Abscisic Acid accelerates adaptation of cultured tobacco cells to salt.

Adaptation of tobacco (Nicotiana tabacum L. var Wisconsin 38) cells to NaCl was accelerated by (+/-) abscisic acid (ABA). In medium with 10 grams per liter NaCl, ABA stimulated the growth of cells not grown in medium with NaCl (unadapted, S-0) with an increasing response from 10(-8) to 10(-4) molar. ABA (10(-5) molar) enhanced the growth of unadapted cells in medium with 6 to 22 grams per liter NaCl but did not increase the growth of cells previously adapted to either 10 (S-10) or 25 (S-25) grams per liter NaCl unless the cells were inoculated into medium with a level of NaCl higher than the level to which the cells were adapted. The growth of unadapted cells in medium with Na(2)SO(4) (85.5 millimolar), KCl (85.5 or 171 millimolar), K(2)SO(4) (85.5 millimolar) was also stimulated by ABA. ABA (10(-8)-10(-4) molar) did not accelerate the growth of unadapted cells exposed to water deficits induced by polyethylene glycol (molecular weight 8000) (5-20 grams per 100 milliliters), sorbitol (342 millimolar), mannitol (342 millimolar) or sucrose (342 millimolar). These results suggest that ABA is involved in adaptation of cells to salts, and is not effective in promoting adaptation to water deficits elicited by nonionic osmotic solutes.