Genome-Wide Characterization and Expression Analysis of the nsLTP Gene Family in Potato (Solanum tuberosum) in Response to Drought Stress

Potato (Solanum tuberosum L.) is the fourth largest food crop in the world, and drought stress seriously affects its yield and quality. Plant non-specific lipid transfer proteins (nsLTPs) play an important role in resisting biotic and abiotic stresses. Although the functions of nsLTPs have been reported in crops such as rice (Oryza sativa L.) and Arabidopsis thaliana, the systematic identification and functional analysis of nsLTPs in potato, a key food crop sensitive to drought, remain very scarce. In this study, the whole genome identification, drought stress expression analysis and potential function prediction of the potato StnsLTP gene family were carried out by bioinformatics and real-time quantitative polymerase chain reaction (RT-qPCR). A total of 123 potato StnsLTP genes were identified, which were unevenly distributed on 11 chromosomes. The encoded amino acid length was 88–390 aa, and 91.1% of StnsLTP proteins were hydrophobic. Conserved motif analysis showed that motif 4 was the most important conserved motif in this family. There were 0–4 introns and 1–4 exons. The family identified 45 pairs of tandem duplicated genes and 20 pairs of segmentally duplicated genes, and the nsLTP potato genes showed close phylogenetic relationships with tomato nsLTP genes. Combined with transcriptome data, three PEG-responsive candidate genes, StnsLTP.115, StnsLTP.117, and StnsLTP.118, were screened. After polyethylene glycol 6000 (PEG 6000) simulated drought treatment, the three genes showed different degrees of induced expression in the roots, stems and leaves of the three potato cultivars, and their expression differed markedly across cultivars, tissues and sampling time points. This study systematically elucidated the structure and evolutionary characteristics of the potato StnsLTP family, and identified three candidate genes responsive to PEG-simulated drought stress. This not only provides a basic reference for the functional study of the potato StnsLTP family, but also offers clues for analyzing potato drought response pathways and exploring candidate genes for potato stress response research.