In vitro selection and characterization of water stress tolerant cultures of bell pepper

Callus of bell pepper (CaΨcum annuum L.) was initiated from hypocoty1 on MS medium supplemented with NAA (0.5mg⁻¹) and BAP (0.2mg⁻¹). For proliferation of callus the hormone concentrations were reduced to half. Cell clumps of about 1mm diameter were exposed to increasing concentration of polyethylene glycol (PEG) ranging from 10 g⁻¹ to 100 g⁻¹ for water stress tolerance. Upon incubation for 30 days, the cells, which could tolerate this concentration of PEG, grew to form calli. Selected calli were further subcultured on to the selective medium (100 g⁻¹) PEG for 8 weeks and then transferred to normal MS medium for proliferation. The selected calli when transferred from the normal to the selective medium, were capable of growing on it. Although, there were difference in their growth, the pattern was sigmoidal in both the cell lines. Compared to the control, selected cells contained significantly higher levels of soluble proteins, total sugars, reducing sugar, and free amino acids. The water stress tolerant cells also revealed enhanced activities of enzymes, malate dehydrogenase, alkaline invertase, NADP+ – isocitrate dehydrogenase, aspartate amino transferase, glutamate pyruvate transaminase and acid phosphatase.