Following ultraviolet mutagenesis, we have isolated two Na(+) dependent variants from haploid suspension cultures of soybean cells. No selection was used in the isolation procedure. These cells cannot grow in 1 mM Na(+) but can grow in 17 mM Na(+). The strains also grow in 33 or 65 mM Na(+), concentrations in which the parent cell line dies. [(22)Na] was used to measure the accumulation of Na(+) by parent and variant cell lines. Two- to three-fold less Na(+) is retained by the variant cell lines.