The Effects of Chilling on Antioxidant Enzyme System and Related Gene Expression Levels in Sweet Corn Seeds with Different Germination Characteristics

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Sweet corn is a vegetable and grain dual-use crop with high economic value and industrial advantages. Low temperature stress significantly reduces the germination rate of sweet corn seeds, which has a negative impact on both quality and yield. This study used the chilling sensitive sweet corn inbred line 20hi111 and the chilling tolerant sweet corn inbred line T135 as experimental materials to measure the MDA (malondialdehyde) and H<sub>2</sub>O<sub>2 </sub>content, CAT, POD, and SOD enzyme activities, and enzyme gene expression patterns during seed germination under low temperature (10°C) and normal temperature (25°C) treatments. The research results indicated that during low-temperature germination, the H<sub>2</sub>O<sub>2</sub> content and CAT activity of 20hi111 were generally higher than those of T135, while the POD and SOD activities and MDA content were generally lower than those of T135. There was no strict consistency between gene expression and enzyme activity. At low temperature, the expression of <i>ZmCAT1</i> and <i>ZmCAT3</i> in 20hi111 was significantly higher than T135, while there was no significant difference in <i>ZmPOD1</i>. In 20hi111, <i>ZmPOD3</i> was first lower and then higher than T135, and <i>ZmSOD3</i> and <i>ZmSOD9</i> were lower than T135 under low temperature treatment. In this study, the activity of antioxidant enzymes and the expression of antioxidant enzyme-related genes in sweet corn inbred lines with different germination characteristics under low temperature were analyzed, which provided some theoretical basis for cultivating sweet corn varieties with low temperature tolerance.