In Vitro Shoot Regeneration from Water Stress Tolerant Callus Culture of Tomato (Lycopersicon esculentum Mill.)

A protocol was developed for in vitro shoot regeneration from water stress tolerant callus culture of tomato cv. solan vajar on MS medium supplemented with different concentrations and combinations of various auxins and cytokinins along with 100 g/l polyethylene glycol (PEG-6000). Callus cultures of tomato were initiated from hypocotyl segment on MS medium supplemented with BAP (3mg/l) and NAA (0.5mg/l). Cell clumps of about 1mm in diameter were exposed to increasing concentration of polyethylene glycol ranging from 10g/l to 100g/l for water stress tolerance. Upon incubation for 40 days, the cells, which could tolerate this concentration of PEG, grew to form cell clones. Selected clones were successfully subcultured on the 100g/l PEG selective medium for 6 weeks and then transferred to the normal MS medium. The selected calli when transferred from normal to the selective medium, were capable of growing on it. The above selected calli were used for shoot morphogenesis. Frequency of shoot bud regeneration varied with hormonal concentrations and combinations in the medium. Among the combinations used, BAP (2mg/l) and IAA (1mg/l) combination was found to be best for higher frequency of shoot regeneration. Rooting of the regenerated shoot was found to be higher in MS medium supplemented with (0.1mg/l) NAA.