Comparative in vitro shoot organogenesis and plantlet regeneration in tomato genotypes

Abstract

A study was conducted for achieving high frequency regeneration in tomato genotypes as a pre-requisite for genetic transformation. Regeneration efficiencies were compared in five tomato genotypes using hypocotyl and cotyledon segments as explant source. Two cytokinins, namely BAP (0.0 to 3.0 mg l-1) in combination with or without kinetin (0.5 and 1.0 mg l-1) were used in Murashige and Skoog’s medium. Irrespective of genotypes, 2.0 mg l-1 BAP supplementation gave the best response for both explants. The highest frequency shoot regeneration (96.6 and 92.2%) as well as the maximum number of shoots per explant (10.2 and 8.4) was obtained from the hypocotyl and cotyledon explants, respectively in genotype H-86. The cultures on this medium were green and showed good shoot bud organogenesis. The individual shootlets were separated and inoculated on growth regulator-free MS medium. After two weeks of root induction, the individual plantlets were transferred to glass jars filled with autoclavable polyproplylene (PP) caps filled with sterile peat : vermiculite (2:1). This hardening strategy lead to over 90.0% plant survival at greenhouse stage. The results suggested that of the two explants tested, hypocotyl segment was more responsive compared to cotyledon segment. The order of genotype response was H-86> H-24> DVRT-1> Sel-7> DVRT-2 with regards to shoot organogenesis and multiplication frequency.