外源水杨酸和内源H_2O_2对黄瓜抗冷性的影响

Effect of exogenous salicylic acid and endogenous H_2O_2 on physiological parameters in cold stored cucumber

以“赖多星”荷兰小黄瓜为试材,研究了外源水杨酸(SA)处理和处理前用二甲基硫脲(DMTU)抑制内源H2O2处理对2℃冷藏条件下黄瓜果皮细胞膜系统的伤害以及对活性氧代谢的影响。SA处理诱导了冷藏初期果实中H2O2含量的升高,延缓了丙二醛(MDA)和膜渗透率的增加,提高了低温下果实过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)的活性,超氧化物歧化酶(SOD)活性冷藏后期有所增加,在冷藏结束时CAT、APX和SOD活性分别比对照提高57.1%、92.3%和23.1%。过氧化物酶(POD)活性冷藏前后没有明显变化,推测SOD、POD不是抗冷系统中的关键因子。抑制内源H2O2后进行水杨酸处理,MDA含量和细胞膜渗透率增加,抑制了CAT、APX的活性。结果显示,SA处理可以有效提高黄瓜的耐冷性,减少低温对细胞膜系统的伤害,提高抗氧化酶的活性。抑制内源H2O2后显著抑制了由SA诱导的黄瓜耐冷性的提高,说明冷藏初期内源H2O2在SA诱导的果实抗冷性中发挥重要作用。

The effect on the injury of cell membrane and metabolism of dynamic changes of reactive oxygen in a coldstored cucumber at 2 13 by salicylic acid （SA） treatment and pretreatment with dimethylthiourea （a trap for H2O2） before SA treatment was studied. A SA treatment enhanced the endogenous H2O2 content in the beginning of storage, postponed the increases of MDA and relative ratio of electrolyte and increased the activities of CAT and APX. The activity of SOD was increased in the end of storage and the activity of POD had no obvious changes before and after the storage. Compared with the controls, at the end of storage the activities of CAT, APX and SOD of SA treatment increased by 57. 1 %, 92.3 % and 23. 1%, respectively, which hinted that they are not the key enzymes in antioxidant enzyme system. The relative ratio of electrolyte and MDA content were remarkably increased by pretreatmect with dimethylthiourea before SA treatment and furthermore, the activities of CAT and APX were inhibited, which might aggravate chilling damage. These results indicated that exogenous SA treatment increased cold tolerance of cucumber; pretreatment with dimethylthiourea （a trap for H2O2） remarkably inhibited cold tolerance induced by salicylic acid and endogenous H2O2 might be required for SA-enhanced cold tolerance.