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Cadmium (Cd) is a non-essential heavy metal, toxic to all living organisms. The microtubule (MT) cytoskeleton appears to be one of the main targets of Cd action. In this study we present, with the use of various immunological approaches, the effect of Cd at moderate (85 μM) and high (170 μM) concentrations on the structure and functioning of the MT cytoskeleton in the root cells of soybean seedlings. As the result of heavy metal action, root growth was significantly diminished and was accompanied by a reduction in mitotic activity and disturbance in the structure of the MT arrays, including randomization of the cortical MT arrangement, distorted mitotic arrays and complete depolymerization of the MTs. Biochemical analysis revealed decreased levels of various α- and β-tubulin isoforms with a parallel down-regulation of most examined α-tubulin genes. Simultaneously, Cd treatment led to differentiated changes in the level of tubulin post-translational modifications, including tyrosination, detyrosination, acetylation, and polyglutamylation. Decreased tyrosination and polyglutamylation of particular tubulin isoforms accompanied by increase in the level of specific detyrosinated and acetylated isoforms implies augmented stability and reduced turnover of the MTs during stress conditions. Taken together, the obtained results indicate the significant impact of Cd on gene expression levels and subsequent post-translational processing of tubulin, which may be related to the impairment of MT cytoskeleton functioning in root cells.

The effect of lead, cadmium and cooper on protein pattern, free radicals and antioxidant enzymes in root of Lupinus luteus L.were investigated. Heavy metals inhibited growth of lupin roots, which was accompanied by increased synthesis and accumulation of a 16 kDa polypeptide (Przymusifiski et al. 1991 Biochem. Physiol. Pflanzen., 187:51-57). This component has been earlier identified as immtmologically related to Cu,Znsuperoxide dismutase (Przymusifiski etal. 1995 Env.Exp.Bot.,

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Previously, a stable cell suspension culture of cucumber tolerant to cadmium (Cd) was established (Gzyl and Gwóźdź, Plant Cell Tissue Organ Cult 80:59-67, 2005). In this study, ultrastructures of Cd-tolerant and -sensitive cells were analyzed by transmission electron microscopy (TEM). Ultrastructural differences between cell lines exposed to 100 lM CdCl 2 were observed both at cellular and organelle levels. Tolerant cells exposed to Cd exhibited well-preserved cellular structures in comparison with sensitive cells. Increased numbers of osmiophilic globules in the cytoplasm and nucleolus-associated bodies as well as electron dense material in vacuoles were observed in cadmium tolerant cells. In contrast, ultrastructure of sensitive cells following exposure to Cd exhibited distinct disturbances including vacuolation, disintegration of cytoplasm, and structural changes in both mitochondria and endoplasmic reticulum. TEM observations confirmed the adaptation of tolerant cells to Cd.