Ca^(2+)对苯丙烯酸胁迫下黄瓜幼苗根系活性氧代谢的影响

Effects of external Ca^(2+) on membrane lipid peroxidation of cucumber seedling roots under cinnamic acid stress

水培试验研究了外源Ca2+对苯丙烯酸(CA)胁迫下黄瓜幼苗根系的生长及活性氧代谢的影响,以探讨Ca2+缓解黄瓜CA毒害的生理机制.结果显示:CA胁迫导致黄瓜幼苗的根鲜重、主根长、一级侧根数下降,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性上升,过氧化氢酶(CAT)活性下降,超氧阴离子(O2.-)产生速率、H2O2含量、丙二醛(MDA)含量、相对电导率显著增大,表明CA胁迫使细胞发生明显的氧化损伤和膜脂过氧化;Ca2+可缓解CA胁迫对根生长的抑制,提高SOD、CAT活性,降低POD活性、O2.-产生速率、H2O2含量、MDA含量、相对电导率,表明Ca2+减轻CA胁迫对黄瓜幼苗毒性的生理机制之一,在于增强其活性氧的清除能力以及对细胞膜的稳定作用.

In order to explore the physiological mechanisms of external Ca^2＋ involved in improving cucumber （ Cucumis sativus L. ） adaptation to einnamic acid （CA） stress, the effects of Ca^2＋ on the growth and active oxygen metabolism were investigated through hydroponic experiment. The results showed that CA decreased root fresh weight, length of taproot, number of laterals and the activity of eatalase （CAT）, whereas increased the activities of superoxide dismutase （SOD）, peroxidase （POD） and superoxide anion （ O2^·- ） producing rate, contents of H2O2 and malondialdehyde （MDA） as well as electrolyte leakage, suggesting that oxidative damage and membrane peroxidation occurred in CA-treated root tissues. External Ca^2＋ promoted the activities of SOD and CAT, but reduced the activity of POD, O2^·- producing rate, the contents of H2O2 and MDA, and permeability of cell membrane under CA stress. These results indicated that the elimination of active oxygen species and maintenance of membrane stability may be one of the mechanisms of external Ca^2＋ inhancing CA tolerance of cucumber to CA stress.