Chilling stress is a major abiotic constraint that affects sweet corn seedling establishment. Spermidine (Spd) is known to participate in the cold stress response in plants, nonetheless, the molecular mechanisms are largely unknown. The present study reported that exogenous Spd not only stimulated seedling growth but also enhanced photosynthetic attributes under chilling stress. Further analysis revealed that Spd application resulted in depressed abscisic acid (ABA) content and affected the expression of ABA-responsive genes. The augmented antioxidant enzymes activities, coupled with declined reactive oxygen species (ROS) content, were observed in response to Spd treatment under chilling stress. Moreover, Spd up-regulated the transcription levels of some Ca²⁺ transport-related genes. We propose that Spd contributes to cold tolerance in sweet corn seedlings via the regulation of genes involved in the ROS, ABA pathways and Ca²⁺ transport.

低温胁迫是影响甜玉米幼苗生长的主要非生物限制因素。已知亚精胺（Spd）参与植物的冷胁迫响应，但是其分子机理尚不清楚。本研究报告说，外源Spd不仅刺激幼苗生长，而且增强了寒冷胁迫下的光合特性。进一步的分析表明，Spd的施用导致脱落酸（ABA）含量降低，并影响ABA反应基因的表达。在寒冷胁迫下，响应Spd处理后，观察到抗氧化酶活性增强，活性氧（ROS）含量下降。此外，Spd上调了某些Ca ²⁺的转录水平转运相关基因。我们建议Spd通过调节参与ROS，ABA途径和Ca ²⁺转运的基因来促进甜玉米幼苗的耐冷性。