High frequency shoot induction and plant regeneration from cotyledonary hypocotyl explants of cucumber (Cucumis sativus L.) seedlings

A method of high frequency shoot induction was established using excised hy pocotyl segments bearing cotyledons (referred to as cotyledonary hypocotyl explants) of cucumber (Cucumis sativus L.) seedlings. Adventitious shoots w ere obtained from the upper excised hypocotyls of cucumber seedlings incuba ted on Murashige and Skoog (MS) medium containing 2.0 mg/L zeatin. The effe cts of cotyledon size and hypocotyl length of seedlings on shoot organogene sis were also examined. A higher frequency (80-90 %) of adventitious shoots was obtained from explants of 3- and 5-day-old seedlings with either 1 cot yledon or 2 half-cotyledons, and a short hypocotyl length (2 mm). However, explants with long hypocotyls and 2 cotyledons produced fewer shoots. Adven titious shoots from cotyledonary hypocotyl explants were removed and rooted in MS medium containing 1.0 mg/L IAA. The rooted plantlets developed into normal plants after acclimatization to ambient humidity levels.