Overexpressing the Sedum alfredii Cu/Zn Superoxide Dismutase Increased Resistance to Oxidative Stress in Transgenic Arabidopsis

Abstract

Superoxide dismutase (SOD) is a very important reactive oxygen species (ROS)-scavenging enzyme. In this study, the functions of a <i>Cu/Zn SOD</i> gene (<i>SaCu/Zn SOD</i>), from <i>Sedum alfredii</i>, a cadmium (Cd)/zinc/lead co-hyperaccumulator of the Crassulaceae, was characterized. The expression of <i>SaCu/Zn SOD</i> was induced by Cd stress. Compared with wild-type (WT) plants, overexpression of <i>SaCu/Zn SOD</i> gene in transgenic <i>Arabidopsis</i> plants enhanced the antioxidative defense capacity, including SOD and peroxidase activities. Additionally, it reduced the damage associated with the overproduction of hydrogen peroxide (H₂O₂) and superoxide radicals (O₂^•-). The influence of Cd stress on ion flux across the root surface showed that overexpressing <i>SaCu/Zn SOD</i> in transgenic <i>Arabidopsis</i> plants has greater Cd uptake capacity existed in roots. A co-expression network based on microarray data showed possible oxidative regulation in <i>Arabidopsis</i> after Cd-induced oxidative stress, suggesting that S<i>aCu/Zn SOD</i> may participate in this network and enhance ROS-scavenging capability under Cd stress. Taken together, these results suggest that overexpressing <i>SaCu/Zn SOD</i> increased oxidative stress resistance in transgenic <i>Arabidopsis</i> and provide useful information for understanding the role of <i>SaCu/Zn SOD</i> in response to abiotic stress.