The Alleviative Effects of Salicylic Acid on the Activities of Catalase and Superoxide Dismutase in Malting Barley (Hordeum uhulgare L.) Seedling Leaves Stressed by Heavy Metals

Abstract

AbstractAs toxic divalent heavy metal ions, Zn2+, Cu2+, Mn2+, Cd2+, Hg2+, and Pb2+ exert certain negative effects on plant growth and development, which has been paid huge amount of attention to in the management of heavy metal pollution. As a novel kind of endogenous plant hormone, salicylic acid (SA) is considered to exert beneficial physiological effects on plants. In this paper, the activities of catalase (CAT) and superoxide dismutase (SOD) in seedling leaves of a malting barley variety (called Ganpi No.4) cultured under hydroponic cultivation was measured under different treatments of Zn2+, Cu2+, Mn2+, Cd2+, Hg2+, and Pb2+ and under different treatments of SA alleviation, respectively, and such values were then compared and analyzed. The results showed that all treatments of different ions and the activities of CAT and SOD and all SA‐alleviated treatments and the activities of CAT and SOD exhibited nonlinear relationships. Zn2+, Cu2+, Mn2+ exerted less severe stresses on the activities of CAT and SOD at lower concentrations, and led to significantly inhibitive effects on the activities of CAT and SOD at higher concentrations. And Cd2+, Hg2+, and Pb2+ exerted significantly repressing effects on the activities of CAT and SOD. As for SA's alleviative effects, such effects were salient for most concentrations of Mn2+, Zn2+, and Cu2+ treatments and lower concentrations of Cd2+, Hg2+, and Pb2+ treatments, while were not significant for higher concentrations of Cd2+, Hg2+, and Pb2+ treatments. These data provided theoretical references for studies on physiological mechanism of cereal crops' resistance or tolerance to heavy metal stress as biomarkers.