渗透胁迫下钴和DFMA对小麦幼苗多胺含量及膜脂过氧化的影响(英文)

Effects of cobalt and DFMA on polyamine content and membrane-lipid peroxidation in wheat seedling under osmotic stresses

探讨了渗透胁迫下小麦幼苗乙烯与多胺之间是否存在底物竞争以及CoCl2和DFMA对膜脂过氧化的影响。研究结果表明,-1.0 MPa聚乙二醇(PEG)溶液对小麦幼苗根系渗透胁迫6 h时,叶片腐胺、亚精胺含量及乙烯释放量均显著提高,之后随胁迫时间延长,腐胺、亚精胺含量逐渐下降,乙烯释放量逐渐增加;当-1.0 MPa PEG溶液中加入DFMA0.5 mmol/L,在渗透胁迫过程中,相比于未加DFMA的处理,叶片腐胺和亚精胺含量均显著下降,而乙烯释放量没有显著变化;说明在-1.0 MPaPEG溶液根系渗透胁迫过程中,叶片内乙烯与亚精胺之间并不存在显著的底物竞争关系。当-1.0 MPa PEG溶液中加入CoCl22 mmol/L,乙烯释放量的增加被抑制,且腐胺、亚精胺含量显著提高;在PEG溶液中加入CoCl2还提高了叶片抗氧化酶的活力,并在胁迫至24 h时,显著降低了活性氧水平以及MDA含量,进而对细胞膜表现出保护作用。然而,在PEG溶液中加入DFMA,上述指标表现为相反的变化趋势。说明当渗透胁迫加深时,CoCl2提高多胺含量及抑制乙烯产生可以相对降低脂质过氧化程度,且能够减轻细胞膜在深度渗透胁迫下所受伤害。

The objective of this study was to elucidate whether spermidine and ethylene suffered substrate competition and how polyamines and ethylene influenced lipid peroxidation in wheat seedling leaves under the root osmotic stresses. The osmotic stresses simulated with - 1.0 MPa polyethylene glucose （PEG） solution was applied to wheat seedling roots for 6 h, 12 h, 18 h and 24 h respectively. The results showed that the putrescine and spermidine contents and the ethylene evolution in wheat seedlings were increased significantly when the osmotic stresses lasted 6 h. As the osmotic stresses prolonged, however, the putrescine and spennidine contents were declined and the ethylene evolution increased gradually. When DL - a - Difiuoromethy- larginine （DFMA） was added to the PEG solution with its concentration reaching 0.5 mmool/L, the putreseine and spermidine contents of the leaves under the stresses decreased significantly, but the ethylene evolution of the leaves was not affected markedly. The above results showed that there was probably no evident substrate competition between spermidine and ethylene when wheat seedlings were under root osmotic stress simulated with - 1.0 MPa PEG solution. The results also showed that the ethylene evolution got inhibited and the polyamlnes content got improved relatively, when CoCl2 was added to the PEG solution with its concentration at 2 mmol/L. The addition of CoCl2 also improved the activities of anti-oxidative enzymes, and reduced the reactive oxygen levels and MDA contents significantly when the stresses got aggravated, so COCl2 protected the cell membrane in some way. The above results indicatd that lipid peroxidation probably had a close relation with the variation in polyamines content, and CoCl2 could prevent the seedling membrane damage under the osmotic stresses.