Response difference of antioxidant and ascorbate-glutathione cycle system to NaCl stress between salt tolerant and sensitive barley cultivars at the seedling stage

ObjectivesThe aim of this study was to compare the response differences of antioxidant and ascorbate-glutathione cycle system to NaCl stress between the salt tolerant and sensitive barley cultivars at the seedling stage.

MethodsA hydroponic experiment was conducted using salt-tolerant cultivar (12pj-118) and non-tolerant cultivar (12pj-045) of barley as materials. Six NaCl stress concentrations were set up, including 0, 100, 200, 300, 400 and 500 mmol/L. The plant samples were collected when the forth leaf emerged. The active oxygen metabolism, antioxidant enzyme activity and ascorbate glutathione cycle were determined.

ResultsThe results showed that the \rmO_\small 2^\overline \,\cdot\, production rate, H₂O₂ content and MDA content were increased gradually with the increase of NaCl levels, and the increased rates of the 12pj-118 were lower than those of the 12pj-045. The activities of SOD, POD, CAT, GR and APX, the contents of AsA and GSH and the ratios of AsA/DHA were increased at first and then decreased. The increased rates of the SOD, POD and CAT activities were much higher in the 12pj-118 under different NaCl concentrations at first, and reduced rates were lower later. The increased rates of APX and GR activities of 12pj-118 were higher than those of 12pj-045 under the same salt concentration, and the reduced rates were lower. Under different NaCl concentrations, the increased rates of the AsA contents and AsA/DHA ratios of 12pj-118 were higher than those of 12pj-045. The ratios of GSH/GSSG showed a wavy change in two barley cultivars, and the 12pj-118 was able to maintain high GSH contents and GSH/GSSG ratios under higher NaCl concentrations. These results indicated that the salt resistance of 12pj-118 was better than the 12pj-045.

ConclusionsThe response of NaCl stress was different on antioxidant system and ascorbate-glutathione cycle at the seedling stage. At a given range, with the increase of NaCl concentration, the increased rates of the SOD, POD, CAT, APX, GR, AsA and GSH of the12pj-118 were much higher than those of the 12pj-045 under different NaCl concentrations, and reduced rates were lower. The results indicated that antioxidant activity and ascorbate glutathione cycle were closely related to salt tolerance of barley seedlings.