemented with 8.88 μM BAP and 8.08 μM NAA produced 12.3±0.14 plantlets with an average height of 3.6 cm±0.10 cm. All plantlets produced profuse rooting within 35-40 d after transfer to halfstrength MS basal medium supplemented with NAA in combination with indole-3-acetic acid. Rooted plantlets were transferred for hardening, with 80% of the plantlets becoming successfully established in the field. Potentially, more than 100,000 plantlets could be produced within eight subcultures from callus obtained from leaf explant through the methods described here.

Stevia rebaudiana is and an important non-caloric sweetening herb contains diterpene glycosides need to be explored for its commercialization. The evolving commercial importance of secondary metabolites in recent years has resulted in a great demand in the Pharma industry. Callus cultures were established from nodal and leaf explants. Leaf explants showed better callus initiation than nodal explants. Maximum callus biomass was observed in MS medium supplemented with 2, 4-D 1.0 mg/l. Further screening of callus culture was carried out on Murashige and Skoog (MS) medium with different concentration and combinations of 2, 4-D, NAA, IAA, IBA, BA and KN individually and in combinations. Remarkable callus biomass of 11.6 g/l dry weight (182.3 g/l fresh weight) was observed in MS media containing 0.5 mg/l 2, 4-D, 0.5 mg/l NAA and 1.0 mg/l KN. The harvested cell biomass was subjected to extraction of active principles. In this study, cell biomass extracts were compared with extracts from leaves of mother plants of Stevia rebaudiana. HPLC analysis of these extracts showed that the main components of the active principles namely Stevioside were present in sufficiently large amounts in the undifferentiated cultured cells. Keywords: In vitro culture; Biomass; Stevia rebaudiana; Stevioside DOI: 10.3329/bjsir.v45i3.6532Bangladesh J. Sci. Ind. Res. 45(3), 243-248, 2010

Juvenile leaf explants of Stevia rebaudiana Bertoni produced maximum callus than the nodal explants cultured on MS containing 11.31 µM 2, 4-D and 2.22 µM BAP. Callus transferred to MS supplemented with 4.44 µM BA and 1.34 µM NAA showed better growth response and produced 14.0 ± 1.0 shoots with an average length of 5.6 ± 0.1 cm after 28 days. All plantlets produced profuse rooting within 25 days after transfer to half strength of MS basal medium supplemented with 2.46 µM IBA. Rooted plantlets were transferred for hardening, with 90% of plantlets successfully established in the field.

Shoot tip explants of Exacum travancoricum, an endangered herb mainly known for ornamental purpose grown on MS with 4.44 μM BAP and 1.34 μM NAA showed better growth response and produced 29.3 ± 0.3 shoots per explant with an average length of 4.6 ± 0.1 cm after 35 days. Roots were induced after transfer to half strength of MS supplemented with 2.46 μM IBA produced 4.8 ± 0.62 roots with an average height of 3.6 ± 0.10 cm after 30 days. The rooted plantlets were transferred for hardening, 80 per cent of plantlets survived and resumed growth in the mixture of soil, vermiculite and farm yard manure (1 : 1 : 1).

An efficient plant regeneration protocol was developed for Justicia gendarussa Burm.f. (Acanthaceae), an important medicinal shrub. Nodal segments grown on Murashige and Skoog (MS) medium containing 1.0 mg/l Benzyl adenine (BAP) with 10 % coconut milk showed better growth response and produced 10.5 ± 0.6 shoots per explant with an average length of 4.4 ± 0.3 cm after 35 days. Rooting of shoots was achieved on growth regulator free half strength MS medium produced 5.3 ± 0.25 cm roots with an average height of 4.8 ± 0.2 cm after 30 days. The rooted plantlets were transferred for hardening, 80 % of plants were successfully established in the field. Key words: Justicia gendarussa; Nodal segments; Regeneration; Coconut milk. DOI: http://dx.doi.org/10.3329/bjsir.v46i2.4388 Bangladesh J. Sci. Ind. Res. 46(2), 201-204, 2011