Fig. 1: Discovery of bZIP49 specific splicing events in P. tomentosa.

a Cloning of bZIP49 in P. tomentosa revealed two bands: the upper band corresponds to the unspliced transcript, while the lower band represents the spliced variant. b Schematic diagram of the mRNA splicing of bZIP49 and its corresponding isoforms. The red box marks the recognition site, and the horizontal line represents the 403 bp spliced fragment. c The complete schematic diagram of the PtbZIP49 gene structure and corresponding structural diagrams of two transcription variants, PtbZIP49L and PtbZIP49S. The arrow represents the specific primer used for RT-qPCR, and the green dashed rectangle represents the excised 403 bp fragment. A red triangle indicates a premature termination codon (PTC) at the newly formed intron. d Semi-quantitation RT-qPCR product analysis of bZIP49L and bZIP49S transcript isoforms in the roots, stems, and leaves of wild-type P. tomentosa. e Immunoblot analysis of bZIP49L and bZIP49S protein isoforms. The nuclear proteins from wild-type (WT) and bzip49cr mutant lines were isolated for immunoblot assays with anti-bZIP49 antibody. *, indicates non-specific bands. f Diagrams illustrating the predicted proteins structures encoded by bZIP49L and bZIP49S. g Subcellular localization of PtbZIP49L and PtbZIP49S in N. benthamiana leaves, with RFP-HDEL used as an ER marker. h Relative expression levels of bZIP49L and bZIP49S under salt stress, with water treatments as a control. Values are means ± SE; n  =  3 technically replicates (ns P > 0.05; * P < 0.05; *** P < 0.001; one-way ANOVA). i Histochemical analysis of bZIP49_Pro-GUS/Col-0 transgenic plants treated with 200 mM NaCl for 0 or 1 h for GUS staining. j Quantitative measurement of GUS activity in bZIP49_Pro-GUS seedlings after 200 mM NaCl treatment, with untreated samples as controls. The data are shown as mean ± SE; n  =  3 biological replicates (Two-tailed Student’s t-test: *** P < 0.001). Source data are provided as a Source Data file.