Influence of different water stress to glutathione antioxidant defense system in Robinia pseudoacacia.

Three degrees of soil moisture treatments were adopted by the maximum soil capacity for holding water being 70%,55% and 40%,to simulate the environment conditions with no water stress,mild water stress,and severe water stress,respectively.In order to explore the antioxidation of glutathione antioxidant defense system of Robinia pseudoacacia,we investigated the adaptive variation of reduced glutathione (GSH) and ascorbic acid (AsA) contents,enzymes activities of glutathione reductase (GR),superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in leaves and roots of R.pseudoacacia under artificial water controlling circumstances.The results demonstrated that the GSH and AsA contents as well as GR and SOD activites in roots was lower than in leaves of R.pseudoacacia whether under normal water condition or in water stress conditions.GSH-Px activity is higher in roots than in leaves only in severe water stress condition.The GSH contents of R.pseudoacacia first increased and then decreased in leaves,but gradually increased in roots.AsA content in leaves decreased whereas it first increased then decreased in roots with the increase of water stress.The activities of GR either in leaves or roots decreased according to the increasing of water stress.The activity of GR in leaves was much higher than that in roots no matter under what soil water conditions.The activities of GSH-Px and SOD in leaves increased under the mild water stress and decreased under the severe water stress,while GSH-Px and SOD activities in roots enhanced with the increase of water stress.The result revealed that GSH and GSH-Px of glutathione antioxidant defense system for R.pseudoacacia played an important role in getting rid of reactive oxygen species which caused by water soil stress.Therefore,improving GSH content and GSH-Px activity are the main means for R.pseudoacacia in responding water soil stress.