Abstract: Transcription factor gene GmWRKY21 was introduced into two soybean varieties ‘Zhechun No.5’ and ‘Zhonghuang 13’ via Agrobacterium-mediated transformation system. Embryonic tips jointed with one piece of cotyledon severed as explants in this study. Transformation events were confirmed using target gene-specific and construct-specific PCR analysis. Transgenic plants showed significantly lower electric conductivity than their non-transgenic controls before and after chilling treatment. Better low temperature tolerability of transgenic plants was confirmed after recovered for days： the transgenic plants grew normally, while their controls died in 7 to 10 days after chilling treatment. These results indicated that GmWRKY21 gene had been introduced into soybean genome and it's likely that this gene participated in response to low temperature stress, and finally led to an improved cold tolerance in soybean．

Key words: soybean, GmWRKY21, low temperature, Agrobacterium-mediated transformation