GmHKT1;4, a novel soybean gene regulating Na+/K+ ratio in roots enhances salt tolerance in transgenic plants

Salt is an important factor affecting the growth and development of soybean in saline or alkaline soil. The aims of the present study were to identify and functionally analyse the soybean GmHKTs gene family, and to explore their roles under NaHCO₃ and NaCl stresses. The GmHKTs gene family were isolated from soybean using genome sequence information. The GmHKTs gene family were further analysed for the structure and phylogenetic relationship. The expression patterns of soybean GmHKTs genes under NaHCO₃ and NaCl stresses were analysed via quantitative real-time PCR. As a result, the expression level of GmHKT1;4 was extremely up regulated in root under each treatment. Overexpression of GmHKT1;4 significantly enhanced the tolerance of transgenic tobacco plants to NaHCO₃ and NaCl stresses, compared with null plants. The overexpressed transgenic plants of this gene accomulated more K⁺ and less Na⁺ under salt stress, compaired with null plants. Our findings suggest that GmHKT1;4 plays an important role for regulation Na⁺/K⁺ ratio in roots under alkaline (NaHCO₃) and saline (NaCl) stresses.