Effects of cobalt and DFMA on polyamine content and membrane-lipid peroxidation in wheat seedling under osmotic stresses
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DOI:10.7606/j.issn.1000-7601.2010.01.25
Key Words: cobalt  ethylene  membrane-lipid peroxidation  osmotic stress  polyamines  wheat seedling
Author NameAffiliation
MA Lan College of Life Sciences and Technology, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
LI Chaozhou College of Life Sciences and Technology, Gansu Agricultural University, Lanzhou, Gansu 730070, China 
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Abstract:
      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 spermidine contents were declined and the ethylene evolution increased gradually. When DL-α-Difluoromethylarginine (DFMA) was added to the PEG solution with its concentration reaching 0.5 mmol/L, the putrescine 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 polyamines 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.