PfnsLTPd-5 interacts with PfGELP24 to enhance drought and salt stress tolerance in Paulownia fortunei

Non-specific lipid transfer proteins (nsLTPs) are small, basic proteins widely distributed in plants and have been implicated in various stress responses. However, systematic characterization of the nsLTP gene family in Paulownia fortunei and its potential roles in drought and salt stress tolerance remain limited.

In this study, a genome-wide identification of the nsLTP gene family in P. fortunei was performed using bioinformatics approaches. A total of 78 PfnsLTP members were identified and classified into six subfamilies, which were unevenly distributed across 19 chromosomes. Promoter cis-element analysis revealed that 68 PfnsLTP members contained stress-responsive elements. Transcriptomic profiling combined with qRT-PCR validation identified eight PfnsLTPs that were significantly differentially expressed under both drought and salt stress. Protein-protein interaction and yeast two-hybrid (Y2H) analyses demonstrated that PfnsLTPd-5 interacted with PfGELP24, which was subsequently validated through bimolecular fluorescence complementation (BiFC) and Glutathione-S-transferase pull-down (GST pull-down) assays. Subcellular localization assays showed that PfnsLTPd-5 is targeted to the plasma membrane.

This comprehensive analysis provides insights into the evolution, structural features, and stress-responsive expression of the PfnsLTP gene family in P. fortunei. The candidate genes, particularly PfnsLTPd-5, are confirmed to physically interact with PfGELP24 to regulate drought and salt stress responses. lays a foundation for further functional characterization and provide new insights for future molecular breeding of stress-tolerant P. fortunei varieties.