Abstract: A GmWRKY6 gene from WRKY transcription factor family members from soybean was cloned from salt stress RNA-Seq data. Sequence analysis showed that the gene contained an open reading frame (ORF) of 1674 bp and 557 encoding amino acids. The GmWRKY6 protein contained a conserved WRKY domain and a C2H2 zinc finger motif, belonged to group IIb WRKY transcription factor. Analysis of gene expression pattern showed that the expression level of GmWRKY6 gene is highest in the root and was induced by salt stress. Plant overexpression vector of the GmWRKY6 gene was constructed and 7 positive T₀ transgenic Lotus japonicus plants were obtained. The salt resistance of T₁ transgenic lines was further analyzed, after exposure to 200 mmol·L^-1 NaCl for 14 days; transgenic lines grew well while the wild type were stunted with dry foliage. Proline and chlorophyll content in transgenic lines were significantly higher than wild plants, while the MDA content and the relative permeability of plasma membrane were significantly lower than that of wild plants. In addition, the sodium ion content in transgenic lines was significantly lower than wild plants under salt stress, while the potassium content was significantly higher than that of wild plants. These results showed that over expression of the soybean GmWRKY6 gene can significantly enhance the salt resistance of L. japonicus.

Key words: soybean, WRKY transcription factor, cotyledonary node transformation, Lotus japonicus, salt tolerance