Responses of Phragmites australis to copper stress: A combined analysis of plant morphology, physiology and proteomics

Few relevant research attempts have been made to determine heavy metal resistance mechanisms of rhizomatous perennial plants. Thus, it is pertinent to investigate the physiological and biochemical changes in Phragmites australis under metal-stressed conditions to facilitate the development of strategies to enhance copper tolerance. We measured parameters related to plant growth and development, metal translocation, and physiological responses of P.australis under the effects of copper stress. Additionally, the differentially expressed proteins (DEPs) were evaluated by the isobaric tag for relative and absolute quantification (iTRAQ) system. Here, we found that physiological parameters such as chlorophyll, ascorbic acid and proline were more sensitive to copper stress compared to growth parameters. In addition, P.australis also fixed a large amount of copper to its roots, limiting the migration of copper to other parts of the plant. The analysis results further showed that copper stress can affect photosynthesis by inhibiting the activity of PSI, PSII, and LHCII. Additionally, P. australis respond to copper stress with changes in the pool size of ascorbic acid and proline to increase copper tolerance and protect photosynthesis, while the former is synthesized through D-Mannose/L-Galactose pathway and the latter is synthesized through ornithine pathway. These results provide a theoretical basis for understanding the tolerance and repair mechanisms of plants.

Keywords: Phragmites australis; Ascorbic acid; Photosynthesis; Phytoremediation; Proline; Proteomic.