外源多胺对铜胁迫下水鳖叶片多胺代谢、抗氧化系统和矿质营养元素的影响

采用营养液水培的方法,研究了外源亚精胺(Spd)和精胺(Spm)对Cu胁迫下水鳖叶片3种形态多胺(PAs)、抗氧化系统及营养元素的影响。结果表明:(1)Cu胁迫使水鳖叶片腐胺(Put)急剧积累,Spd和Spm明显下降,从而使(Spd+Spm)/Put比值也随之下降。外源Spd和Spm显著或极显著逆转Cu诱导的PAs变化,抑制Put的积累,缓解Spd和Spm的下降,从而提高了(Spd+Spm)/Put比值。(2)外源Spd和Spm抑制了Cu胁迫诱导的多胺氧化酶(PAO)的增加,缓解了二胺氧化酶(DAO)的下降。(3)与单一Cu胁迫相比,Spd和Spm显著或极显著提高了超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、游离脯氨酸(Pro)含量,从而降低了超氧阴离子(O2.-)产生速率和过氧化氢(H2O2)含量,极显著降低了丙二醛(MDA)含量,缓解了Cu诱导的氧化胁迫。(4)外源Spd和Spm显著或极显著缓解了Cu胁迫下矿质营养元素吸收平衡的紊乱。以上结果均说明了外施Spd和Spm可增加水鳖对Cu胁迫的耐受性。

Effects of exogenous polyamines on polyamines metabolism, antioxidative systems and mineral nutrition responses of Hydrocharis dubia(Bl.) Backer under Cu stress

The effects of exogenous spermidine(Spd) and spermine(Spm) on the leaves of Hydrocharis dubia under copper toxicity were investigated. The results showed that the content of putrescine (Put) increased and the contents of Spd and Spm decreased under copper stress in leaves, thereby the ratio of (Spd+Spm)/Put decreased significantly, which was concerned with the antioxidant ability in plants. Exogenous Spd or Spm markedly reversed these Cu-induced effects for partially enhanced the ratio of (Spd+Spm)/Put in leaves, which may be caused by decrease of polyamine oxidase (PAO) activity and increase of diamine oxidase (DAO) activity. It also markedly or highly significantly enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate specific peroxidase (APX) and glutathione reductase (GR), increased the contents of ascorbic acid (AsA), glutathione (GSH) and free proline (Pro), which was possibly the reason of decline of the genneration rate of superoxide anion (O?-2) and hydrogen peroxide (H2O2). So exogenous Spd and Spm restrained Cu-induced lipid peroxidation showed by decline of malondiadehyde (MDA) and soluble protein. Furthermore, exogenous Spd and Spm markedly reduced the accumulation of Cu and effectively maintained the balance of nutrient elements in Hydrocharis dubia leaves under Cu stress. These results suggested that exogenous Spd or Spm can enhance the tolerance of Hydrocharis dubia to copper by increasing the levels of endogenous Spd and Spm as well as the (Spd+Spm)/Put ratio.