Copper resistance mechanisms in plant pathogenic bacteria

Abstract

Copper is an essential element for microbes as it is involved in many redox reactions. Numerous resistance systems have been evolved in microbes to maintain copper homeostasis under copper stress conditions. These systems are responsible for the influx and efflux of copper ions in the cells. In phytopathogenic bacteria, copper ions play essential roles during disease development in plants. Copper-based chemicals are extensively used for control of diseases caused by bacteria, which leads to induced pathogen resistance derived from various copper resistance systems. Previous studies have shown that copper ions are harnessed by host plants to protect against bacterial infections, triggering immune responses through activation of defence signalling pathways. Thus, it was anticipated that bacterial copper resistance could play an alternative role in adaptation to plant immunity. This review summarizes current knowledge of copper resistance systems in plant pathogenic bacteria, which may provide a new perspective of molecular mechanisms associated with bacterial adaptation in host plants.