In Vitro Selection for Salt Tolerance in Brassica juncea L. Using Cotyledon Explants, Callus and Cell Suspension Cultures

Salt-tolerant Brassica juncea L. cell lines or plants have beenselected by screening callus pieces, cell suspension culturesand cotyledon explants in vitro on high concentrations of NaCl.Callus-based selection was unsatisfactory, as only two out ofseven isolated clones retained tolerance after 3 months of subcultureon NaCl-free medium. Selections made via plated cell suspensionswere found to be more stable for salt-tolerance. AH selectedtolerant cell lines, however, failed to regenerate plantlets.A third selection method, employing cotyledon explants was basedon their high potential for regenerating multiple shoots. Outof a total of 2620 explants cultured on high salt media, threesurvived, showed sustained callus proliferation and each regeneratedone shoot. The salt-selected shoots withstood the stabilitytest after 3 months of growth and axillary bud multiplicationon NaCl-free medium. While one of these somaclones was morphologicallyabnormal and sterile, the other two could be reared to maturitywith normal seed set. Brassica juncea, tissue culture, in vitro selection, salt-tolerance, plant regeneration