本研究以云南高海拔耐低温籼稻品种滇屯502及其近等位基因系但对低温敏感的滇屯506为研究对象，旨在探究低温胁迫条件下这2个水稻品种在生理代谢活动及低温响应基因表达方面的差异，从而为揭示滇屯502耐低温的分子机制提供理论依据。实验在相同环境下对两种水稻幼苗实施了低温处理，并系统分析了低温胁迫下水稻苗期叶片的多项生理指标变化，包括水分、叶绿素、脯氨酸（Pro）、丙二醛（MDA）、可溶性糖含量以及抗氧化酶系统的活性等。同时，本研究还检测了与水稻低温抗性相关的关键基因，如COLD1、OsRAN1、OsCAF1B、OsFAD8、OsAOX1a和OsPHY1的表达量变化。结果显示，滇屯502主要通过提高Pro含量、增强抗氧化酶活性以及上调OsCAF1B、OsFAD8、OsAOX1a和OsPHY1等基因表达水平来应对低温胁迫，从而保护苗期水稻免受低温伤害。

This study selected the low-temperature-tolerant indica rice variety Diantun 502 and its near- allele low-temperatures sensitive line Diantun 506 as the research subjects, aiming to explore the differences in physiological metabolic activities and low-temperature response gene expression between these two rice varieties under low-temperature stress, thereby providing a theoretical basis for revealing the molecular mechanism of Diantun 502's low-temperature tolerance. The experiment subjected the seedlings of both rice varieties to low-temperature treatment under the same environmental conditions and systematically analyzed the changes in various physiological indicators in the leaves of rice seedlings under low-temperature stress, including water content, chlorophyll content, proline content, malondialdehyde content, soluble sugar content, and the activity of the antioxidant enzyme system. Additionally, this study also detected the changes in the expression levels of key genes related to rice low-temperature resistance, such as COLD1, OsRAN1, OsCAF1B, OsFAD8, OsAOX1a and OsPHY1. The results showed that Diantun 502 mainly respond to low temperature stress by increasing the content of proline, enhancing the activity of antioxidant enzymes, and upregulating the expression levels of genes such as OsCAF1B, OsFAD8, OsAOX1a, and OsPHY1, thereby protecting the rice seedlings from low-temperature damage.