Growth characteristics of NaCl-selected and nonselected cells of Nicotiana tabacum L.

Abstract

A cell line of Nicotiana tabacum L. var. Wisconsin 38 was selected (S-10 cells) which is capable of growth in medium containing 10 g liter⁻¹ NaCl. The fresh and dry weights of S-10 cells at stationary phase in medium containing 10 g liter⁻¹ NaCl were about 60 and 100% respectively, of that of S-10 cells grown without NaCl. When cells normally maintained in the absence of the salt (S-0 cells) were transferred to medium containing 10 g liter⁻¹ NaCl, they underwent a 14-day lag period before growth could be detected and they reached stationary phase 36 days after inoculation compared to 14 days for S-10 cells. At stationary phase, fresh and dry weights of S-0 and S-10 cells were the same in the presence of salt. The S-0 cells exhibited a reduced growth rate once growth began in medium with 10 g liter⁻¹ NaCl. The cell mass doubling time of S-0 cells in medium with 10 g liter⁻¹ NaCl was 4 days compared to 1.2 days for these cells grown in the absence of the salt and 1.6 days for S-10 cells grown in medium with 10 g liter⁻¹ NaCl. The resistance of the salt-selected cells was stable in the presence of the salt. However, after 5 cell mass doublings following transfer into medium without NaCl, these cells lost their resistance to salt and responded to NaCl like the cell population (S-0 cells) which had not been selected for growth on NaCl.