Genome-Wide Characterization of the ScLOR Gene Family in Wild Tomato Solanum lycopersicoides Reveals ScLOR16 as a Negative Regulator of Cold-and Drought-Stress Tolerance
The LOR (LURP-one related) gene family encodes proteins containing conserved LOR domains; however, its functions in plant abiotic stress responses remain largely unexplored. In this study, we systematically identified and characterized the LOR gene family in the stress-tolerant wild tomato Solanum lycopersicoides using comprehensive bioinformatic analyses and conducted functional validation of the candidate gene ScLOR16. A total of 19 ScLOR members were identified and classified into eight phylogenetic subgroups. Numerous cis-acting elements associated with responses to abscisic acid (ABA), cold, and drought, including ABRE, LTR, and MBS, were detected in the promoter regions, suggesting that the ScLOR family may be broadly involved in ABA-mediated stress signaling pathways. RT-qPCR analysis revealed that ScLOR16 expression was significantly induced by both cold and drought treatments. Subcellular localization assays demonstrated that ScLOR16 is localized in both the nucleus and cytoplasm. Virus-induced gene silencing (VIGS) was subsequently employed to generate ScLOR16-silenced plants. Following 24 h of cold treatment at 4 °C and four days of drought stress, ScLOR16-silenced seedlings exhibited significantly less severe wilting symptoms than empty-vector controls. Physiological analyses showed that silenced plants exhibited enhanced superoxide dismutase (SOD) and peroxidase (POD) activities, increased proline accumulation, and decreased thiobarbituric acid-reactive substances (TBARS) content. Collectively, these results indicate that reduced ScLOR16 transcript levels are associated with enhanced cold and drought tolerance, accompanied by alterations in antioxidant defense and osmoprotection-related physiological markers. This study yields new insights into the evolution and stress-related functions of the ScLOR family.