RESUMO
As soil salinity constitutes a major threat to agriculture in the world, to cope with this problem, much emphasis has been focused on the response mechanism of halophytes or salt-tolerant species to salinity stress. In the present study, C. album was treated with long-term NaCl and KCl stress, then several parameters were assayed in leaves as follows: inductively coupled plasma atomic emission spectrometry (ICP-AES) was employed to measure the K, Na content; semi-quantitative RT-PCR was used to investigate the expression level of three genes which were related to ion transport on the vacuolar membrane-NHX, VP1 and VAP-C. In addition, the mechanism for the effect of different salinity on K, Na content was preliminarily discussed. The results were as follows: (1) Under lower concentration of NaCl stress, C. album had a preferential uptake of potassium and exclusion of sodium, and thus maintained a low concentration of sodium in cells of the leaf; (2) Under higher concentration of NaCl (300 mmolx L(-1)), C. album was able to tolerate excessive amounts of sodium in cells and kept the higher K/Na ratio in cytoplasm by compartmentalizing Na ions into the vacuole via ion transporter system located on vacuole membrane, (3) Much K ions and total ions (including sodium and potassium) may be responsible for, at least partial, the intolerance of C. album to high concentration of KCl. In conclusion, C. album could tolerate high concentration of NaCl stress, accompanied by high ability to accumulate Na+ in leaves. These results could contribute to the further investigation of this promising species, e.g., amending saline soil.
