The Cysteine-Rich Peptide PeGASA15 from Populus euphratica enhances drought and salinity tolerance in poplar

Poplar is a key industrial timber species, valued for its fast growth and diverse applications in pulp, plywood, furniture, and premium industries. Drought and salinity are key environmental factors that limit its growth and geographic distribution. Therefore, studying the molecular mechanisms of drought and salt tolerance in poplar and developing stress-resilient germplasm is crucial for boosting forest productivity and tackling climate change. Cysteine-rich peptides (CRPs) play a pivotal role in mediating abiotic stress responses in plants; however, the molecular mechanisms underlying their function in Populus remain inadequately characterized. In this study, we identified the CRP gene PeGASA15 from P. euphratica. Subcellular localization analysis showed that PeGASA15 is localized to the cell membrane. Moreover, drought and salt treatments significantly induced the expression of PeGASA15. Further investigation revealed that overexpression of PeGASA15 in Arabidopsis thaliana resulted in higher germination rates and longer root lengths under mannitol and ABA treatments compared to wild-type (WT) plants. The overexpression of PeGASA15 also upregulated the expression of ABA signaling pathway and abiotic stress-related genes in transgenic triploid white poplars (P. tomentosa ‘YiXianCiZhu B38’), enhancing ROS scavenging ability under stress conditions and improving tolerance to drought and salinity. Additionally, yeast two-hybrid (Y2H) and split luciferase complementation assays (SLCAs) confirmed an interaction between PeGASA15 and TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE 3 (PeTTL3) in P. euphratica, suggesting that PeGASA15 may regulate drought and salt tolerance in poplar through its interaction with PeTTL3. In conclusion, our findings demonstrate that PeGASA15 plays a significant role in the response of poplar to drought and salinity, providing an important candidate gene for molecular breeding of abiotic stress resistance in forest trees.