In vitro direct plant regeneration protocol for tomato genotypes

A high frequency direct plant regeneration method was developed for four tomato genotypes, viz., Castle Rock, Punjab Upma, VFN-8 and IPA-3. Cotyledons of 8-day-old in vitro grown seedlings of the four genotypes were excised and cultured onto Murashige an Skoog (MS) medium supplemented with different concentrations and combinations of BAP and kinetin. The frequency of plant regeneration and number of shoots per explant was influenced by the genotype and concentration of growth regulators. Among the genotypes tested, IPA-3 recoded the maximum plant regeneration (95.14%) followed by Punjab Upma (93.13%), Castle Rock (90.02%) and VFN-8 (82.09%). Among the different media compositions tried maximum average plant regeneration (90.14%) and number of shoots (6.17) were obtained using MS medium supplemented with BAP 2.0 mg l⁻¹ and kinetin 1.0 mg l⁻¹. With either decrease or increase from the optimum level, decline in percent plant regeneration as well as number of shoots per explant was recorded. The shoots when attained approximately 2 cm height were transferred to the half-strength MS medium, which led to simultaneous shoot elongation as well as root formation. All the shoots recorded 100% rooting and were subsequently transferred to poly bags containing FYM: sand:soil (1:1:1) and kept in glasshouse for acclimatization.