An efficient adventitious shoot regeneration system for Zhanhua winter jujube (Zizyphus jujuba Mill.) using leaf explants.

The direct induction of adventitious shoots from leaf explants obtained from adult plants of Zhanhua winter jujube, an elite variety of Zizyphus jujuba Mill., is reported. The percentage of leaf explants producing shoots and the average number of shoots per explant were significantly improved when 10-day-old leaves were explanted onto Woody Plant Medium and maintained initially in the dark. The plant growth regulator thidiazuron (TDZ) was effective in stimulating shoot regeneration from leaf explants of Zhanhua winter jujube. The highest efficiency of shoot formation was observed with a 20-day culture in the dark on WPM containing 4.54 microM TDZ and 2.85 microM indoleacetic acid (IAA). The regenerated shoots were transferred to MS medium containing 0.89 microM benzyladenine and 5.77 microM gibberellic acid for growth. When the shoots were about 2 cm in height, they were transferred to Nitsch medium supplemented with 1.14 microM IAA and 2.46 microM indolebutyric acid to induce rooting. This system of adventitious shoot production from leaf explants of adult plants could be useful for the genetic engineering and polyploidization of winter jujube.