Screening for GmRCD1-Interacting Proteins in Glycine Max and Characterization of the GmRCD1-GmNAC058 Interaction

In response to abiotic stress, plants utilize hub protein-mediated signaling networks, with members of the SIMILAR TO RCD ONE (SRO) protein family playing a pivotal role in regulating stress resistance pathways. This study investigates the functional role of the soybean GmRCD1 protein and its interaction mechanisms to elucidate its molecular regulatory network in stress resistance responses. By employing yeast two-hybrid technology to screen a soybean cDNA library under high-salt stress conditions, 17 potential interacting proteins were identified, which include NAC transcription factors (e.g., GmNAC058), ubiquitin-proteasome proteins, and ribosomal proteins. Subsequent validation using GST pull-down and bimolecular fluorescence complementation assays confirmed the direct interaction between GmRCD1 and GmNAC058, which is mediated by the RST domain of GmRCD1 and the C-terminal disordered region (amino acids 288-323) of GmNAC058. Subcellular localization studies revealed that both proteins are nuclear-localized, aligning with their roles in transcriptional regulation. Furthermore, PAR binding assays demonstrated that both GmRCD1 and AtRCD1 can bind to PAR polymers; however, PARP activity analysis revealed that neither protein exhibits catalytic activity, indicating their participation in stress responses via non-enzymatic mechanisms. This study represents the first to elucidate the interaction network and structural basis between soybean GmRCD1 and GmNAC058, providing crucial theoretical support for understanding the multifunctional roles of plant hub proteins in stress resistance regulation and for molecular breeding in soybean.