The GRAS transcription factor BpGRAS34 functions as a positive regulator of salt stress response in Betula platyphylla.

Plant-specific GRAS transcription factors play crucial roles in the response to abiotic stresses, yet many of GRASs remain functionally uncharacterized. In this study, the GRAS transcription factor BpGRAS34 from Betula platyphylla was identified and characterized for its role in responding to salt stress. BpGRAS34 is a nuclear-localized protein that possesses transcriptional activation activity. BpGRAS34 overexpression and knockout plants were generated to investigate abiotic stress tolerance through both gain-of-function and loss-of-function analyses. The results indicate that BpGRAS34 enhances salt stress tolerance by upregulating the expression of key genes, including pyrroline-5-carboxylate synthase (P5CS), peroxidase (POD), and superoxide dismutase (SOD). This upregulation leads to increased proline levels and improved reactive oxygen species (ROS) scavenging ability. Additionally, BpGRAS34 specifically binds to the GARE motif with the sequence 'AAACAGA'. As a transcriptional activator, BpGRAS34 regulates the expression of BpDOF9, BpOYE1, and BpnsLTP1 by binding to their GARE motifs. This interaction promotes physiological responses crucial for enhancing salt stress tolerance, including proline biosynthesis and ROS scavenging pathways. Overall, these findings suggest that BpGRAS34 plays a crucial role in mediating abiotic stress tolerance by inducing the expression of stress-related genes, thereby enhancing proline levels, osmotic potential, and ROS scavenging capacity. Therefore, this study provides a theoretical foundation and identifies a candidate gene for the genetic improvement of B. platyphylla.