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

Jojoba (Simmondsia chinensis) seedlings were grown for two and four months in a medium either without salt (control), or with 50, 100 and 150 mM NaCl (treated). With increasing salinity, the leaves became thicker due to an enlargement of parenchyma cells. Simultaneously ultrastructural 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 increase of 18 and 27 kDa cytosolic polypeptides. During growth, the main polar lipids declined in leaves while saturated triacylglycerols accumulated. A low NaCl concentration in the medium (50 mM NaCl) did not affect 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 molecules, rich in oleic acid, accumulated.