H₂O₂在玉米幼苗冷胁迫及适应过程中的双重作用及与Ca～（2+）-CaM的关系

【作者】 李春光；

【导师】 龚明；

【作者基本信息】 云南师范大学 ， 环境科学， 2002， 硕士

【摘要】 本研究共分为两部分： 第一部分，以玉米幼苗（大黄和晴三）为材料，测定了两个品种1℃冷胁迫下幼苗的存活曲线和内源H₂O₂含量变化的双峰曲线。在1℃冷胁迫下，H₂O₂含量迅速上升，在4小时达到第一个峰值，后迅速下降，随着胁迫时间的延长，H₂O₂含量又连续上升，在玉米幼苗完全死亡时，又出现了第二个高峰，随后下降。后又测定了1℃冷胁迫下MDA含量的变化，根据玉米幼苗的死亡时间、MDA含量迅速上升的时间和H₂O₂含量的第二个峰值的时间进程的一致性，而证实胁迫后期的H₂O₂连续上升起到逆境伤害的作用。而用0.1mmol/L的H₂O₂预处理可提高玉米幼苗冷胁迫下的存活率，并发现外源H₂O₂处理可提高内源H₂O₂的水平，用H₂O₂含量变化的第一个峰值4小时对玉米幼苗进行1℃冷激，可明显提高玉米幼苗的耐冷性，从而说明H₂O₂在胁迫前期的迅速上升可能起到一个逆境信号的作用，而启动耐冷性的提高。从而证实H₂O₂在玉米幼苗冷胁迫及适应过程中可能具有双重作用，即在冷胁迫前期，H₂O₂的短暂上升可能起到一个逆境信号的作用，启动耐冷性的提高；而在冷胁迫后期H₂O₂的连续上升又起到逆境伤害作用。随后又测定了外源H₂O₂预处理，对内源抗氧化酶的活性的影响，发现外源H₂O₂预处理可提高内源抗氧化酶系统的活性，并且在冷胁迫过程中其活性的降低也比对照的下降的慢，从而证实H₂O₂诱导的玉米幼苗耐冷性的提高可能与抗氧化酶系统活性的增强密切相关。 由于第一部分已证实H₂O₂具有双重作用，并可作为逆境信号分子启动玉米幼苗耐冷性的提高。并且以前的研究结果已表明Ca²⁺-CaM参与了植物对胁迫的信号传导及耐性的形成。为证实Ca²⁺-CaM是否参与H₂O₂诱导的耐冷性。第二部分，以大黄幼苗为材料，测定了外源Ca²⁺预处理，下调内源Ca²⁺水平和降低内源CaM的活性（CaM的抑 Mp。在玉米幼苗冷胁迫及适应过程中的双重作用及与 caz“－co的关系制剂）对几山诱导的玉米幼苗抗冷性的效应，Cay的鳌合剂EGTA和公认的 Ca卜的胞内通道阻断剂 RR，以及 CaM的抑制剂 CPZ和 TFP都可抑制H山诱导的玉米幼苗的耐冷性，并且用低浓度的Ca‘“浸种可增加 H八诱导的玉米幼茵的耐冷性，而用高浓度的 Ca‘“浸种却降低了几山诱导的玉米幼苗的耐冷性，并发现，外源Hp。预处理，可提高内源民山含量和增强 CaM的活性，从而证实 Ca’＊CaM可能参与调控Hp。诱导的耐冷性。更多还原

【Abstract】 This study included two parts:For the first part, maize seedlings (Zea mays L. DaHuang and Qing No.3) were used as experimental material. Firstly, the survival percentage curve and the dual-peak curve of H2O2 content of two kind of maize seedlings were investigated under chilling stress. Under chilling stress, H2O2 content increased sharply, and showed the first peak at the 4 hour, then decreased sharply. And it also increased following prolong of the time of chilling stress, and showed the second peak at the time of all maize seedlings dead, then decreased. Secondly, the change of MDA content of maize seedlings was measured under chilling stress. According to the inconsistent of time of dead and the second peak of H2O2 and MDA content increase sharply of maize seedlings, we suggested that the increase of H2O2 content had hurt role for maize seedlings at the later stage of chilling stress. The cold-tolerance and the H2O2 content of maize seedlings increased by the H2O2 pre-treated. And we found that the survival percentage of maize seedlings increase by 4 hour cold-shock. So we suggested that the increase quickly of H2O2 content at earlier stage of chilling stress was a stress signal, and induced the increase of cold-tolerance of maize seedlings, the effect of H2O2 pre-treated on the activity of antioxidant enzyme was also measured. It showed that the activity of antioxidant enzyme went up by H2O2 pre-treated, and decrease was slower than the control seedlings. So we suggested that the increase of cold-tolerance of H2O2 induced was often related to the enhance of activity of antioxidant enzyme system in plant.In the first part, we had suggested that H2O2 has dual role, and could induce the increase of cold-tolerance. And in the former results, it indicated that Ca2+-CaM had involved in the signal transduction for cold stress and the formation for cold tolerant of plants. So we might conclude calcium messenger system might involve in the increase of cold-tolerance H2O2-induced. So the effect of modified of Ca2+ and CaM level on the cold-resistance of H2O2 induced of maize seedlings was measured . We found that EGTA, a Ca2+ chelator, andRR, the putative mitochondrial Ca2+ channel blocker, and CaM inhibitor CPZ and TFP all could inhibit the increase of cold-tolerance of H2O2 induced. Our result also showed that the pre-treatment of lower concentration Ca2+ could increase the cold-tolerance of H2O2 induced, but the higher concentration Ca2+ had reverse result. It showed that H2O2 pre-treated could increase H2O2 content and CaM activity .So we demonstrated that Ca2+-CaM might regulate the cold-tolerance of H2O2 induced.更多还原