Cloning and Expression of FmDREB1B in Fragaria mandschurica Staudt

Objective Involvement of DREB1B in the cold resistance of Fragaria mandschurica Staudt was studied.

Methods Full length cDNA of DREB1B in F. mandschurica was cloned by RT-PCR and analyzed bioinformatically. The sequence of FmDREB1B promoter was cloned with cis-acting elements predicted. GUS vector was constructed to be transiently transformed into tobacco leaves for staining and enzyme activity determination. Relative expression of FmDREB1B was analyzed using RT-qPCR.

Results The cDNA of FmDREB1B (GenBank accession number: MN738503.1) was 690 bp in length encoding 229 amino acids that included a conserved AP2 DNA-binding domain. The amino acids encoded by FmDREB1B had the highest homology with FvDREB1B. The FmDREB1B promoter (GenBank accession number: MN933919.1) contained several cis-acting elements associated with hormones and adversity stress responses. The transformation of pFmDREB1B::GUS into tobacco leaves resulted in the transcriptional activity of the promoter. DREB1B expressed in various tissues of F. mandschurica that peaked to be 22.58 times of 0 h after 6 h at 4 ℃. A 6 h ABA （Abscisic Acid）treatment produced a peak expression 15.28 times the original. In contrast, in F. ananassa Duch, the highest expression of DREB1B was 5.41-folds of that at 0 h under the same treatment at 4 ℃ for 6 h, while the ABA treatment resulted in merely 4.64-folds of 0 h.

Conclusion  The finding that DREB1B is involved in the low-temperature response, combined with its initial identification and functional characterization, lays a foundation for further research into its role in the cold tolerance mechanism of F. mandschurica.