Ecotoxicological and Interactive Effects of Copper and Chromium on Physiochemical, Ultrastructural, and Molecular Profiling in Brassica napus L.

Abstract

Heavy metal accumulation causes huge environmental problems, particularly in agricultural ecosystems which have deteriorative effects on the yield and quality of crops. Individual copper (Cu) and chromium (Cr) effects have been investigated extensively in plants; however, co-contamination of Cu and Cr induced stress on Brassica napus L. is still unclear. In the present experiment, the interactive effects of Cu and Cr were studied in two B. napus cultivars (Zheda 622 and ZS 758). Results showed that the application of Cr was more toxic than Cu, and their combined stress had shown a significant adverse effect on plant growth. Biomass and photosynthetic pigment were decreased remarkably under all metal treatments. Individual treatments of Cu and Cr and their combination cause the accumulation of ROS and lipid peroxidation. Moreover, the activities of antioxidant enzymes and their mRNA transcription levels, such as catalase (CAT), ascorbate peroxidase, glutathione reductase, superoxide dismutase, and peroxidase, were increased, especially when treated with Cr alone or under Cu+Cr combined treatment in both cultivars, except for the CAT activity which was decreased in both leaves and roots of sensitive cultivar Zheda 622 as compared with their respective controls. Additionally, nonenzymatic antioxidants like reduced and oxidized glutathione showed a differential activity pattern in roots and leaves of both cultivars. A more pronounced modification in chloroplast ultrastructure was observed in both cultivars under Cu+Cr treatment followed by Cr and Cu alone treatments. Furthermore, synergistic effects of Cu and Cr were prominent; this may be due to the enhanced metals uptake under combined treatment, which suggests that Cr and Cu interaction is not competitive but is rather additive and genotypic-dependent.

Copper Uptake and Accumulation, Ultra-Structural Alteration, and Bast Fibre Yield and Quality of Fibrous Jute (Corchorus capsularis L.) Plants Grown under Two Different Soils of China

“…The most common impact of Cu stress is a decrease in photosynthetic pigments in the leaves. Moreover, a decrease in photosynthesis activity and alteration in the ultrastructure of the chloroplast is directly linked with photosynthetic pigments in the leaves [11,15]. Total chlorophyll (chl a and b) is also affected by toxic Cu level in the soil.…”

“…Cu is a micronutrient, and excess Cu concentration is toxic to plants. Excess Cu in the soil causes alterations in DNA and cell membrane integrity, ultimately reducing plant growth and biomass [9][10][11][12]. Phytotoxicity of Cu causes membrane damage through binding of Cu to the sulfhydryl groups of membrane proteins.…”

“…Furthermore, normal concentration of Cu is nontoxic to plants, whereas Cu toxicity directly disturbs the structure of chloroplast, mitochondrial apparatus, nucleus, and other cellular organelles [6,7,13,14]. Excess Cu causes damage to the cellular membrane organelles by increasing ROS in plant cells and tissues, causing peroxidation of substances on the cell surface [11,[15][16][17]. ROS, which are toxic and remove by the activities of antioxidant compounds [18][19][20][21][22][23].…”

Flax (Linum usitatissimum L.): A Potential Candidate for Phytoremediation? Biological and Economical Points of View

“…They decrease the growth and development of plants even at low concentrations of heavy metals with respect to other metals. Excess amounts of other metals or elements do not damage the tissues/cells of the plant, and their accumulation can even increase the growth of the plant [7][8][9][10][11]. The metals which are lethal or harmful for plants include: lead, cadmium, cobalt, iron, silver, platinum, nickel, chromium, copper, and zinc.…”

“…Another method for the removal of toxic substances like heavy metals is "hyper accumulation," which is widely used and uses the genetic potential of the roots of plants originating from contaminated areas [9,36]. Different plants have different methods for the removal and accumulation of different substances like nutrients and organic materials.…”