Early seedling development and emergence from the soil, which are critical for plant growth and important for crop production, are controlled by internal factors, such as phytohormones, and external factors, such as light and salt. However, little is known about how light and salt signals are integrated with endogenous cues in controlling plant physiological processes. Here, we show that overexpression of rice (Oryza sativa) PHYTOCHROME-INTERACTING FACTOR-LIKE14 (OsPIL14) or loss of function of the DELLA protein SLENDER RICE1 (SLR1) promotes mesocotyl and root growth, specifically in the dark and under salt stress. Furthermore, salt induces OsPIL14 turnover but enhances SLR1 accumulation. OsPIL14 directly binds to the promoter of cell elongation-related genes and regulates their expression. SLR1 physically interacts with OsPIL14 and negatively regulates its function. Our study reveals a mechanism by which the OsPIL14-SLR1 transcriptional module integrates light and gibberellin signals to fine-tune seedling growth under salt stress, enhancing understanding about how crops adapt to saline environments.

幼苗的早期发育和从土壤中出苗对于植物生长至关重要，对作物生产也很重要，它们受到内部因素（如植物激素）和外部因素（如光和盐）的控制。然而，人们对光和盐信号如何与内源信号整合来控制植物生理过程知之甚少。在这里，我们发现水稻（Oryza sativa）植物色素相互作用因子样14（OsPIL14）的过度表达或DELLA蛋白SLENDER RICE1（SLR1）功能的丧失可促进中胚轴和根的生长，特别是在黑暗和盐胁迫下。此外，盐会诱导 OsPIL14 更新，但会增强 SLR1 的积累。OsPIL14 直接结合细胞伸长相关基因的启动子并调节其表达。SLR1 与 OsPIL14 发生物理相互作用并负向调节其功能。我们的研究揭示了 OsPIL14-SLR1 转录模块整合光和赤霉素信号以微调盐胁迫下幼苗生长的机制，增强了对作物如何适应盐分环境的理解。