Over-expression of GmHAL3 modulates salt stresses tolerance in transgenic arabidopsis

The halotolerance protein HAL3, also known as SIS2, is a yeast protein that regulates the cell cycle and tolerance to salt stress through inhibition of the Ppz1 type 1 protein phosphatase. Although the roles of HAL3 have been demonstrated during the growth, development, and stress adaptation of Arabidopsis thaliana and Nicotiana tabacum, the function of HAL3 in other plant species, including soybean (Glycine max), has not been elucidated. In this study, GmHAL3a and GmHAL3b were isolated from Glycine max, and their roles were analyzed. GmHAL3a and GmHAL3b transcripts were detected in the roots, stems, leaves and seeds, with higher levels in the roots, and were induced by sodium chloride (NaCl), lithium chloride (LiCl), sorbitol, cold and ABA treatment. Overexpression of GmHAL3a or GmHAL3b in Arabidopsis accelerated the onset of flowering and resulted in more vigorous seed germination and increased tolerance to NaCl, LiCl, and sorbitol stress in seedlings, compared with wild type (WT) and empty vector control (VC) plants. Transgenic Arabidopsis plants accumulated proline and eliminated superoxide radical (O2−) in response to the stress. In addition, transcription levels of the stress-related genes RD22 and P5CS1 were substantially higher in transgenic Arabidopsis than in WT and VC plants. Taken together, the data indicate that GmHAL functions as a positive regulator of the response to salt, lithium cations and sorbitol stress.