Production of sodium-chloride-tolerant Brassica juncea plants by in vitro selection at the somatic embryo level.

Somatic embryos, developed from hypocotyl segments of light-grown seedlings of Brassica juncea cv RLM198, were subjected to selection at varying concentrations of sodium chloride (NaCl). Plants were developed from proliferated somatic embryos selected on NaCl-containing medium. The selections were characterized for salt tolerance, esterase isozyme pattern, and proline accumulation. It has been found that: (i) selected tolerant lines showed better root growth, shoot growth, and fresh weight accumulation on salt-containing medium when compared to the control; (ii) salt tolerance was transmitted to the next generation in seed progeny of tolerant plants grown in the absence of exposure to salt; (iii) both the starting material and the tolerant selections accumulated proline, even when grown in salt-free medium. On salt-containing medium, however, the differences in accumulated proline between the control and tolerant lines became more pronounced, and (iv) the patterns of esterase isozymes of two tolerant selections were similar but distinctly different from that of the parental control.