Fiziol. rast. genet. 2022, vol. 54, no. 4, 279-310, doi:

Cadmium stress in plants: toxicity and resistance mechanisms

Levenets T.V.1, Smirnov O.E.1.2, Taran N.Yu.1, Mykhalska L.M.2, Schwartau V.V.2

  1. Educational and Scientific Centre «Institute of Biology and Medicine» of Taras Shevchenko Kyiv National University  64/13, Volodymyrska St., Kyiv, 01601, Ukraine
  2. Institute of Plant Physiology and Genetics, National Academy of Sciences of Ukraine 31/17, Vasylkivska St., Kyiv, 03022, Ukraine

Increasing levels of cadmium contamination of ecocenoses, primarily due to the application of phosphorus fertilizers and industrial activity requires research into the mechanisms of manifestation of its toxicity for plants at all levels of the organization of the plant organism, starting from the general morpho-anatomical changes of individual organs to the regulation of gene expression of individual proteins. Differences in the ability of different species, varieties and individual representatives within populations to absorb, accumulate, translocate and redistribute cadmium, as well as the difference in the degree of their Cd-tolerance in practice, very often turns out to be related to the presence or absence, features of the structure, expression and localization certain transporters of the element. Mechanisms of regulation of the toxic effect of cadmium on plants at the cellular level are considered. It has been shown that plants resistant to cadmium are able to limit the absorption of the element and/or have powerful systems for its detoxification. Such plants direct a part of the pool of assimilated carbon to the root secretion of organic compounds that chelate the toxic element. The translocation of cadmium from roots to shoots is inhibited in the endoderm zone. After the element enters the cell, plants use various mechanisms to detoxify cadmium. Synthesis of metal-chelating peptides or Cys-proteins in plants that bind to cadmium and reduce its toxicity is important. Another mechanism of detoxification is realized by the regulation of cadmium transport through the plasma membrane and tonoplast. Antioxidants and cellular antioxidant activity are also important in increasing plant resistance to cadmium. Expression of genes that encode enzymes involved in the repair of ROS-induced damage increases tolerance to cadmium. Thus, it is shown that the increase in the levels of cadmium contamination of ecocenoses, primarily due to the application of phosphorus fertilizers and industrial activity, forms a dangerous factor of toxic effects on plants. The development of an adaptive response to cadmium stress is a complex phenomenon and manifests itself at all levels of the organization of the plant organism. Generalization of data on stress mechanisms singles out the features of cadmium impact and its localization in plant tissues, as well as ways of forming resistance to cadmium. The presented material can be the basis for controlling the phytotoxicity of cadmium, developing approaches to phytoremediation, and forming ecologically safe agrophytocenoses.

Keywords: cadmium, stress, phytotoxicity, mechanisms of resistance, phytoremediation

Fiziol. rast. genet.
2022, vol. 54, no. 4, 279-310

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