The Effect of Salinity on Light and Dark CO2-Fixation of Salt-Adapted and Unadapted Cell Cultures of Atriplex and Tomato

Abstract

The effect of salinity on light and dark CO2,-fixation was determined in cells of A triplex portulacoides and tomato (Lycopersicon esculenturn Mill.) grown in culture. CO2,-fixation of tomato cells was also determined in cultures adapted to mannitol and polyethylene glycol (PEG). Salinity up to 400 mM NaCI in the case of A triplex and up to 50 mM in the case of tomato enhanced the rate of light-induced CO2,-flxation in unadapted cells. Higher salt concentrations led to a marked decline in CO2-flxation in both species. In salt-adapted A triplex cells no decline in the rate of light CO2,-flxation was seen even at 500 mM NaCl. Dark CO2,-fixation was approximately 40% and 80% of the light fixation in control cell cultures of A triplex and tomato, respectively. No enhancement in dark CO2,-flxation was seen as salinity was increased, but a decline was found at similar salt concentrations that decreased fixation in the light. Mannitol-and PEG-adapted tomato cells fixed CO2, at somewhat lower rates than the control cells in the light but not in the dark.