Copper toxicity in Prunuscerasifera: growth and antioxidant enzymes responses of in vitro grown plants

Rootstocks of fruit trees, commonly used to regulate growth, precocity, fertility, and yield, can also be used to solve problems associated with soils pollution such as copper excess. Despite their potential use for phytoremediation, information on the physiological, biochemical, and molecular aspects of heavy metal toxicity stress on fruit tree rootstocks remains limited. In this study of Prunus cerasifera, a peach rootstock, growth responses, CAT and SOD activity levels, and the modulation of transcription of catalase and superoxide dismutase genes were analyzed after exposure to various copper concentrations. P. cerasifera plantlets tolerated copper concentrations up to 50 μM and unexpectedly showed improved iron uptake under low to moderate concentrations (from 0.1 to 50 μM). At 100 μM of copper, plantlets reduced relative growth rate for both fresh and dry weight and developed severe browning which progressed to necrosis. Stress due to copper toxicity resulted in an increase in total catalase and superoxide dismutase activity and a simultaneous induction of Sod and Cat gene expression. This study demonstrated that P. cerasifera is quite tolerant to copper and mobilizes catalase and superoxide dismutase in order to mitigate copper-stress damages.