Exploring Birch Salt Tolerance Using Gene Regulatory Network Highlighting Hormone Signaling, Reactive Oxygen Species Scavenging, and Ion Homeostasis.

Salt stress presents a formidable challenge for plant survival, yet the intricate regulatory networks dictating salt-tolerant gene expression remain elusive. This research delineates a gene regulatory network (GRN) in birch (Betula platyphylla) under salt stress, utilizing a partial correlation coefficient-based algorithm. The GRN comprises three hierarchical layers: the top layer with 5 transcription factors (TFs), the middle layer with 22 TFs, and the bottom layer encompassing 345 structural genes, totaling 1458 regulatory interactions. Validation through ChIP-PCR and qRT-PCR confirmed approximately 87.5% and 68.7% accuracy of predicted interactions in the top-middle and middle-bottom layers, respectively. The GRN underscores the pivotal roles of abscisic acid (ABA), jasmonic acid (JA), and cytokinin (CK) signaling pathways, emphasizing ROS scavenging and ion homeostasis as critical for salt tolerance. Among the top layer TFs, BpERF105 demonstrated superior salt tolerance, positioning it as a key regulatory element. This study posits that birch's salt tolerance is orchestrated through a regulatory homeostasis mediated by intricate TF-TF and TF-DNA interactions, providing profound insights into the molecular underpinnings of plant salt stress responses.