use of somaclonal variation on improvement of drought resistant lines of carrot (daucus carota l.)

abstract in order to study the effect of using somaclonal variation on production of resistant lines to water deficit conditions on carrot (daucus carota l.), an experiment was carried out in department of biotechnology of all russian research institute of vegetable crops (raas) in 2008-2009. coated seeds of four carrot cultivars which are cultivated in iran including, monarch, nantes improved, tam tam and vilmorn were collected and germinated to produce hypocotyl segments. sterliziation of hypocotyles were carried out using ethanol 70% for 30 seconds and hypochlorite solution 1% for 10 minutes. explants were placed on medium containing 2,4-d in concentration of 0.2 mg/l for callus production. for cell selection on resitance to drought, polyethylene glycol (in concentrations of 0, 5, 10, 15, 20, 25 percent) were used. nitrosoethylurea as a supermutagen was used to increase the rate of somaclonal variation in concentrations of 0, 0.5, 2 and 8 mm. results showed that callus growth and regeneration ability were considerably decreased as the concentration of selective agents increased. in the level of 20% and 25% of peg no seedling was regenerated and in concentration of 8 mm of mutagen, almost all of the calli died. results of peroxidase activity analysis and water retention content showed that the lines regenerated from media supplemented with high concentrations of polyethylene glycol that were expected to be resistant lines, had significantly higher amounts of peroxidase activity and water retention capability than the lines regenerated from lower levels.