Effects of exogenous NO treatment on aluminum stress resistance of four Eucalyptus seedlings

Abstract

To investigate the effect of exogenous nitric oxide (NO) on aluminum tolerance of Eucalyptus seedlings under aluminum stress. In this study, sodium nitroproside (SNP) was used as exogenous NO donor in four kinds of Eucalyptus seedlings (Eucalyptus grandis, E. urophylla, E. tereticornis, E. urophylla×E. grandis). The effects of different concentrations of NO (0, 50, 100, 200, 400, 800 μmol·L-1) on the physiological indices of ROS, antioxidant enzyme activities and the contents of organic osmotic regulatory substances of Eucalyptus seedlings under 120 mg·L-1 aluminum stress were studied, and the differences of aluminum tolerance of four Eucalyptus species under NO treatment were compared. The results were as follows: (1) The addition of exogenous NO (50 μmol·L-1≤NO≤200 μmol·L-1) under aluminum stress promoted the contents of soluble sugar and soluble protein, the activities of antioxidant enzymes (SOD, POD, CAT, APX), the removal of ROS in the body, the reduction of MDA accumulation, and the improvement of aluminum stress resistance. However, under high concentration of NO(≥800 μmol·L-1), the activities of antioxidant enzymes and the contents of osmotic regulatory substances decreased in Eucalyptus seedlings, showing stress response. (2) NO significantly improved the aluminum tolerance of sensitive Eucalyptus, but not significantly improved the aluminum tolerance of tolerant Eucalyptus. Finally, the aluminum resistance of four Eucalyptus species tended to be consistent under the action of NO. (3) SOD, MDA, CAT, O2-, soluble protein and soluble sugar could be used as key indicators to evaluate the aluminum tolerance of Eucalyptus. This study provides a scientific reference for the selection of aluminum tolerance germplasm resources of Eucalyptus, and laid a foundation for further understanding of the mechanism of NO regulating the difference of aluminum tolerance between Eucalyptus species.

Keywords

• eucalyptus
• exogenous no
• aluminium stress
• physiological indexes
• principal component analysis
• aluminum tolerance