Gallic acid (GA) alleviating copper (Cu) toxicity in maize (Zea mays L.) seedlings

The aim of this study is to determine the effect of GA on maize seedlings as well as its antioxidative effect under copper (Cu) stress. To that end, maize seedlings were exposed to 1.5 mM GA and 1 mM Cu solutions, and the seedlings were allocated to following experimental groups: 18-hr distilled water (DI) (Control), 6-hr GA + 12-hr DI (GA), 6-hr DI + 12-hr Cu (Cu), 6-hr GA + 12-hr Cu (GA + Cu), 12-hr Cu +6-hr GA (Cu + GA), and 18-hr GA and Cu mixture (GA = Cu). The experiment was designed by randomized block design with three repetitions. The results showed that GA alone and GA + Cu treatments significantly decreased membrane damage and H2O2 formation compared to the other treatments. GA formation was determined to be highest in turn in treatments GA + Cu and GA alone. The proline content significantly decreased in treatments GA alone and GA + Cu. The highest catalase (CAT) activity was observed in GA alone application, whereas GA + Cu treatment led to increase in guaiacol peroxidase (GPX), superoxide dismutase (SOD), and ascorbate peroxidase (APX) activities. GA has a protective effect on chlorophyll contents and relative water content (RWC), but not on carotenoid levels under Cu stress. Overall, GA alone application or GA + Cu stress may prevent the formation of reactive oxygen species (ROS) due to chelation effect of GA. © 2019, © 2019 Taylor & Francis Group, LLC

Copper Stress and Responses in Plants

Copper is a micronutrient necessary for normal plant growth and development; however, its deficiency and redundancy result in some defects in plant metabolism, especially photosynthesis. Plants are evolved to counterattack the adverse effects of copper by developing protective mechanisms, one of which is exclusion of copper ions from the cells by sequestration, which is a kind of isolation Cu from cellular components. The other way is reduction of ion uptake by roots. When the roots are exposed to excess copper, then detoxification strategies such as metal chelation and transport and activation of signal mechanisms, hormones, proteins, and antioxidant system are induced. This chapter gives an overview of the effect of copper stress on plant growth, photosynthesis, and the antioxidant system. We present insight into genetic and molecular aspects of signal transduction in response to copper stress. © 2016 Elsevier Inc. All rights reserved