Efficient and simple plant regeneration via organogenesis from leaf segment cultures of persimmon (Diospyros kaki Thunb.)

An efficient and simple plant regeneration system via organogenesis from leaf segments of persimmon (Diospyros kaki Thunb.) cultivars 'Fuyu' and 'Nishimurawase' has been developed. The regeneration capacity was influenced by the culture vessels, gelling agents, plant growth regulators, and light conditions. Leaf explants taken from in vitro shoots were cultured on a modified Murashige and Skoog medium (MS1/2N) for 16 wk without transfer to fresh medium. Adventitious shoots appeared after 4 and 8 wk in culture of 'Nishimurawase' and 'Fuyu' tissues, respectively. The culture of leaf explants in Erlenmeyer flasks with medium containing 4 g l^-1 agar enhanced shoot formation in comparison to media with increased agar concentrations. Optimal shoot regeneration was obtained with 5 mg l^-1 (22.8 μM) zeatin and 0.1 mg l^-1 (0.05 μM) indole-3-butyric acid (IBA) for 'Nishimurawase', and 10 mg l^-1 (45.6 μM) zeatin and 0.1 mg l^-1 (0.05 μM) IBA for 'Fuyu'. Shoot regeneration frequencies in both cultivars were 100%, and shoot numbers per explant reached up to 9.2 for 'Nishimurawase' and 2.2 for 'Fuyu'. Dark incubation during the first 4-5 wk was the most effective condition to successfully influence shoot regeneration in both cultivars. While dark incubation was essential for adventitious shoot formation by 'Fuyu', it was only slightly beneficial to 'Nishimurawase'. More than 80% of the regenerated shoots rooted within 4 wk on hormone-free MS1/2N medium after having been dipped for 30 s in 250 mg l^-1 (1.1 mM) 1BA solution.