Thellungilla halophila is more adaptive to salinity than Arabidopsis thaliana at stages of seed germination and seedling establishment

Thellungiella halophila is a salt tolerant relative of Arabidopsis thaliana with high genetic and morphological similarity. In the present study, effects of salinity on germination and seedling growth of T. halophila and A. thaliana were compared. The present results showed that the salinity inhibited seed germination in both species. Unexpectedly, percentages of seed germination in A. thaliana were higher than T. halophila in a range of 0?C200?mM NaCl. Seeds of both species could not germinate when the concentration of NaCl was over 200?mM. However, when compared with A. thaliana, seeds of T. halophila did not suffer ion toxicity, as evidenced by the higher final germination rate after ungerminated seeds pretreated with NaCl were transferred to distilled water. Seedlings of T. halophila were more salt tolerant than those of A. thaliana, e.g., seedlings of T. halophila had better plant growth (root length, fresh and dry mass), higher chlorophyll content, less MDA content and higher proline content and K⁺/Na⁺ ratio under salinity. These results indicate that T. halophila is more salt tolerant than A. thaliana during both seed germination and seedling stages and explain why A. thaliana is excluded from saline locations and T. halophila can survive in saline soils.