Organogenesis during plant regeneration in cotyledon culture of Trifolium michelianum Savi.

Shoots of Trifolium michelianum Savi. could be induced directly from the cotyledonary petiole or through petiole-derived callus on EC6 medium (Mahewswaran and Williams 1984) supplemented with BAP at 4.4, 8.8 and 22.2 mu M. The mode of caulogenesis highly depended on cytokinin concentration in the medium. Most of the shoots regenerated into mature plants when transplanted to half-strong MS (Murashige and Skoog 1962). The time of caulogenic determination was set for the first day of culture. The induction of determination for caulogenesis was accompanied by the loss of competence toward root formation. SEM studies revealed that caulogenesis was restricted to the distal end of the cotyledonary petioles, very close to but not at the site of excision. The sites of shoot regeneration were limited to abaxial and lateral surfaces of the petioles.