Thidiazuron and Explant Type Effects on High-frequency In Vitro Mass Propagation of Cherry Tomato

Cherry Tomato is one of the most important vegetable crops cultivated for export in Egypt. In vitro culture response was assessed in tomato (Solanum lycopersicum L. var. cerasiforme) cv. (Summer Cherry) for optimum callus induction and plantlet regeneration. Callus induction was achieved within eight to 12 days directly on the cut surfaces of hypocotyl, cotyledon and leaf disc explants cultured on Murashige and Skoog (MS) basal medium supplemented with various concentrations of Thidiazuron (TDZ)] and benzyl adenine (BA) alone, but not in hormone free-medium. The highest callusing index (3.9 and 3.7) was obtained on hypocotyl explants cultured on MS medium supplemented with TDZ(1.0 and 2.0 mgl^-1) followed by an index of 3.5 obtained from the same explant by using 0.5mgl^-1 BA. However, for the leaf disc explants, the highest callusing index (3.1) was obtained on MS medium supplemented with BAat 2.0 mgl^-1. After 8 weeks of culture, organogenesis was observed only on the explants cultured on medium containing different concentrations of TDZ and BA. The best shoot formation (93%) was obtained from leaf disc explant callus induced on MS medium containing TDZ. The highest number (13.4) of shootsexplant^-1 was found when cotyledon explant callus was sub cultured on MS medium supplemented with 2.0 mgl^-1 TDZ. Half strength of MS was found to be the best rooting medium, however, addition of IAA at 1.0 mgl^-1 and IBA at 2.0 mgl^-1 were found necessity to induce highest number of roots (22.5) and longer roots (11.0 cm), respectively. Acclimation of in vitro rooted plant is important for testing the post culture behavior of tissue culture regenerated plants. Cherry tomato derived from different explant sources under different concentration of TDZ and BA were not significantly different in their vegetative characters to those obtained from seed. However number of (raceme plant^-1, flower raceme^-1, fruit raceme^-1, fruit plant^-1) which produced by seed-derived plants was significantly less than those derived from in vitro propagated plants. This protocol would be valuable to create somaclonal variation and develop transgenic approaches for varietal improvement of cherry tomato.