Barrier function of the cell wall during uptake of nickel ions

Russian Journal of Plant Physiology (Impact Factor: 0.95). 05/2011; 58(3):409-414. DOI: 10.1134/S1021443711030137


Cell walls were isolated from roots of six plant species to study their ion-exchange capacity for nickel ions (S
Ni) at Ni2+ concentration of 10−3 M. The S
Ni values varied depending on the plant species from 50 to 150 μmol Ni2+ per gram dry wt; the sorption capacity increased in a row: Poaceae < Chenopodiaceae < Fabaceae. At pH 5 the sorption capacity
of cell walls for nickel ions was determined by the presence of carboxyl groups of polygalacturonic acid in the polymeric
cell-wall matrix. In all cases the ion-exchange capacity of cell walls was higher at pH 8 than at pH 5, indicating that Ni2+ binds also to a carboxyl group different from that of polygalacturonic acid. Irrespective of plant species, the presence
of EDTA in the solution diminished drastically the absorption capacity of cell walls for Ni2+. It is concluded that the presence of 10−3 M EDTA weakens the defense properties of cell walls. The sequestration of Ni2+ in the cell wall can be considered as an effective means of plant cell defense against elevated concentrations of nickel
ions in the external medium.

Keywordshigher plants–cell walls–nickel ions–carboxyl groups–EDTA

Download full-text


Available from: Nataly Robertovna Meychik
  • Source
    • "The cell walls can work as a barrier and effectively sequestrate heavy metal ions (Macfie and Welbourn 2000; Latha et al. 2005; Meychik et al. 2011). Therefore, the cell walls could be a key factor in heavy metal exclusion mechanisms for fungi. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Our objective was to understand the cadmium (Cd) tolerance mechanisms by investigating the subcellular distribution, chemical forms of Cd and adsorptive groups in the mycelia of Exophiala pisciphila. We grew E. pisciphila in the liquid media with increasing Cd concentrations (0, 25, 50, 100, 200, and 400 mg L(-1)). Increased Cd in the media caused a proportional increase in the Cd uptake by E. pisciphila. Subcellular distribution indicated that 81 to 97 % of Cd was associated with the cell walls. The largest amount and proportion (45-86 %) of Cd was extracted with 2 % acetic acid, and a concentration-dependent extraction was observed, both of which suggest that Cd-phosphate complexes were the major chemical form in E. pisciphila. A large distribution of phosphate and Cd on the mycelia surface was observed by scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). The precipitates associated with the mycelia were observed to contain Cd by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX). Fourier transform infrared (FTIR) identified that hydroxyl, amine, carboxyl, and phosphate groups were responsible for binding Cd. We conclude that Cd associated with cell walls and integrated with phosphate might be responsible for the tolerance of E. pisciphila to Cd.
    Full-text · Article · Jul 2015 · Environmental Science and Pollution Research
  • Source
    • "In the intine putative binding sites for Ni are mostly the carboxyl groups of uronic acids; in the exine—the carboxyl groups of hydroxycinnamic acids (Meychik et al. 2006). These data suggest that the massive wall of the pollen grains may, like the walls of somatic cells (Meychik et al. 2011), perform a barrier function to protect the protoplast from the toxic effect of Ni 2? . On the other hand, it may act as a target. "
    [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the mechanisms of Ni(2+) effects on initiation and maintenance of polar cell growth, we used a well-studied model system-germination of angiosperm pollen grains. In liquid medium tobacco pollen grain forms a long tube, where the growth is restricted to the very tip. Ni(2+) did not prevent the formation of pollen tube initials, but inhibited their subsequent growth with IC(50) = 550 μM. 1 mM Ni(2+) completely blocked the polar growth, but all pollen grains remained viable, their respiration was slightly affected and ROS production did not increase. Addition of Ni(2+) after the onset of germination had a bidirectional effect on the tubes development: there was a considerable amount of extra-long tubes, which appeared to be rapidly growing, but the growth of many tubes was impaired. Studying the localization of possible targets of Ni(2+) influence, we found that they may occur both in the wall and in the cytoplasm, as confirmed by specific staining. Ni(2+) disturbed the segregation of transport vesicles in the tips of these tubes and significantly reduced the relative content of calcium in the aperture area of pollen grains, as measured by X-ray microanalysis. These factors are considered being critical for normal polar cell growth. Ni(2+) also causes the deposition of callose in the tips of the tube initials and the pollen tubes that had stopped their growth. We can assume that Ni(2+)-induced disruption of calcium homeostasis can lead to vesicle traffic impairment and abnormal callose deposition and, consequently, block the polar growth.
    Full-text · Article · Sep 2012 · Biology of Metals