Organogenesis during plant regeneration in cotyledon culture of Trifolium michelianum Savi

Shoots of <em>Trifolium michelianum</em> 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 µM. 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.

EMBRYOGENESIS IN EGGPLANT COTYLEDON CULTURE

Eggplant (Solanum melonga L.) cotyledons were used to form somatic embryos for somaclonal induction and for selection of salt tolerant genotypes in a genetic improvement program. Naphthalene acetic acid at concentrations ranged from 5 uM to 85 uM induced embryogenesis when cultures were incubated under 16 hrs of light photoperiod. NAA was the only growth regulator required, and the addition of kinetine and benzyl adenine inhibited embryo formation. High frequency embryogenesis formed in 2 week old cotyledons when cultured on a medium supplemented with 43 uM NAA. Data showed that varieties varied in their embryogenesis potential and that cotyledons were the most responsive tissue. Somatic embryos germinated into plantlets when transferred into media without any growth regulators. Somatic embryos were plated on germination media supplemented with Kuwait brackish water to increase the total dissolved salts in the medium from 4,770 ppm to 30,000 ppm in seven equal increments. Brackish water at all concentrations caused embryos to revert into profuse callus growth.