LIPID AND PROTEIN CONTENTS OF JOJOBA LEAVES IN RELATION TO SALT ADAPTATION

Jojoba (Simmondsia chinensis) seedlings were grown for two and four mo nths in a medium either without salt (control), or with 50, 100 and 15 0 mM NaCl (treated). With increasing salinity, the leaves became thick er due to an enlargement of parenchyma cells. Simultaneously ultrastru ctural changes occurred in plastids which contained swollen thylakoids , unstacked grana and large and weakly osmiophilic plastoglobuli. The osmotic pressure decreased in leaves, as well as pigment, protein and lipid contents (as referred to dry weight). Salt stress led to an incr ease of 18 and 27 kDa cytosolic polypeptides. During growth, the main polar lipids declined in leaves while saturated triacylglycerols accum ulated. A low NaCl concentration in the medium (50 mM NaCl) did not af fect the total lipid content of the leaves. Higher NaCl concentrations (100 and 150 mM NaCl) induced a severe drop in galactolipids, mainly of monogalactosyldiacylglycerol. Concomitantly phosphatidylcholine mol ecules, rich in oleic acid, accumulated.