The GmDREB5 from soybean enhanced salt tolerance by upregulating the transcription levels of NtP5CS and NtSODFe in transgenic tobacco.

Background: Salt stress is a significant challenge that disrupts soybean growth, development, yield, and quality. A few DREB genes in the soybean have been reported to activate downstream genes in response to abiotic stresses; however, the functions of many soybean DREB, including DREB5, remain uncharacterized. This study aimed to determine the expression of the GmDREB5 and its effects on the transcription of the NtP5CS and NtSODFe in tobacco's response to salt stress.

Methods And Results: In this study, the construct containing the soybean GmDREB5 gene was transformed into tobacco, and the expression of GmDREB5 and its downstream genes was analyzed using real-time RT-PCR. The results showed that under salt stress, the transcription levels of GmDREB5, NtP5CS, and NtSODFe increased from 8.01-fold to 87.31-fold compared to wild-type (WT) and 4.12-fold to 4.77-fold compared to under no stress conditions. The TG08 line exhibited the highest transcription levels of these genes and proline content, 2.94-fold to 4.50-fold higher compared to the WT and under non-stress conditions. The analysis in silico molecular docking showed that the DNA binding sites of the AP2 region of the DREB transcription factor interacted with the cis-acting motifs, DRE/CRT, and GT-1 of the promoter, which regulate the NtP5CS and NtSODFe.

Conclusions: These findings indicate that overexpression of GmDREB5 could enhance the transcription of NtP5CS and NtSODFe, and the transcriptional activation mechanism of downstream genes was confirmed by the in silico molecular docking. This highlights GmDREB5 as a promising candidate for improving crop salt tolerance in response to salt stress.