In vitro plantlet regeneration from hypocotyl explants of Stellaria longipes (Caryophyllaceae)

An in vitro regeneration protocol for Stellaria longipes Goldie was develop ed using young hypocotyl explants. Optimal regeneration was obtained using Murashige and Skoog (MS) basal medium supplemented with 0.5 mu M N-6-benzyl adenine and 1 mu M indole-3-butyric acid. Three different patterns of shoot regeneration were observed: (i) "direct shoot" formation within 3-5 days o f inoculation, (ii) nodular structures appeared followed by shoot formation , and (iii) callus formation followed by the appearance of shoots. Histolog ical observation revealed that cells within the central vascular cylinder o f the hypocotyl were responsible for shoot organogenesis. Shoot production was not synchronous or uniform among explants. A more synchronous shoot pro duction was obtained by excising the direct shoots or by wounding the nodul ar structures. Excision and wounding increased the regeneration capability of the explants. Regenerated shoots were readily rooted in MS medium lackin g growth regulators and were successfully transferred to greenhouse conditi ons. These showed morphology consistence with greenhouse-grown plants.