IMPACT OF POLYETHYLENE GLYCOL INDUCED WATER STRESS ON CALLI GROWTH AND ACCUMULATION OF PROLINE IN Capsicum spp.

Abstract

In this research, in vitro studies were apprehended on the Capsicum spp. Seedlings of five genotypes of Capsicum were grown on agar solidified MS (Murashige and Skoog) medium. Prior to inoculation of seeds in the medium, seeds were pretreated with fungicide 0.1% rekazim (carbendazim) and then surface sterilized with absolute alcohol followed by 10% NaOC1. The cultures of the seeds germinated initially at dark at 27 ± 1 oC for ten days and then in light under 16 h photoperiod at 25 ± 2oC. Cotyledonary leaf and nodal segment explants from three weeks old seedlings were excised in approximately 0.5 cm of length. These explants were cultured on MS basal medium for callus formation. To find out the effect of water stress or lowering osmotic potential conditions in the medium on the callus formation and response of the biomass induction, polyethylene glycol (PEG 6000) in 0 g/L, 20 g/L, 40 g/L, 60 g/L and 80 g/L concentrations were added to the MS medium. Biomass measurement of calli (size and weight) was realized in three weeks interval from the callus inoculation. In the normal MS medium, biomass formation was very fast but when PEG used, for changing the osmotic potential of the MS medium the biomass formation decreased because of the water stress conditions. Proline content gradually increased as the PEG concentration increased. At short duration (20 days after treatment with PEG) of water stress genotype G3 (SRC02) recovered at high water stress (60 g/L of PEG) in respect of callus size and weight as well as in proline accumulation. At prolonged stress period (40 days after treatment with PEG), G1 (CO611) and G4 (SRC05) showed better performance at severe stress (60 g/L of PEG) which correlates with the accumulation of proline. As G1 (CO611), G3 (SRC02) and G4 (SRC05) showed tolerance to water stress at different duration by showing comparatively better biomass changing of calli and proline accumulation, these genotypes could be selected for getting drought tolerant calli.