Integrated Ca, Mg, Cu, and Zn supply upregulates leaf anatomy and metabolic adjustments in Eucalyptus seedlings.

Adaptive responses to abiotic stresses such as soil acidity in Eucalyptus-the most widely planted broad-leaf forest genus globally-are poorly understood. This is particularly evident in physiological and anatomical disorders that inhibit plant development and wood quality. We aimed to explore how the supply of Ca and Mg through liming (lime), combined with Cu and Zn fertilization (CZF), influences physiological and anatomical responses during Eucalyptus grandis seedlings growth in tropical acid soil. Therefore, related parameters of leaf area and leaf anatomy, stomatal size, leaf gas exchange, antioxidant system, nutrient partitioning, and biomass allocation responses were monitored. Liming alone in Eucalyptus increased specific leaf area, stomatal density on the abaxial leaf surface, and Ca and Mg content. Also, Eucalyptus exposed only to CZF increased Cu and Zn content. Lime and CZF increased leaf blade and adaxial epidermal thickness, and improved the structural organization of the spongy mesophyll, promoting increased net CO2 assimilation, and stomatal conductance. Fertilization with Ca, Mg, Cu, and Zn positively affects plant nutrition, light utilization, photosynthetic rate, and antioxidant performance, improving growth. Our results indicate that lime and CZF induce adaptive responses in the physiological and anatomical adjustments of Eucalyptus plantation, thereby promoting biomass accumulation.

Cadmium tolerance in tomato: determination of organ-specific contribution by diallel analysis using reciprocal grafts.

Given the increasing problems of water and soil contamination with cadmium (Cd), it is necessary to investigate the genetic and physiological mechanisms of tolerance to this metal in different crops, which can be used for the development of effective crop management strategies. This study aimed to assess the potential of grafting as a strategy to increase Cd tolerance and reduce absorption in tomato by evaluating the contribution of the root system and aerial parts for tolerance mechanisms. To this end, reciprocal grafting and diallel analyses were used to examine the combining ability of contrasting tomato genotypes under exposure to 0 and 35 µM CdCl2. Roots and above-ground parts were found to have specific mechanisms of Cd tolerance, absorption, and accumulation. Grafting of the USP15 genotype (scion) on USP16 (rootstock) provided the greatest synergism, increasing the tolerance index and reducing the translocation index and Cd accumulation in leaves. USP163 exhibited potential for breeding programs that target genotypes with high Cd tolerance. In tomato, both Cd tolerance and accumulation in aerial parts are genotype- and tissue-specific, controlled by a complex system of complementary mechanisms that need to be better understood to support the development of strategies to reduce Cd contamination in aerial parts.

Toxicity of bisphenol A (BPA) and its analogues BPF and BPS on the free-floating macrophyte Salvinia biloba.

Evidence linking the toxicity of bisphenol A (BPA) to environmental and public-health issues has led to restrictions on its use. This compound has been gradually replaced with analogues proposed as a safer alternative, normally bisphenol F (BPF) and bisphenol S (BPS), but these substitutes are structurally almost identical to BPA, suggesting they may pose similar risks. The effects of BPA and these analogues were compared for antioxidant activity, lipid peroxidation, free-radical generation, photosynthetic pigments, and chlorophyll fluorescence in Salvinia biloba Raddi (S. biloba) plants exposed to environmentally relevant and sublethal concentrations (1, 10, 50, 100 and 150 µM). Bisphenol exposure promoted alterations in most of the physiological parameters investigated, with BPS toxicity differing slightly from that of the analogues. Furthermore, S. biloba removed similar levels of BPA and BPF from aqueous solutions with ≈70% removed at the 150 µM concentration, while BPS was less effectively removed, with only 23% removed at 150 µM. These findings show that high concentrations of bisphenols (10≥) are toxic to S. biloba, and even typical environmental levels (≤1 µM) can induce metabolic changes in plants, bringing to light that both BPA and its substitutes BPF and BPS pose risks to aquatic ecosystems.

Mechanisms of Mucor sp. CM3 isolated from the aquatic macrophyte Eichhornia crassipes (Mart.) Solms to increase cadmium bioremediation.

Bioremediation of toxic metals is a feasible and low-cost remediation tool to reduce metal contamination. Plant-fungus interactions can improve this technique. Eichhornia crassipes (Mart.) Solms is a macrophyte reported to bioremediate contaminated water. Thus, the present study aimed to isolate endophytic fungi from E. crassipes, select a highly cadmium (Cd) tolerant isolate and evaluate its bioremediation potential. This was evaluated by (1) the fungus tolerance and capacity to accumulate Cd; (2) Cd effects on cell morphology (using SEM and TEM) and on the fungal antioxidant defense system, as well as (3) the effect on model plant Solanum lycopersicum L. cultivar Calabash Rouge, inoculated with the endophyte fungus and exposed to Cd. Our results selected the endophyte Mucor sp. CM3, which was able to tolerate up to 1000 g/L of Cd and to accumulate 900 mg of Cd/g of biomass. Significant changes in Mucor sp. CM3 morphology were observed when exposed to high Cd concentrations, retaining this metal both in its cytoplasm and in its cell wall, which may be linked to detoxification and metal sequestration mechanisms related to the formation of Cd-GSH complexes. In addition, Cd stress induced the activation of all tested antioxidant enzymes - superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) - in this endophytic fungus. Moreover, when inoculated in tomato plants, this fungus promoted plant growth (in treatments without Cd) and induced an increased metal translocation to plant shoot, showing its potential to increase metal bioremediation. Therefore, this study indicates that the isolated endophyte Mucor sp. CM3 can be applied as a tool in different plant conditions, improving plant bioremediation and reducing the environmental damage caused by Cd, while also promoting plant growth in the absence of contaminants.

Grafting systems for plant cadmium research: Insights for basic plant physiology and applied mitigation.

Cadmium (Cd) is a highly toxic and carcinogenic pollutant that poses a threat to human and animal health by affecting several major organ systems. Urbanization and human activities have led to significant increases in Cd concentration in the environment, including in agroecosystems. To protect against the harmful effects of Cd, efforts are being made to promote safe crop production and to clean up Cd-contaminated agricultural lands and water, reducing Cd exposure through the consumption of contaminated agricultural products. There is a need for management strategies that can improve plant Cd tolerance and reduce Cd accumulation in crop plant tissues, all of which involve understanding the impacts of Cd on plant physiology and metabolism. Grafting, a longstanding plant propagation technique, has been shown to be a useful approach for studying the effects of Cd on plants, including insights into the signaling between organs and organ-specific modulation of plant performance under this form of environmental stress. Grafting can be applied to the large majority of abiotic and biotic stressors. In this review, we aim to highlight the current state of knowledge on the use of grafting to gain insights into Cd-induced effects as well as its potential applicability in safe crop production and phytoremediation. In particular, we emphasize the utility of heterograft systems for assessment of Cd accumulation, biochemical and molecular responses, and tolerance in crop and other plant species under Cd exposure, as well as potential intergenerational effects. We outline our perspectives and future directions for research in this area and the potential practical applicability of plant grafting, with attention to the most obvious gaps in knowledge. We aim at inspiring researchers to explore the potential of grafting for modulating Cd tolerance and accumulation and for understanding the mechanisms of Cd-induced responses in plants for both agricultural safety and phytoremediation purposes.

New insights into cadmium tolerance and accumulation in tomato: Dissecting root and shoot responses using cross-genotype grafting.

Cadmium (Cd) is one of the most threatening soil and water contaminants in agricultural settings. In previous studies, we observed that Cd affects the metabolism and physiology of tomato (Solanum lycopersicum) plants even after short-term exposure. The objective of this research was to use cross-genotype grafting to distinguish between root- and shoot-mediated responses of tomato genotypes with contrasting Cd tolerance at the early stages of Cd exposure. This study provides the first report of organ-specific contributions in two tomato genotypes with contrasting Cd tolerance: Solanum lycopersicum cv. Calabash Rouge and Solanum lycopersicum cv. Pusa Ruby (which have been classified and further characterized as sensitive (S) and tolerant (T) to Cd, respectively). Scion S was grafted onto rootstock S (S/S) and rootstock T (S/T), and scion T was grafted onto rootstock T (T/T) and rootstock S (T/S). A 35 µM cadmium chloride (CdCl2) treatment was used for stress induction in a hydroponic system. Both shoot and root contributions to Cd responses were observed, and they varied in a genotype- and/or organ-dependent manner for nutrient concentrations, oxidative stress parameters, antioxidant enzymes, and transporters gene expression. The findings overall provide evidence for the dominant role of the tolerant rootstock system in conferring reduced Cd uptake and accumulation. The lowest leaf Cd concentrations were observed in T/T (215.11 µg g-1 DW) and S/T (235.61 µg g-1 DW). Cadmium-induced decreases in leaf dry weight were observed only in T/S (-8.20%) and S/S (-13.89%), which also were the only graft combinations that showed decreases in chlorophyll content (-3.93% in T/S and -4.05% in S/S). Furthermore, the results show that reciprocal grafting is a fruitful approach for gaining insights into the organ-specific modulation of Cd tolerance and accumulation during the early stages of Cd exposure.

Leaf 13C and 15N composition shedding light on easing drought stress through partial K substitution by Na in eucalyptus species.

This work aimed to investigate the partial K-replacement by Na supply to alleviate drought-induced stress in Eucalyptus species. Plant growth, leaf gas exchange parameters, water relations, oxidative stress (H2O2 and MDA content), chlorophyll concentration, carbon (C) and nitrogen (N) isotopic leaf composition (δ13C and δ15N) were analyzed. Drought tolerant E. urophylla and E. camaldulensis showed positive responses to the partial K substitution by Na, with similar dry mass yields, stomatal density and total stomatal pore area relative to the well K-supplied plants under both water conditions, suggesting that 50% of the K requirements is pressing for physiological functions that is poorly substituted by Na. Furthermore, E. urophylla and E. camaldulensis up-regulated leaf gas exchanges, leading to enhanced long-term water use efficiency (WUEL). Moreover, the partial K substitution by Na had no effects on plants H2O2, MDA, δ13C and δ15N, confirming that Na, to a certain extent, can effectively replace K in plants metabolism. Otherwise, the drought-sensitive E. saligna species was negatively affected by partial K replacement by Na, decreasing plants dry mass, even with up-regulated leaf gas exchange parameters. The exclusive Na-supplied plants showed K-deficient symptoms and lower growth, WUEL, and δ13C, besides higher Na accumulation, δ15N, H2O2 and MDA content.

Comparative phosphoproteomic analysis of tomato genotypes with contrasting cadmium tolerance.

KEY MESSAGE: A first insight into the effects of cadmium exposure on the phosphoproteome of tomato plants by performing a comparative analysis of tomato genotypes with contrasting cadmium tolerance.

Unravelling homeostasis effects of phosphorus and zinc nutrition by leaf photochemistry and metabolic adjustment in cotton plants.

Phosphorus (P) and zinc (Zn) uptake and its physiological use in plants are interconnected and are tightly controlled. However, there is still conflicting information about the interactions of these two nutrients, thus a better understanding of nutritional homeostasis is needed. The objective of this work was to evaluate responses of photosynthesis parameters, P-Zn nutritional homeostasis and antioxidant metabolism to variation in the P × Zn supply of cotton (Gossypium hirsutum L.). Plants were grown in pots and watered with nutrient solution containing combinations of P and Zn supply. An excess of either P or Zn limited plant growth, reduced photosynthesis-related parameters, and antioxidant scavenging enzymes. Phosphorus uptake favoured photochemical dissipation of energy decreasing oxidative stress, notably on Zn-well-nourished plants. On the other hand, excessive P uptake reduces Zn-shoot concentration and decreasing carbonic anhydrase activity. Adequate Zn supply facilitated adaptation responses to P deficiency, upregulating acid phosphatase activity, whereas Zn and P excess were alleviated by increasing P and Zn supply, respectively. Collectively, the results showed that inter ionic effects of P and Zn uptake affected light use and CO2 assimilation rate on photosynthesis, activation of antioxidant metabolism, acid phosphatase and carbonic anhydrase activities, and plant growth-related responses to different extents.

Cadmium-induced transgenerational effects on tomato plants: A gift from parents to progenies.

The present study aimed to investigate the Cd-induced transgenerational effects on plants. Grafted tomato plants, which exhibited the same cultivar as scion and distinct cultivars with contrasting Cd-tolerance as rootstocks, were grown in soil without and with artificial addition of Cd (less than 2.0, and 6.9 mg kg-1 of Cd, respectively) in a pot experiment carried out in a greenhouse. Their fruits were harvested to extract seeds (i.e., the progenies), which were sown over either Cd-free (control) or Cd-containing germitest paper (germination testing paper with 0 and 35 µM of CdCl2, respectively) and grown in a growth chamber. The immediate progeny of all grafting combinations from stressed plants presented an elevated germinability, despite high internal Cd concentration. When sown in Cd-containing germitest paper, the immediate progeny of plants grown in soil with no Cd addition was generally able to maintain or even increase the content of carotenoids and chlorophylls a and b (up to 93.3, 62.8 and 76.1%, respectively), indicating a Cd-induced hormetic effect on photosynthetic pigments. Two of the grafting combinations from stressed plants yielded seeds that generated seedlings with enhanced dry mass when they were sown in Cd-free media (~41%), suggesting a Cd-induced transgenerational enhancement of biomass production. Because only one tomato cultivar was used as scion, data indicated that type and degree of Cd-induced transgenerational effects depend strongly on signals generated and/or processed in roots of the parental plants. When sown in Cd-contaminated germitest paper, the immediate progeny of Cd-treated plants presented major reductions in the leaf area (35-69%) and content of photosynthetic pigments (57-93%) in comparison to the progeny from control plants. However, one of the grafting combinations exhibited satisfactory performance after "double" exposure to Cd, showing 91% of the biomass that was produced in the seedlings of control seeds from control plants. Further investigation indicated that adjustments in the chlorophyll fluorescence behavior might counterbalance losses in leaf pigments and area. Taken together, our data provide new insights on the origin, outcomes and mode of action of the Cd-induced transgenerational effects.

Tolerance of tomato to cadmium-induced stress: analyzing cultivars with different fruit colors.

The objective of the present study was to assess the response of tomato cultivars with different fruit colors to exposure to increasing Cd levels in the substrate by measuring the impacts of Cd on the oxidative stress indicators and physicochemical features of fruits, as well as plant development and yield components. A completely randomized experiment in a 3 × 3 factorial design [tomato cultivar (which produces purple, red, or white fruits) vs Cd level in the substrate (0, 3.6, or 12 mg kg-1)] was performed. The cultivation of plants in substrate containing 3.6 mg kg-1 Cd did not affect yield, but fruits exhibited nonpermissive Cd concentrations in both peel and mesocarp across all cultivars. By contrast, yield was decreased in plants with red and white fruits after their cultivation in substrate containing 12 mg kg-1 Cd, while the productivity of plants with purple fruits was maintained under such conditions. The hydrogen peroxide content in the fruit mesocarp depended only on cultivar. However, an increased lipid peroxidation level was detected in the mesocarp of purple fruits at the highest Cd concentration. No parameters of fruit quality [i.e., diameter, length, °Brix, pH, titratable acidity, color (L*, a*, and b*), and concentrations of lycopene and ß-carotene in mesocarp] were affected by long-term exposure to Cd at 12 mg kg-1. In conclusion, the results of this study suggested that the potential Cd side effects on diverse tomato quality features can be buffered at the fruit level because these features were maintained at the usual values despite high Cd concentrations in tomato peel and pulp. Moreover, these buffering mechanisms are independent of lycopene and ß-carotene concentrations in fruit peel, since the three tomato cultivars that were evaluated in the present study (white fruits, possessing no or negligible concentrations of these carotenoids, and red and purple tomato, possessing high lycopene and ß-carotene concentrations) were able to sustain several fruit quality parameters after long-term exposure to high Cd concentrations in the substrate.

Unraveling the mechanisms controlling Cd accumulation and Cd-tolerance in Brachiaria decumbens and Panicum maximum under summer and winter weather conditions.

We evaluated the mechanisms that control Cd accumulation and distribution, and the mechanisms that protect the photosynthetic apparatus of Brachiaria decumbens Stapf. cv. Basilisk and Panicum maximum Jacq. cv. Massai from Cd-induced oxidative stress, as well as the effects of simulated summer or winter conditions on these mechanisms. Both grasses were grown in unpolluted and Cd-polluted Oxisol (0.63 and 3.6 mg Cd kg-1 soil, respectively) at summer and winter conditions. Grasses grown in the Cd-polluted Oxisol presented higher Cd concentration in their tissues in the winter conditions, but the shoot biomass production of both grasses was not affected by the experimental conditions. Cadmium was more accumulated in the root apoplast than the root symplast, contributing to increase the diameter and cell layers of the cambial region of both grasses. Roots of B. decumbens were more susceptible to disturbed nutrients uptake and nitrogen metabolism than roots of P. maximum. Both grasses translocated high amounts of Cd to their shoots resulting in oxidative stress. Oxidative stress in the leaves of both grasses was higher in summer than winter, but only in P. maximum superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities were increased. However, CO2 assimilation was not affected due to the protection provided by reduced glutathione (GSH) and phytochelatins (PCs) that were more synthesized in shoots than roots. In summary, the root apoplast was not sufficiently effective to prevent Cd translocation from roots to shoot, but GSH and PCs provided good protection for the photosynthetic apparatus of both grasses.

Mechanisms of cadmium-stress avoidance by selenium in tomato plants.

Cadmium (Cd) is probably the most damaging metal to plant species; with a long biological half-life, it can be taken up by plants, disrupting the cell homeostasis and triggering several metabolic pathways. Selenium (Se) improves plant defence systems against stressful conditions, but the biochemical antioxidant responses to Cd stress in tomato plants is poorly understood. To further address the relationship of Cd-stress responses with Se mineral uptake, Cd and Se concentration, proline content, MDA and H2O2 production, and the activity of SOD, APX, CAT and GR enzymes were analyzed in Micro-Tom (MT) plants submitted to 0.5 mM Cd. The results revealed different responses according to Se combination and Cd application. For instance, roots and leaves of MT plants treated with Se exhibited an increase in dry mass and nutritional status, exhibited lower proline content and higher APX and GR activities when compared with plants with no Se application. Plants submitted to 0.5 mM Cd, irrespective of Se exposure, exhibited lower proline, MDA and H2O2 content and higher SOD, CAT and GR activities. Selenium may improve tolerance against Cd, which allowed MT plants exhibited less oxidative damage to the cell, even under elevated Cd accumulation in their tissues. The results suggest that Se application is an efficient management technique to alleviate the deleterious effects of Cd-stress, enhancing the nutritional value and activity of ROS-scavenging enzymes in tomato plants.

Foliar application of 24-epibrassinolide improves Solanum nigrum L. tolerance to high levels of Zn without affecting its remediation potential.

Although Solanum nigrum L. is a phytoremediator for different metals, its growth and physiology are still compromised by toxic levels of zinc (Zn). Thus, the development of eco-friendly strategies to enhance its tolerance, maintaining remediation potential is of special interest. This study evaluated the potential of 24-epibrassinolide (24-EBL) to boost S. nigrum defence against Zn towards a better growth rate and remediation potential. After 24 days of exposure, the results revealed that Zn-mediated inhibitory effects on biomass and biometry were efficiently mitigated upon application of 24-EBL, without affecting Zn accumulation. The evaluation of oxidative stress markers reported that Zn excess stimulated the accumulation of superoxide anion (O2.-), but reduced hydrogen peroxide (H2O2) levels, while not altering lipid peroxidation (LP). This was accompanied by an up-regulation of the antioxidant system, especially proline, superoxide dismutase (SOD) and ascorbate peroxidase (APX) in both organs, and ascorbate in roots of Zn-exposed plants. Foliar application of 24-EBL, however, induced distinctive effects, lowering proline levels in both organs, as well as APX activity in shoots and SOD in roots, whilst stimulating GSH and total thiols in both organs, as well as SOD and APX activity, in shoots and in roots, respectively. Probably due to a better antioxidant efficiency, levels of O2.- and H2O2 in pre-treated plants remained identical to the control, while LP further decreased in shoots. Overall, our results indicate a protective effect of 24-EBL on S. nigrum response to excess Zn, contributing for a better tolerance and growth rate, without disturbing its phytoremediation potential.

Aluminum-induced toxicity in Urochloa brizantha genotypes: A first glance into root Al-apoplastic and -symplastic compartmentation, Al-translocation and antioxidant performance.

Previous studies have unraveled contrasting Al genotypic differences between Urochloa brizantha cv. Marandu (moderately tolerant) and Urochloa brizantha cv. Xaraés (more tolerant). Our objective was to evaluate differences in the response to Al-induced stress between these genotypes, focusing on Al compartmentation in the root apoplast and symplast, and antioxidant enzyme activities after Al exposure. Al-accumulation was 25% higher in the roots of cv. Xaraés than cv. Marandu, while in the shoot Al accumulation was 150% higher in cv. Marandu than cv. Xaraés. U. brizantha cv. Marandu accumulated 73% of the Al absorbed in the root symplast and 27% in the root apoplast, while cv. Xaraés accumulated 61% of the Al absorbed in symplast and 39% in apoplast. Furthermore, Al exposure leaded to physiological and developmental changes in root morphology, such as disorganization of vascular system, the collapse of cortical cells and absence of root hairs from the root tip, with more drastic effects detectable in cv. Marandu. Catalase (CAT) and guaiacol peroxidase (GPOX) activities in the roots of cv. Marandu were lower compared to cv. Xaraés. Our results pointed out that higher Al compartmentalization rates in the root apoplast, altogether with up-regulated metabolic activities of CAT and GPOX and also lower long distance transport of Al are seemingly at the base of the Al tolerance in cv. Xaraés. In conclusion, biochemical analysis of roots suggested that understanding of metabolic pathways is one of pressing approach to elucidate stress tolerance mechanisms in this genus.

New insights into cadmium stressful-conditions: Role of ethylene on selenium-mediated antioxidant enzymes.

Cadmium (Cd) contamination has generated an environmental problem worldwide, leading to harmful effects on human health and damages to plant metabolism. Selenium (Se) is non essential for plants, however it can improve plant growth and reduce the adverse effects of abiotic stress. In addition, ethylene may interplay the positive effects of Se in plants. In order to investigate the role of ethylene in Se-modulation of antioxidant defence system in response to Cd-stress, we tested the hormonal mutant Epinastic (epi) with a subset of constitutive activation of the ethylene response and Micro-Tom (MT) plants. For this purpose, Se mineral uptake, Cd and Se concentrations, pigments, malondialdeyde (MDA) and hydrogen peroxide (H2O2) contents, ethylene production, glutathione (GSH) compound, and superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GSH-Px) activities were analysed in MT and epi plants submitted to 0.5 mM CdCl2 and 1 µM of selenate or selenite. MT plants treated with both Se forms increased growth in the presence or not of 0.5 mM CdCl2, but not change epi growth. Both Se forms reduced Cd uptake in MT plants and cause reverse effect in epi plants. P, Mg, S, K and Zn uptake increased in epi plants with Se application, irrespective to Cd exposure. Chlorophylls and carotenoids contents decreased in both genotypes under Cd exposure, in contrast to what was observed in epi leaves in the presence of Se. When antioxidant enzymes activities were concerned, Se application increased Mn-SOD, Fe-SOD and APX activities. In the presence of Cd, MT and epi plants exhibited decreased SOD activity and increased CAT, APX and GR activities. MT and epi plants with Se supply exhibited increased APX and GR activities in the presence of Cd. Overall, these results suggest that ethylene may be involved in Se induced-defence responses, that triggers a positive response of the antioxidant system and improve growth under Cd stress. These results showed integrative roles of ethylene and Se in regulating the cell responses to stressful-conditions and, the cross-tolerance to stress could be used to manipulate ethylene regulated gene expression to induce heavy metal tolerance.

Cadmium toxicity and its relationship with disturbances in the cytoskeleton, cell cycle and chromosome stability.

This study aimed to investigate the mode of action of cadmium (Cd) toxicity at cell level, especially at early stages of plant exposure. Tomato seedlings were cultivated in growth media containing from 0.1 to 70 µM CdCl2 for 24 h. Mitotic index, chromosome abnormality, DNA integrity and organization of tubulin-based structures were assessed in root cells. As higher the Cd concentration in the growth media, higher was the DNA damage intensity and the occurrence of chromosomal abnormalities that included chromosome lost, bridges, stickiness, C-metaphase and polyploidy. The profile of chromosomal aberrations also varied with elevated Cd concentration, being observed increases in the frequency of chromosome stickiness. The mitotic index was reduced at the lowest Cd concentration, but such reduction was statistically similar to that detected at the highest concentration, suggesting that mitotic depression is a rapid outcome and, at same time, a Cd-induced effect that is limited at the first 24 h of direct root exposure to this metal. Under exposure to 20 µM CdCl2, heterogenous distribution of the spindle fibers, formation of two spindle complexes in both of the cell poles, absence of centrosome center, polarization of the spindle fibers during cell division, and non-uniform tubulin deposition in microtubule and phragmoplast were noticed. The results indicate that the tubulin-dependent components of cytoskeleton are Cd targets, and the sensitivity of tubulin-based structures to Cd exposure depends on cell cycle phase. Moreover, DNA damage intensity and chromosomal abnormality profile can be employed as markers of Cd toxicity level.