Effects of exogenous NO on antioxidant system of Taxus plants under simulated acid rain stress

Taxus is a famous medicinal and landscape tree species. The aim of this study was to explore the effect of exogenous nitric oxide (NO) on the resistance of Taxus plants to acid rain stress and to identify Taxus species with strong acid rain resistance by principal component analysis and comprehensive evaluation. In this study, sodium nitroprusside (SNP) was used as the exogenous NO donor. The effects of different SNP solution concentrations on the antioxidant systems of three Taxus species subjected to simulated acid rain stress (pH = 3.0) were compared. In order to achieve this goal, we determined the rate of O2- production, the ASA and GSH contents in leaves of three Taxus plants (Taxus mairei, Taxus chinensis, and Taxus yunnanensis). At the same time, the active leaves of some antioxidant enzymes (SOD, POD, CAT, APX and GR) were determined. For Taxus chinensis plants subjected to acid rain stress, treatment with an SNP concentration of 0.25 mmol·L-1 led to the most significant improvements in the antioxidant system. For Taxus mairei and Taxus yunnanensis, the treatment with the SNP concentration of 0.50 mmol·L-1 was best for improving their antioxidant systems under stress. Meanwhile, Taxus chinensis had the strongest resistance to simulated acid rain, followed by Taxus mairei and Taxus yunnanensis.