Somatic embryogenesis and plant regeneration from cotyledon explants of a timber-yielding leguminous tree,Dalbergia sissoo Roxb.

Efficient plant regeneration through somatic embryogenesis was achieved from callus cultures derived from semi-mature cotyledon explants of Dalbergia sissoo Roxb., a timber-yielding leguminous tree. Somatic embryos developed over the surface of embryogenic callus and occasionally, directly from cotyledon explants without intervening callus phase. Callus cultures were initiated from cotyledon pieces of D. sissoo on Murashige and Skoog (1962) medium supplemented with 4.52, 9.04, 13.57, and 18.09 μmol/L 2,4-dichlorophenoxyacetic acid and 0.46 μmol/L Kinetin. Maximum percentage response for callus formation was 89 percnt; on MS medium supplemented with 9.04 μmol/L 2,4-D and 0.46 μmol/L Kn. Somatic embryogenesis was achieved after transfer of embryogenic callus clumps to ½-MS medium without plant growth regulators (1/2-MS0). Average numbers of somatic embryos per callus clump was 26.5 on ½-MS0 medium after 15 weeks of culture. Addition of 0.68 mmol/L L-glutamine to ½-MS0 medium enhanced somatic embryogenesis frequency from 55 percnt; to 66 percnt; and the number of somatic embryos per callus clump from 26.5 to 31.1. Histological studies were carried out to observe various developmental stages of somatic embryos. About 50 percnt; of somatic embryos converted into plantlets on ½-MS0 medium containing 2 percnt; sucrose, after 20 days of culture. Transfer of somatic embryos to ½-MS0 medium containing 10 percnt; sucrose for 15 days prior to transfer on ½-MS medium with 2 percnt; sucrose enhanced the conversion of somatic embryos into plantlets from 50 to 75 percnt;. The plantlets with shoots and roots were transferred to ½ and ¼-liquid MS medium, each for 10 days, and then to plastic pots containing autoclaved peat moss and compost mixture (1 : 1). 70 percnt; of the plantlets survived after 10 weeks of transfer to pots. 120 regenerated plantlets out of 150 were successfully acclimatised. After successful acclimatisation, plants were transferred to earthen pots.