Separate and combined effects of excess copper and Fusarium culmorum infection on growth and antioxidative enzymes in wheat (Triticum aestivum L.) plants

Abstract

The effect of stress combinations on plants cannot be extrapolated from the response to each of the applied stressors. Greenhouse experiments were carried out on soil to which copper ions were introduced at four concentrations (0, 150, 400, and 600 mg kg⁻¹). Copper treatments without or with Fusarium infection were established. Both stress factors, applied separately or together inhibited growth with the exception of the lowest Cu concentration, which stimulated growth of healthy plants. Depending on concentration, Cu did not change or increased the activity of root peroxidase and leaf catalase, and decreased ascorbate peroxidase (APO) activity in leaves and roots. Infection increased the activities of the enzymes with exception of root APO. The simultaneous presence of these two stress factors modified their individual effects. Generally, the stress combination aggravated the plant status though an opposite trend was observed in some cases.

Keywords:

• ascorbate peroxidase
• catalase
• combined stress
• copper
• Fusarium culmorum
• peroxidase

Acknowledgments

The authors thank the phytopathologist Mrs Elena Boncheva for her scientific assistance with Fusarium infection, Mrs Ana Trifonova for excellent technical support, Prof. Aglika Edreva for reviewing the manuscript and giving valuable suggestions and anonymous reviewer for scrutinizing the text in order to improve its readability.