Resistances and Physiological Responses of Impatiens uliginosa to Copper Stress

Abstract

The phytoremediation of soil and water that has been significantly contaminated with metals has potential ecological and economical ramifications, as well as the advantages of high efficiency, and is an environmentally friendly method of ecological pollution control. This study aimed to examine the impact of varying concentrations of Copper (Cu2+) (0, 5, 10, 15, 20, and 25 mg·L−1) on the growth, development, physiology, biochemistry, mineral elements, and features of Cu2+ enrichment of Impatiens uliginosa. This plant is endemic to Yunnan Province in China and is a wetland species. The results showed that the root lengths, stem diameters, plant height, and stem and leaf biomass of I. uliginosa showed a phenomenon of “low promotion and high inhibition,” while the root biomass showed a trend of gradual decreasing. At the early stage of Cu2+ stress (day 6), the activities of peroxidase and catalase and the contents of malondialdehyde (MDA) of I. uliginosa were directly proportional to the concentration of Cu2+. As the treatment time increased, the activation of a defense mechanism in vivo enabled I. uliginosa to adapt to the high Cu2+ environment, and the content of MDA gradually decreased. As the concentration of Cu2+ increased, its contents in the roots, stems, and leaves also gradually increased. In particular, when the concentration of Cu2+ reached 25 mg·L−1, its contents in the roots of I. uliginosa increased by 39.16-fold compared with that of the control group (CK). The concentration-dependent influence of the contents of iron (Fe) and zinc (Zn) in the roots and leaves were observed. Low concentrations of Cu2+ promoted iron content in roots and leaves, and vice versa, while Zn content decreased with the increasing concentration of Cu2+. It was conclusively shown that I. uliginosa has the potential to remediate low concentrations of Cu2+ pollution in water and is a textbook ornamental plant to remediate bodies of water that are polluted with Cu2+.