DEVELOPMENT OF AN EFFICIENT AND REPRODUCIBLE IN VITRO REGENERATION SYSTEM IN CARROT (T-29)

Embryogenic calli were induced from stem segment of carrot (Daucus carrota L.) cultivar T-29 when cultured on callus induction (CI) medium containing MS salts, Myo-inositol, B5 vitamins, 3 mgL^-1 2,4-D, 1 mgL^-1 Kinetin and 20 gL^-1 sucrose. Somatic embryos were developed from calli upon transferring to MS medium, containing 30gL^-1 sucrose without any additional plant growth regulators PGRs (MS₂ medium). To enhance the number of mature somatic embryos and plant regeneration, the induced calli were pretreated for two weeks on a modified CI medium that lacks 2,4-D but contains kinetin (0.6 mgL^-1). The production of somatic embryos and shoots increased 10-fold in pretreated calli when cultured on MS₂ medium compared with calli without pretreatment. The sucrose starvation treatment for two weeks, using modified CI medium that contains 20 gL^-1 sucrose and reduced levels of kinetin, results in improved regeneration. Similarly, a greater number of mature somatic embryos and shoots primordia when transferred to a medium carrying 30 gL^-1 sucrose were recovered. Thus, temporary sucrose and kinetin starvation remarkably enhanced plant regeneration that may be valuable in future experiments of genetic transformation.