Changes in osmolites contents, lipid peroxidation and photosynthetic pigment of Aeluropus lagopoides under potassium deficiency and salinity

Potassium, the most abundant cation in plant cells, is responsible for numerous physiological functions. In saline environment, similarity of Na+ and K+ causes an unbalance in K+ uptake and disorder in the its functions. In the present research, changes of four biochemical parameters (proline, glycinebetaine, photosynthetic pigments and malondialdehyde) have been investigated in Aeluropus lagopoides seedling under salinity and potassium deficiency. Sterile seeds had been cultured on modified Murashige-Skoog containing 0, 1.75 or 100 mM potassium, with or without 600 mM NaCl for 30 days. The results showed that maximum proline content was observed in root and shoot by 600 mM NaCl + 1.75 mM K+ treatment. Also in this treatment, amount of carotenoids and chlorophyll a was more decreased. Potassium deficiency caused to reduced MDA and chlorophyll b content. The highest amount of glycinebetaine was measured in the presence of 600 mM NaCl in the company of 100 mM K+. It can conclude that chlorophyll oxidation was occurred in K+ deficiency because of increasing lipid peroxidation and disruption of protein-pigment complexes. The accumulation rates of two osmolite in different organ was shown that in A. lagopoides proline and glycinebetaine play more important role in osmotic adjustment of the shoot and root, respectively.