Shoot regeneration from petiole explants ofSimmondsia chinensis(Link) Schneider

SummaryA method has been developed for in vitro shoot regeneration from in vivo and in vitro petiole explants of Simmondsia chinensis. Efficient shoot regeneration could be initiated on Murashige and Skoog (MS) medium supplemented with thidiazuron (TDZ). Shoot regeneration was influenced significantly by the size of the leaf attached to the petiole and the orientation of the in vivo explant (i.e., vertical or horizontal). Petioles obtained from pruned branches of plants responded better than those from normal plants (unpruned). Explants placed horizontally on MS medium supplemented with 2.76 µM TDZ resulted in 70.3% regeneration. When in vitro leaves were placed on MS medium containing filter-sterilised 0.46 µM TDZ, regeneration was 71%.The efficiency of regeneration of in vitro leaves was not influenced by the size of the leaf attached to the petiole, but the orientation of the explant significantly influenced regeneration. Explants which responded positively were transferred to MS medium supplemented with various concentrations of TDZ and αnaphthaleneacetic acid (NAA) for shoot elongation and proliferation. The highest numbers of shoot buds (four-tofive) were achieved on MS medium supplemented with 1.38 µM TDZ and 1.62 µM NAA. Shoots were pulse-treated in half-strength liquid MS medium supplemented with 24.5 µM indole-3-butyric acid (IBA) and 5.40 µM NAA for 8 d, and then transferred to half-strength MS medium supplemented with 2.0% (w/v) sucrose, 0.02% (w/v) activated charcoal, 0.65% (w/v) agar for rooting. Rooted plants were hardened and established in soil with a ≥ 90% success rate.