Translationally controlled tumor protein GmTCTP2 positively regulates plant drought tolerance through GmSCEc mediated SUMOylation

The translationally controlled tumor protein (TCTP) represents a multifunctional and evolutionarily conserved protein family in eukaryotes. Despite its biological significance, the genetic characteristics and stress-responsive mechanisms of TCTP remain uncharacterized in soybean. This study identifies GmTCTP2 as a drought-responsive gene showing transcriptional upregulation under PEG-induced dehydration and multiple abiotic stresses. Through comprehensive interaction assays including GST pull-down, co-immunoprecipitation (Co-IP), and bimolecular fluorescence complementation (BiFC), we demonstrate that GmTCTP2 physically interacts with the SUMO E2 conjugate enzyme GmSCEc. This interaction enables GmTCTP2 SUMOylation at lysine residues 101 and 167, significantly enhancing its protein stability under drought conditions. Phenotypic analysis revealed that the Arabidopsis TCTP mutant Attctp displays drought-sensitive characteristics, which could be fully complemented by wild-type GmTCTP2 but not by its SUMOylation-deficient variant GmTCTP2 K101 , 167R . Transgenic Arabidopsis overexpressing GmTCTP2 exhibited substantially improved drought tolerance through enhanced photosynthetic efficiency, ROS scavenging capacity, and hormonal signaling modulation, as evidenced by physiological assessments and transcriptomic profiling. Our findings establish that GmSCEc-mediated SUMOylation of GmTCTP2 critically contributes to drought stress adaptation, providing both mechanistic insights into TCTP regulation and valuable genetic resources for engineering drought-resistant crops.