Nutrient encapsulation of nodal segments of an endangered white cedar for studies of regrowth, short term conservation and ethylene inhibitors influenced ex vitro rooting

• Tecomella undulata: T. undulata an endangered timber yielding tree species, also plays a part in environmental conservation; possess anti-HIV, antioxidants, hepatoprotective and several other activities.
• Nutrient encapsulation: Due to the recent advances in encapsulation technology synthetic seeds of T. undualta could therefore be used for propagation as well as ex situ conservation.
• Shoot regrowth: In the present study encapsulation of nodal explants where gelling matrix was composed of sodium alginate, MS basal medium and PGRs proved efficient in terms of shoot regrowth and overall development.
• Ethylene inhibitors: Of all the rooting formulations tested 1.0 mM salicylic acid and 1.0 mM silver nitrate after an exposure of 15 min proved beneficial for root induction.
• Ex vitro rooting and potting substrates: Out of different potting substrates soilrite™ proved efficient in the production of more number of roots than vermi-compost and garden soil. Direct transfer of plantlets to greenhouse conditions after rooting exposure reduced the hardening phase.
• Germplasm conservation: Ex vitro conversion of shoots into plantlets in extremely simplified media such as soilrite™ and vermi-compost indicates that this method could be useful in developing a cost effective propagation protocol for such a germplasm in comparison to cryopreservation.

Studies on the conservation of white cedar (Tecomella undulata) are of worthwhile because of its potential advantages of various secondary metabolites, therapeutic usages combined with its endangered status. The present study was undertaken to investigate high efficiency regeneration system through encapsulated nodal segments of T. undulata excised from mature tissues. Highest regrowth and regeneration efficiency was achieved when the gelling matrix (3% sodium alginate in Murashige and Skoog’s (MS) basal medium) was supplied with 2.5 μM BA (6-benzyladenine) + 0.5 μM IAA (indole-3-acetic acid) followed by their plantation on to the nutrient medium composed of MS + 10.0 μM BA with the production of 6.50 ± 0.28 shoots/encapsulated nodal segment. The excised shoots were subjected to ex vitro rooting by exposing their cut ends to two different ethylene inhibitors [salicylic acid (2-hydroxybenzoic acid) and silver nitrate (AgNO3)] for 15 min followed by their transfer to different potting substrates. Soilrite™ and vermi-compost potting substrates proved equally better for healthy root formation directly, under greenhouse conditions. Multiple shoot formation from a single encapsulated bead along with ex vitro rooting and direct acclimatization under greenhouse conditions supports this protocol to be more efficient, cost effective and less time consuming coupled with clonal propagation.