Overexpression of transcription factor SlWRKY28 improved the tolerance of Populus davidiana x P. bolleana to alkaline salt stress

Background WRKY transcription factors (TFs) have been suggested to play crucial roles in the response to biotic and abiotic stresses. This study is the first to report the alkaline salt regulation of the WRKY gene. Results In this study, we cloned a WRKY gene (SlWRKY28) from theSalix linearistipularisand then transferred to thePopulus davidianaxP. bolleanafor expression. Sequence analysis on the transcriptome ofSalix linearistipularshowed the significant up-regulation of WRKY gene expression in response to salt-alkali stress in seedlings. Our data showed that SlWRKY28 localized to the nucleus. Furthermore, the expression of theSlWRKY28from female plants increased with saline-alkali stress according to the northern blot analysis results. The results of 3,3 '-Diaminobenzidine (DAB) staining showed that hydrogen peroxide (H2O2) concentration was lower under stress, but ascorbate peroxidase (APX) enzyme activity was significantly higher in the overexpressed plants than that in non-transgenic (NT) plants. Conclusions We found out theSlWRKY28induced regulation of the enzyme gene in the reactive oxygen species (ROS) scavenging pathway is a potential mechanism for transgenic lines to improve their resistance to alkaline salt. This study shows theoretical and practical significance in determiningSlWRKY28transcription factors involved in the regulation of alkaline salt tolerance.