Effect of cadmium and calcium treatments on phytochelatin and glutathione levels in citrus plants

• Published in: Plant biology (Stuttgart, Germany) Vol. 16; no. 1; pp. 79 - 87
• Main Authors: López-Climent, M. F., Arbona, V., Pérez-Clemente, R. M., Zandalinas, S. I., Gómez-Cadenas, A.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.01.2014
• Subjects: Abiotic stress; Cadmium - metabolism; Cadmium - pharmacology; cadmium toxicity; Calcium - metabolism; Calcium - pharmacology; Citrus - metabolism; Glutathione - metabolism; heavy metal; palliative treatment; Phytochelatins - metabolism; Plant Leaves - metabolism; Plant Roots - metabolism; cadmium toxicity; heavy metal; Abiotic stress; palliative treatment
• ISSN: 1435-8603; 1438-8677
• DOI: 10.1111/plb.12006

Industry residues, phosphate fertilisers and wastewater as a source of irrigation have considerably increased levels of heavy metals in the soil, mainly cadmium (Cd(2+)). To test the effects of a calcium (Ca(2+)) treatment on Cd(2+) accumulation and plant tolerance to this heavy metal, plants of two citrus genotypes, Cleopatra mandarin (CM) and Carrizo citrange (CC), were watered with increasing concentrations of Cd(2+), and phytochelatin (PC) and glutathione (GSH) content were measured. Both genotypes were able to synthesise PCs in response to heavy metal intoxication, although CM seems to be a better Cd(2+) excluder than CC. However, data indicate that CC plants had a higher capacity for regenerating GSH than CM plants. In this context, the effects of Ca(2+) treatment on Cd(2+) accumulation, plant survival and PC, GSH and oxidised glutathione (GSSG) content were assessed. Data indicate that treatment with Ca(2+) had two positive effects on citrus physiology: it reduced Cd(+2) uptake into roots and also increased GSH content (even in the absence of Cd(2+)). Overall, the data indicate that although Cd(2+) exclusion is a powerful mechanism to avoid heavy metal build-up into photosynthetic organs, the capacity to maintain optimum GSH levels to feed PC biosynthesis could also be an important factor in stress tolerance.