Shamsul H. Prodhan

An efficient callus initiation and direct regeneration of Stevia rebaudiana

The experiment was carried out to establish an efficient callus induction system of Stevia rebaudiana from a variety of explants as well as direct regeneration from nodes. Callus initiation was done to extract secondary metabolites. However direct regeneration is essential for rapid large-scale clonal propagation. Among leaf, node and inter-nodal explants, the best callus initiation performance was observed by nodes. MS medium fortified with α-naphthalene acetic acid (NAA) 2.0 mg/L + 6-benzyladenine (BA) 2.0 mg/L showed the highest (93.33 ± 6.67%) callus induction by nodal explants. Though inter-nodal explants showed a moderate response (73.33 ± 6.67%) for callus induction in MS medium complemented with NAA 3.0 mg/L + BA 1.0 mg/L, nodal explants showed higher response (86.67 ± 13.33%) than inter-nodal explants in that nutritional environment. Leaf explants always showed very poor callus. However, the best direct regenerating medium was MS medium + BA 1.0 mg/L for multiple shoot proliferation and then transferring those shoots to ½ MS medium + NAA 1.0 mg/L for root formation. Key words: In vitro , Stevia rebaudiana , 2,4-D, α-naphthalene acetic acid (NAA), 6-benzyladenine (BA), plant growth regulators.

Efficient Callus Initiation and Plantlet Regeneration of Citrus japonica Margarita

In vitro approaches has become necessary for overcoming the hurdles of cultivation of Citrus, a commercially important fruit. The present study deals with establishment of protocol for micro propagation of Citrus Japonica Margarita through callus induction and regeneration. Mature seeds of this variety of citrus are used as explant. The Explants were cultured on Murashige and Skoog medium (MS) containing 30 g/L sucrose and 7 g/L agar supplemented with different concentrations and combinations of different phyto-hormones; 6- benzylaminopurine (BA), naphthalene acetic acid (NAA), 2,4-dichloro phenoxy acetic acid (2,4 D). The maximum callus induction (88%) was observed from the mature seeds of Citrus japonica observed on MS medium supplemented with 2,4 D 16 μM. Maximum shoot regeneration response (70%) was observed on MS medium supplemented with BA 13.0 μM. Maximum root regeneration response (80%) was observed on MS medium supplemented with IBA 10 μM and when it is supplemented with NAA 5 μM it is 70%. The regenerated plantlets were successfully acclimatized in pots containing sterile soil mixture to study their response in in vivo conditions.