Adventitious shoot organogenesis and plant regeneration from cotyledons of Dalbergia sissoo Roxb., a timber yielding tree legume

A procedure is outlined to induce adventitious shoot organogenesis from semi-mature as well as mature cotyledons lacking the embryonic axis of Dalbergia sissoo Roxb., an economically important leguminous tree. Shoot buds were induced in the proximal region of the semi-mature cotyledons on Murashige and Skoog's (MS) medium supplemented with 4.44 muM 6-benzyladenine (BA) and 0.26 muM proportional to-naphthaleneacetic acid (NAA). These buds elongated into shoots following transfer to a similar medium containing half-strength macro-nutrients. Adventitious shoot bud formation was also induced in the mature cotyledons. However, unlike the semi-mature explants, the mature cotyledons exhibited shoot bud differentiation on MS medium containing 22.20 muM BA without NAA. Pre-culture of mature cotyledons in liquid MS medium containing 8.88 muM BA for a duration of 48 h improved shoot bud regeneration up to six-fold. Regenerated shoots, derived from semi-mature and mature cotyledons, rooted on half-strength MS medium containing 1.23 muM and 4.92 muM indole-3-butyric acid (IBA), respectively. Plantlets were acclimatized and established in soil.