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To study the adaptive potential of the plant Typha laxmannii Lepech. to heavy metal (HM) stress on the basis of analysis of its morphological and anatomical features under the conditions of an anthropogenically transformed ecosystem of the Don River Delta. The soils on the monitored plots are of the Fluvisol type. The soil characteristics and total concentrations of Mn, Ni, Cd, Cu, Zn, Pb and Cr in soils and cattail plants were analysed. Anatomical-morphological and electron-microscopic examinations revealed the toxic effect of HMs on the roots and leaves of T. laxmannii plants. The studied soils were found to contain high levels of the Zn, Cr, Pb and Cu. It was shown that the sources of Zn, Pb and Cu in the soils were anthropogenic in nature. The high Cr level in soils was due to the natural lithogenic factor. The contents of HM mobile forms in the soils exceeded the maximum permissible concentrations of Cd, Zn, Pb and Ni. An examination of communities of T. laxmannii grown in the impact zone revealed, proliferation anomalies. Ultrastructural studies of plants showed changes in cell membranes, as well as in the main cytoplasmic organelles. The revealed structural changes are assumed to contribute to a slowdown in the ontogenetic development of plants and a decrease in their morphometric parameters under anthropogenic pollution. No significant ultrastructure changes were observed in the roots compared with the leaves, which indicates their high adaptive potential.

The results of biogeochemical and bioindication studies on the resistance of natural populations of macrophyte plant-cattail (Typha australis Schum. & Thonn) on the coast of the Taganrog Bay of the Sea of Azov and the sea edge of the Don River delta with regard to local pollution zones are presented. Plant resistance has been assessed through manifestation of their protective functions in relation to heavy metals. An excess in the lithospheric Clarkes and MPC in Zn, Cd and Pb in Fluvisols has been found. The total index of soil pollution (Zc) has made it possible to identify areas with different categories of contamination within the study area exposed to human impact. High mobility of Zn, Cd, Pb, Cr and Ni in Fluvisols has been revealed, which is confirmed by the significant bioavailability of Zn, Cr and Cd that are accumulated in the macrophyte plant tissues. The absorption of heavy metals by cattail plants is allowed for both the soil and the water of the nearby reservoir, where aquatic systems are a kind of "biological filter" contributing to water purification from pollutants. The impact of the environmental stress factor has been found to be manifested not only in the features of heavy metal accumulation and distribution in plant tissues, but also at the morphological and anatomical level according to the type of prolification. Changes in the cell membranes as well as in main cytoplasmic organelles (mitochondria, plastids, pyroxis, etc.) of the root and leaf cells have been identified, the most significant changes in the ultrastructure being noted in the tissues of leaf chlorenchyma. It is assumed that the identified structural changes contribute to slowing down of the ontogenetic development of plants and reduction in their morphometric parameters when exposed to anthropogenic pollution. Therefore, cattails can be effectively used as biological indicators while determining environmental pressures.

Zinc based nanoparticles (NPs) have a great importance among the metal-based NPs and widely produced after SiO2 and TiO2. The rapid growth of ZnO NPs production and its abundant uses in many industries, and increasing release into an environment from both intentional and unintentional sources, create risks to human health. The recent finding of ZnO NPs application indicates positive and negative effects on plant growth. However, studies exploring the effect of ZnO NPs on the internal organelles of plants and their correlation with the function of photosynthesis are a few. The spring barley (Hordeum sativum L.) is one of the most important staples food crop and is identified as an efficient potentially toxic elements accumulator with phytoremediation potential. Thereby, the present work aimed to investigate the toxic effects of ZnO NPs on physiological and anatomical indices of H. sativum growth grown in a hydroponic condition as it allows to simplify model, where the parameters of plant growth can be easily controlled. Thus, the commercial-grade ZnO NPs (particle size 30-50 nm) was used with the scheme; control (0 ppm), low (300 ppm ZnO NPs), and high (2000 ppm ZnO NPs) the dose of NPs. The low and high levels of ZnO NPs were selected with consideration for the existing levels of Zn in the polluted soils. The results showed ZnO NPs affected the photosynthetic efficiency of H. sativum plants by affecting chlorophyll fluorescence emission, deformation in stomatal and trichomes morphology, damaged cellular organizations, i.e., irregularities in chloroplasts, disruption in grana and thylakoid organizations. Cytomorphometric quantification revealed that ZnO NPs decreased chloroplasts size 4 times in 2000 ppm and 1.5 times in 300 ppm ZnO NPs treated plants. The lower number of chloroplasts per cell were observed in ZnO NPs treated H. sativum leaf cells. The destructive methods of Zn elemental analysis showed 10.2 folds and 3.8 folds higher accumulation in 2000 ppm and 300 ppm ZnO NPs treated leaves than the control, respectively. Additionally, the presence of Zn content in H. sativum leaf tissue was also confirmed by the X-ray fluorescence spectroscopy elemental analysis. The high contents of Zn were visible in several spots in ZnO NPs treated leaf tissues. The accumulation of Zn content dissolute from ZnO NPs damaged the structural organization of the photosynthetic apparatus and reduced the photosynthetic activities. The modifications in anatomical indices were significantly correlated with physiological observations. The work presented here will help to increase the scientific understanding of the toxicity of ZnO NPs in plants and will widen the scope to tailor the nanomaterials to improve the effectiveness, smart and targeted delivery to avoid damages of most significant tissues of plants. This study was funded by the RFBR, project nos. 19-34-60041 and 18-29-25071, and the Ministry of Science and Higher Education of Russia, project no. 0852-2020-0029.

The aim of the present work was to investigate the toxic effects of zinc oxide nanoparticles (ZnO NPs, particle size &lt, 50 nm) on the physiological and anatomical indices of spring barley (Hordeum sativum L.). The results show that ZnO NPs inhibited H. sativum growth by affecting the chlorophyll fluorescence emissions and causing deformations of the stomatal and trichome morphology, alterations to the cellular organizations, including irregularities of the chloroplasts, and disruptions to the grana and thylakoid organizations. There was a lower number of chloroplasts per cell observed in the H. sativum leaf cells treated with ZnO NPs as compared to the non-treated plants. Cytomorphometric quantification revealed that ZnO NPs decreased the size of the chloroplast by 1.5 and 4 times in 300 and 2000 mg/L ZnO NP-treated plants, respectively. The elemental analysis showed higher Zn accumulation in the treated leaf tissues (3.8 and 10.18-fold with 300 and 2000 mg/L ZnO NPs, respectively) than the untreated. High contents of Zn were observed in several spots in ZnO NP-treated leaf tissues using X-ray fluorescence. Deviations in the anatomical indices were significantly correlated with physiological observations. The accumulation of Zn content in plant tissues that originated from ZnO NPs was shown to cause damage to the structural organization of the photosynthetic apparatus and reduced the photosynthetic activities.

The aim of this study is to investigate the adaptation of two species of cattail Typha australis Schum. and Thonn. and Typha laxmannii Lepech. based on analysis of the morphological and anatomical features of their vegetative and generative organs to soil pollution with potentially toxic elements (PTE) in the riparian zones of the sea edge of the Don River delta (Southern Russia). Both species of the cattail are able to accumulate high concentrations of Ni, Zn, Cd, Pb and can be used for phytoremediation of polluted territories. The pattern of PTE accumulation in hydrophytes has changed on polluted soils of coastal areas from roots/rhizomes &gt, inflorescences &gt, stems to roots/rhizomes &gt, stems &ge, inflorescences. The comparative morphological and anatomical analysis showed a statistically significant effect of the environmental stress factor by the type of proliferation in T. australis, and species T. laxmannii was visually in a depressed, deformed state with mass manifestations of hypogenesis. These deformations should be considered, on one hand, as adaptive, but on the other, as pathological changes in the structure of the spikes of the cattails. Light-optical and electron microscopic studies have shown that the degree and nature of ultrastructural changes in cattails at the same level of soil pollution are different and most expressed in the assimilation tissue of leaves. However, these changes were destructive for T. australis, but for T. laxmannii, these indicated a high level of adaptation to the prolonged technogenic impact of PTE.

Bioindication studies based on morphological parameters of Tyhpa australis showed that the influence of stress ecological factor is seen not only in peculiarities of accumulation and distribution of heavy metals in plant tissues, but also, at morphological-anatomical and ultrastructural level.