International Journal of Biotechnology & Biochemistry

In vitro response was assessed in two genotypes of tomato (Lycopersicon esculentum Mill.) viz., Punjab Upma and IPA-3 for direct shoot regeneration from cotyledon explants. The explants were excised from in vitro tomato seedlings and cultured on MS medium supplemented with different concentrations and combinations of plant growth regulators. Direct regeneration was significantly influenced by the genotype, plant growth regulator and combinations. The MS medium supplemented with Kinetin (0.5 mg/l) and (BAP 0.5 mg/l) was found optimum for inducing direct shoot regeneration and number of shoots per explant from cotyledonary explants on this medium, shoot regeneration per cent in Punjab Upma and IPA-3 per cent was recorded to be highest i.e (92.49) and (83.48) respectively. Besides this, average number shoots per explant was also highest i.e (4.78) in case of Punjab Upma and (4.10) in case of IPA-3. A significant decline was observed in percent shoot regeneration and average number of shoots per explant with increase in the hormonal concentration. Shoots were obtained and transferred to the elongation medium (MS + BAP 0.3 mg/l). Hundred per cent rooting was induced in separated shoots upon culturing on MS and ½ MS basal media. Hardening on moist cotton showed maximum plantlet survival rate in case of both genotypes. After hardening, plants were transferred to soil. Thus, a tissue culture base line was established in tomato for obtaining direct regeneration using cotyledons as explants.