Altered physiology, cell structure, and gene expression of Theobroma cacao seedlings subjected to Cu toxicity

• Published in: Environmental science and pollution research international 2014, Vol.21 (2), p.1217-1230
• Main Authors: Souza, Vânia L, de Almeida, Alex-Alan F, de S. Souza, Jadiel, Mangabeira, Pedro A. O, de Jesus, Raildo M, Pirovani, Carlos P, Ahnert, Dário, Baligar, Virupax C, Loguercio, Leandro L
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Cacao - cytology; Cacao - genetics; Cacao - physiology; Cell membranes; Chemical analysis; Chloroplasts; Cocoa; Copper; Copper - toxicity; Cultivars; Dietary minerals; Earth and Environmental Science; Ecotoxicology; Electrolyte leakage; Electrolytic cells; Environment; Environmental Chemistry; Environmental Health; Enzymes; Fungicides; Gas exchange; Gene expression; Gene Expression - drug effects; genotype; Genotypes; greenhouses; Heavy metal content; Heavy metals; iron; Leaves; Lipid peroxidation; Lipids; manganese; Membranes; Mesophyll; Metabolism; Nutrient concentrations; Nutrients; Peroxidation; Pesticides; Photosynthesis; Physiology; Phytotoxicity; Plasmolysis; Proteins; Research Article; Roots; Seedlings; Seedlings - cytology; Seedlings - genetics; Seedlings - metabolism; shoots; Soil contamination; Soil Pollutants - toxicity; Stress, Physiological; Studies; Theobroma cacao; Thiobarbituric acid; thiobarbituric acid-reactive substances; Thylakoids; Toxicity; Ultrastructure; Waste Water Technology; Water Management; Water Pollution Control; zinc
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-013-1983-4

Seedlings of Theobroma cacao CCN 51 genotype were grown under greenhouse conditions and exposed to increasing concentrations of Cu (0.005, 1, 2, 4, 8, 16, and 32 mg Cu L⁻¹) in nutrient solution. When doses were equal or higher than 8 mg Cu L⁻¹, after 24 h of treatment application, leaf gas exchange was highly affected and changes in chloroplasts thylakoids of leaf mesophyll cells and plasmolysis of cells from the root cortical region were observed. In addition, cell membranes of roots and leaves were damaged. In leaves, 96 h after treatments started, increases in the percentage of electrolyte leakage through membranes were observed with increases of Cu in the nutrient solution. Moreover, there was an increase in the concentration of thiobarbituric acid-reactive substances in roots due to lipid peroxidation of membranes. Chemical analysis showed that increases in Cu concentrations in vegetative organs of T. cacao increased with the increase of the metal in the nutrient solution, but there was a greater accumulation of Cu in roots than in shoots. The excess of Cu interfered in the levels of Mn, Zn, Fe, Mg, K, and Ca in different organs of T. cacao. Analysis of gene expression via RTq-PCR showed increased levels of MT2b, SODCyt, and PER-1 expression in roots and of MT2b, PSBA, PSBO, SODCyt, and SODChI in leaves. Hence, it was concluded that Cu in nutrient solution at doses equal or above 8 mg L⁻¹ significantly affected leaf gas exchange, cell ultrastructure, and transport of mineral nutrients in seedlings of this T. cacao genotype.