OsbZIP27 coordinates with OsHUB1 and OsHUB2 to modulate drought tolerance in rice

Zuntao Xu, Yachun Yang, Fei Zhang, Hao Li, Hui Ma, Wenge Wu, Yong Ding

J Genet Genomics; 2025 Feb; 52(2):168-178. doi: 10.1016/j.jgg.2024.11.016.

Abstract

Histone H2B ubiquitination (H2Bub) is positively linked to transcriptional activation, but the genetic programs affected by H2Bub to enhance drought tolerance remain largely unknown. Here, we show that OsbZIP27 interacts directly with OsHUB1/2 to regulate drought tolerance in rice by binding to the promoters of OsHAK1 and OsGLN1 to achieve H2Bub and transcriptional activation. Consistently, mutations in OsbZIP27 reduce transcription of OsHAK1 and OsGLN1, resulting in increased sensitivity to drought stress. Moreover, loss of OsHUB1 and OsHUB2 function causes hypersensitivity to drought stress, whereas OsHUB2 overexpression enhances drought tolerance. Together, our results indicate that OsbZIP27 coordinates with OsHUB1/2 to enhance rice drought tolerance by increasing H2Bub and expression of OsHAK1 and OsGLN1.

See https://pubmed.ncbi.nlm.nih.gov/39643268/

Figure 5. OsbZIP27 binds to OsHAK1 and OsGLN1 promoters to activate gene expression. A: Probes containing G-box sequences from OsHAK1 and OsGLN1 promoters, with G-boxes in red. B and C: EMSA showing binding to the G-box of OsHAK1 (B) and OsGLN1 (C) promoters. The 3′-biotin-labeled probe, unlabeled competitor probes, and GST proteins were used as controls. Red triangles indicate shifted bands. The experiment was repeated at least three times. D: Constructs containing OsbZIP27 fused with GFP driven by the 35S promoter (35S::OsbZIP27-GFP, referred to as effector), and luciferase driven by the OsHAK1 or OsGLN1 promoters (proOsHAK1::LUC or proOsGLN1::LUC, respectively; referred to as reporter). E and F: Transient trans-activation assays in tobacco leaves, showing bioluminescence signals for 35S::OsbZIP27-GFP and proOsHAK1::LUC (E) or proOsGLN1::LUC (F). 35S::GFP served as a negative control. The experiment was repeated at least three times.