*Department of Biochemistry, Kurukshetra University, Kumkshetra-132 119
Department of Biotechnology, Dr. Y.S. Parmar Univesity of Horticulture and Forestry, Solan-173 230
Callus cultures of tomato were initiated from stem segment on MS medium supplemented with 1-Naphthyl acetic acid NAA (1mg/l) and BAP Benzylaminopurine (3mg/l). During subculturing concentrations of the hormones were reduced to half. Cell clumps of about 1mm in diameter were exposed to increasing concentration of polyethylene glycol (PEG) ranging from 10g/l to 100g/l for water stress tolerance. Upon incubation for 30 days, the cells which could tolerate this concentration of PEG grew to form cell clones. Selected clones were successively subcultured on the selective medium (100g/l) PEG for 8 weeks and then transferred to the normal MS medium. The selected calli when transferred from the normal to the selective medium, were capable of growing on it. Although there were differences in their growth but the pattern was sigmoidal in both the cell lines. Compared to the control, selected cells contained higher levels of soluble proteins, total and reducing sugars, free amino acids, L-proline and K+. These water stress tolerant cells also revealed enhanced activities of malate dehydrogenase, acid phosphatase and peroxidase enzymes.
