Response Mechanism of Maize Inbred Lines to Cold Stress at Seedling Stage

To explore the response mechanism of maize to low temperature stress, two cold resistant inbred lines and two cold sensitive inbred lines were selected for low temperature stress treatment at 3 ℃ for 5 days, physiological and biochemical indexes detection and related gene expression analysis after stress treatment. The results showed that compared with cold resistant inbred lines, the soluble sugar content, proline content, antioxidant enzymes activities of cold sensitive inbred lines decreased significantly in the recovery growth period after low temperature treatment, which was much lower than that before treatment. The expression of ZmP5CS, the key gene of proline synthesis pathway in cold sensitive inbred lines, did not change significantly in the whole treatment process, while the expression of ZmProDH, the key gene of proline degradation pathway in cold sensitive inbred lines, reached the peak on the 5th day of low temperature treatment and decreased rapidly on the 3rd day of recovery of growth, which was significantly lower than the level before treatment. At the same time, the expression of antioxidant enzyme gene in cold sensitive inbred lines decreased significantly in the recovery period. Therefore, the accumulation of soluble sugar content, proline content and the joint participation of a variety of antioxidant enzymes were the response mechanism of the formation of chilling resistance of maize seedlings, and the recovery period was also the key period of its response mechanism.