Effects of Ozone Stress on Root Morphology and Reactive Oxygen Species Metabolism in Soybean Roots

Abstract

In recent years,the elevated ozone has become a serious problem which has some significant effects on plant.The response of morphological characteristics and reactive oxygen species metabolism in roots of soybean to elevated ozone concentrations was investigated in this paper.Soybean grown in open top chambers(OTCs)exposed to ambient air(O3=40 nL·L-1)and elevated ozone(O3=110±10 nL·L-1).Root volume,nodule number,root and nodule dry weight,relative electrical conductivity and malonaldehyde(MDA),hydrogen peroxide(H2O2)and superoxide anion(O-·2)production rate,activities of superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)were determined.The results showed that the root volume and root dry weight per plant decreased,then the nodule number and nodule dry weight per plant also declined with ozone concentration rising.Compared to CK,elevated ozone treatment significantly increased MDA and H2O2 content(P0.05),relative electrical conductivity and O-·2 production rate(P0.05).SOD activity was higher than CK at branching stage but lower than CK at the other stages under elevated ozone stress.Activity of CAT was lower than CK at flowering stage but higher at the other stages.Activity of POD increased in the early period and decreased in the late period,which was higher than CK at all growing stages.It can be concluded that the ozone stress has negative effects on soybean roots on account of oxidative damage,which restrains the growth and development of soybean roots.