Anatomical observations of adventitious bud regeneration from leaf explants of Ziziphus jujube Mill. 'Huizao'

The histological process of adventitious shoot regeneration from the leaf explants of Zizyphus jujuba 'Huizao' was reported in this study. This is the first report on the detailed histological process of direct shoot regeneration from leaf explants in Z. jujube. Shoot regeneration was obtained from woody plant medium (WPM) supplemented with 2.27 mu M thidiazuron (TDZ), 1.07 mu M alpha-naphthalene-acetic acid (NAA) and 2.94 M silver nitrate (AgNO3) for 10 days in the dark followed by 3 weeks at a 14 hours photoperiod. The adventitious buds mostly formed from leaf veins and petioles, and the further histological studies revealed that there were multiple vascular bundles around leaf veins and the adaxial side of explants, and the adventitious buds directly originated from the parenchymatous cells around the vascular bundles without the intervening callus phase. After 3 days of culture, the parenchymatous cells started dividing and meristemoids formed thereafter. The meristematic cells continued division and subsequently gave rise to bud primordia. Well-developed shoot buds through direct organogenesis was achieved after 20 days of culture.