Assessment of heavy metals bioaccumulation in Silver Birch (Betula pendula Roth) from an AMD active, abandoned gold mine waste.

Acid mine drainage (AMD) is generally outlined as one of the largest environmental concerns, characterized by very low pH value of mine waste, heavy metals and high sulphate content. This extremely hostile environment reduces plant ability to develop and grow. Present study focuses on a silver birch (Betula pendula Roth), a pioneer species that grows on an extremely hostile gold mine waste, to investigate the bioaccumulation of rare metals (thallium (Tl) and indium (In)), as well as nine other more common heavy metals (bismuth (Bi), cadmium (Cd), cobalt (Co), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), silver (Ag) and zinc (Zn)), and to asses phytoextraction and phytostabilization potential of silver birch. Additionally, parameters determining AMD process and overall contamination (pH, electrical conductivity (EC), sulphates (SO42-), arsenic (As), iron (Fe), oxidation-reduction potential (ORP), turbidity, dissolved oxygen (DO), total dissolved solids (TDS), acidity, hardness, X-ray diffraction (XRD) and radioactivity) were determined in mine waste and drainage water samples. To assess the heavy metals bioaccumulation and mine waste status, statistical geochemical indices were determined: bioaccumulation factor (BCF), pollution load index (PLI), geochemical abundance index (GAI) and exposure index (EI). The results show that silver birch bioaccumulates the essential elements Cu, Ni, Mn and Zn, and the nonessential elements Tl (average BCF = 24.99), In (average BC = 23.01) and Pb (average BCF = 0.84). Investigated mine waste was enriched by Bi, Ag and Cd according to positive values of GAI index. Present research provides a novel insight into bioaccumulation of nonessential heavy metals in silver birches who grow on the extremely hostile mine waste, and they exhibit significant phytoremediation potential.

A Comparative Analysis of Radical Scavenging, Antifungal and Enzyme Inhibition Activity of 3'-8″-Biflavones and Their Monomeric Subunits.

Biflavonoids are dimeric forms of flavonoids that have recently gained importance as an effective new scaffold for drug discovery. In particular, 3'-8″-biflavones exhibit antiviral and antimicrobial activity and are promising molecules for the treatment of neurodegenerative and metabolic diseases as well as cancer therapies. In the present study, we directly compared 3'-8″-biflavones (amentoflavone, bilobetin, ginkgetin, isoginkgetin, and sciadopitysin) and their monomeric subunits (apigenin, genkwanin, and acacetin) and evaluated their radical scavenging activity (with DPPH), antifungal activity against mycotoxigenic fungi (Alternaria alternata, Aspergillus flavus, Aspergillus ochraceus, Fusarium graminearum, and Fusarium verticillioides), and inhibitory activity on enzymes (acetylcholinesterase, tyrosinase, α-amylase, and α-glucosidase). All the tested compounds showed weak radical scavenging activity, while antifungal activity strongly depended on the tested concentration and fungal species. Biflavonoids, especially ginkgetin and isoginkgetin, proved to be potent acetylcholinesterase inhibitors, whereas monomeric flavonoids showed higher tyrosinase inhibitory activity than the tested 3'-8″-biflavones. Amentoflavone proved to be a potent α-amylase and α-glucosidase inhibitor, and in general, 3'-8″-biflavones showed a stronger inhibitory potential on these enzymes than their monomeric subunits. Thus, we can conclude that 3'-8″-dimerization enhanced acetylcholinesterase, α-amylase, and α-glucosidase activities, but the activity also depends on the number of hydroxyl and methoxy groups in the structure of the compound.

Expression profile of the NCED/CCD genes in chickpea and lentil during abiotic stress reveals a positive correlation with increased plant tolerance.

Carotenoid cleavage dioxygenase (CCD) gene family is organized in two subfamilies: (i) 9-cis epoxycarotenoid dioxygenase (NCED) genes and (ii) CCD genes. NCED genes are essential for catalyzing the first step of the abscisic-acid (ABA) biosynthesis, while CCD genes produce precursors of the strigolactones hormone. The functional characterization of these gene subfamilies has not been yet performed in chickpea and lentil. Herein, were identified and systematically characterized two NCED and five CCD genes in the chickpea and two NCED and six CCD genes in lentil. After in silico sequence analysis and phylogeny, the expression profile of the NCED/CCD genes was determined by meta-analysis and real-time PCR in plants under different stress conditions. Sequence data revealed that NCED/CCD genes are highly conserved between chickpea and lentil. This conservation was observed both at gene and protein sequence levels and phylogenetic relationships. Analysis of the promoter sequences revealed that all NCED/CCD genes have a considerable number of cis-regulatory elements responsive to biotic and abiotic stress. Protein sequence analysis evidenced that NCED/CCD genes share several conserved motifs and that they have a highly interconnected interaction network. Furthermore, the three-dimensional structure of these proteins was determined and indicated that some proteins have structures with considerable similarity. The meta-analysis revealed that NCED/CCD genes are dynamically modulated in different organs and under different stress conditions, but they have a positive correlation with plant tolerance. In accordance, real-time PCR data showed that both NCED and CCD genes are differentially modulated in plants under drought stress. In particular, CaNCED2, CaCCD5, LcNCED2, LcCCD1, and LcCCD2 genes have a positive correlation with improved plant tolerance to drought stress. Therefore, this study presented a detailed characterization of the chickpea and lentil NCED/CCD genes and provided new insights to improve abiotic stress tolerance in these two important crops.

Exploring the crop epigenome: a comparison of DNA methylation profiling techniques.

Epigenetic modifications play a vital role in the preservation of genome integrity and in the regulation of gene expression. DNA methylation, one of the key mechanisms of epigenetic control, impacts growth, development, stress response and adaptability of all organisms, including plants. The detection of DNA methylation marks is crucial for understanding the mechanisms underlying these processes and for developing strategies to improve productivity and stress resistance of crop plants. There are different methods for detecting plant DNA methylation, such as bisulfite sequencing, methylation-sensitive amplified polymorphism, genome-wide DNA methylation analysis, methylated DNA immunoprecipitation sequencing, reduced representation bisulfite sequencing, MS and immuno-based techniques. These profiling approaches vary in many aspects, including DNA input, resolution, genomic region coverage, and bioinformatics analysis. Selecting an appropriate methylation screening approach requires an understanding of all these techniques. This review provides an overview of DNA methylation profiling methods in crop plants, along with comparisons of the efficacy of these techniques between model and crop plants. The strengths and limitations of each methodological approach are outlined, and the importance of considering both technical and biological factors are highlighted. Additionally, methods for modulating DNA methylation in model and crop species are presented. Overall, this review will assist scientists in making informed decisions when selecting an appropriate DNA methylation profiling method.

Plants strike back: Plant volatiles and their role in indirect defence against aphids.

As sessile organisms, plants have evolved different strategies to defend themselves against various biotic stressors. An important aspect of the complex response of plants to biotic stress is the emission of volatile compounds (VOCs), which are involved in direct and indirect plant defence mechanisms. Indirect plant defences include a range of plant traits that mediate defence against herbivores and play an important ecological role by not only utilising plants' own capabilities, but also signalling and attracting natural enemies of herbivores. Often the combination of volatiles emitted is specific to herbivores; they are consequently recognised by parasites and other predators, providing a clear link between the volatile signature and the prey. In this review, we focus on indirect plant defence and summarise current knowledge and perspectives on relationships between plants, aphids and parasitic wasps.

Interplay of plastic pollution with algae and plants: hidden danger or a blessing?

In the era of plastic pollution, plants have been discarded as a system that is not affected by micro and nanoplastics, but contrary to beliefs that plants cannot absorb plastic particles, recent research proved otherwise. The presented review gives insight into known aspects of plants' interplay with plastics and how plants' ability to absorb plastic particles can be utilized to remove plastics from water and soil systems. Microplastics usually cannot be absorbed by plant root systems due to their size, but some reports indicate they might enter plant tissues through stomata. On the other hand, nanoparticles can enter plant root systems, and reports of their transport via xylem to upper plant parts have been recorded. Bioaccumulation of nanoplastics in upper plant parts is still not confirmed. The prospects of using biosystems for the remediation of soils contaminated with plastics are still unknown. However, algae could be used to degrade plastic particles in water systems through enzyme facilitated degradation processes. Considering the amount of plastic pollution, especially in the oceans, further research is necessary on the utilization of algae in plastic degradation. Special attention should be given to the research concerning utilization of algae with restricted algal growth, ensuring that a different problem is not induced, "sea blooming", during the degradation of plastics.

Thinking for the future: Phytoextraction of cadmium using primed plants for sustainable soil clean-up.

Cadmium (Cd) soil contamination is a global problem for food security due to its ubiquity, toxicity at low levels, persistence, and bioaccumulation in living organisms. Humans' intake of heavy metals is usually due to direct contact with contaminated soil, through the food chain (Cd accumulation in crops and edible plants) or through drinking water in cases of coupled groundwater-surface water systems. Phytoextraction is one of the eco-friendly, sustainable solutions that can be used as a method for soil clean-up with the possibility of re-use of extracted metals through phytomining. Phytoextraction is often limited by the tolerance level of hyperaccumulating plants and the restriction of their growth. Mechanisms of hyperaccumulation of heavy metals in tolerant species have been studied, but there are almost no data on mechanisms of further improvement of the accumulation capacity of such plants. Priming can influence plant stress tolerance by the initiation of mild stress cues resulting in acclimation of the plant. The potential of plant priming in abiotic stress tolerance has been extensively investigated using different types of molecules that are supplemented exogenously to plant organs (roots, leaves, etc.), resulting in enhanced tolerance of abiotic stress. This review focuses on mechanisms of enhancement of plant stress tolerance in hyperaccumulating plants for their exploitation in phytoextraction processes.

Biflavonoids: Important Contributions to the Health Benefits of Ginkgo (Ginkgo biloba L.).

Ginkgo (Ginkgo biloba L.) is one of the most distinctive plants, characterized by excellent resistance to various environmental conditions. It is used as an ornamental plant and is recognized as a medicinal plant in both traditional and Western medicine. Its bioactive potential is associated with the presence of flavonoids and terpene trilactones, but many other compounds may also have synergistic effects. Flavonoid dimers-biflavonoids-are important constituents of ginkgophytopharmaceuticals. Currently, the presence of 13 biflavonoids has been reported in ginkgo, of which amentoflavone, bilobetin, sciadopitysin, ginkgetin and isoginkgetin are the most common. Their role in plants remains unknown, but their bioactivity and potential role in the management of human health are better investigated. In this review, we have provided an overview of the chemistry, diversity and biological factors that influence the presence of biflavonoids in ginkgo, as well as their bioactive and health-related properties. We have focused on their antioxidant, anticancer, antiviral, antibacterial, antifungal and anti-inflammatory activities as well as their potential role in the treatment of cardiovascular, metabolic and neurodegenerative diseases. We also highlighted their potential toxicity and pointed out further research directions.

Influence of Climate-Related Environmental Stresses on Economically Important Essential Oils of Mediterranean Salvia sp.

Salvia L. is the largest genus in the family Lamiaceae, with about 1,000 species and a nearly cosmopolitan distribution. Salvia species are used in both traditional and conventional medicines, and other numerous industries, such as spices and perfumes. The number of papers dealing with Salvia exceeds 12,000 and mostly investigates their chemical composition and bioactive properties. A smaller proportion of papers however consider environmental factors, mostly on the effects of microclimate conditions on its geographic distribution along an altitudinal or longitudinal gradient, and very few studies can be found on the effects of emerging stressors on the commercial production of sages of medicinal and economical importance. Here, we summarize available data on the essential oil composition of three economically important sages from the Mediterranean area, that is, Salvia officinalis, Salvia officinalis subsp. lavandulifolia, and Salvia fruticosa, and the effects of climate-related environmental stressors on their chemical profiles. Environmental stress factors, such as an increase in soil salinity and aridity, and changes in annual average temperatures, are going to impose a serious risk on the commercial production of sage essential oils, which are commercially produced in many European countries. This review highlights the already confirmed effects of these stressors on three selected Salvia species and consequently the importance of mitigating the effects of climate change on the commercial production of these essential oils.

Exploring New Sources of Bioactive Phenolic Compounds from Western Balkan Mountains.

This study presents the first report on phenolic composition and bioactivity of ethanolic extracts of three plant species that grow in the western Balkan mountains and are used in traditional folk medicine: Valeriana montana, Salix retusa, and Campanula hercegovina. Phenolics were extracted from different aerial plant parts using 80% ethanol to assess the possibility of sustainable use of these plants as a source of bioactive compounds without disruption to the roots (for V. montana) or destruction of whole habitats (for S. retusa and C. hercegovina). The ethanolic extract of V. montana flower contained noticeable levels of apigenin and quercetin. The branches and bark of S. retusa were significantly rich in catechin, while rutin was the major phenolic found in the leaf extract of C. hercegovina. Furthermore, the flower extract of V. montana revealed the best antioxidant activity, which was comparable to 4-hydroxybenzoic acid and quercetin. Considering antimicrobial activity, the leaf extracts of V. montana and C. hercegovina demonstrated potent activity against all microbes tested, while the extracts of S. retusa were moderately effective. The presented results emphasize the potential of these plants as novel sources of bioactive compounds.

Deciphering the Epigenetic Alphabet Involved in Transgenerational Stress Memory in Crops.

Although epigenetic modifications have been intensely investigated over the last decade due to their role in crop adaptation to rapid climate change, it is unclear which epigenetic changes are heritable and therefore transmitted to their progeny. The identification of epigenetic marks that are transmitted to the next generations is of primary importance for their use in breeding and for the development of new cultivars with a broad-spectrum of tolerance/resistance to abiotic and biotic stresses. In this review, we discuss general aspects of plant responses to environmental stresses and provide an overview of recent findings on the role of transgenerational epigenetic modifications in crops. In addition, we take the opportunity to describe the aims of EPI-CATCH, an international COST action consortium composed by researchers from 28 countries. The aim of this COST action launched in 2020 is: (1) to define standardized pipelines and methods used in the study of epigenetic mechanisms in plants, (2) update, share, and exchange findings in epigenetic responses to environmental stresses in plants, (3) develop new concepts and frontiers in plant epigenetics and epigenomics, (4) enhance dissemination, communication, and transfer of knowledge in plant epigenetics and epigenomics.

Influence of Extraction Solvent on the Phenolic Profile and Bioactivity of Two Achillea Species.

The phenolic composition, as well as the antioxidant and antimicrobial activities of two poorly investigated Achillea species, Achillea lingulata Waldst. and the endemic Achillea abrotanoides Vis., were studied. To obtain a more detailed phytochemical profile, four solvents with different polarities were used for the preparation of the plant extracts whose phenolic composition was analyzed using UHPLC-MS/MS (ultra-high performance liquid chromatography-tandem mass spectrometry). The results indicate that both of the investigated Achillea species are very rich in both phenolic acids and flavonoids, but that their profiles differ significantly. Chloroform extracts from both species had the highest yields and were the most chemically versatile. The majority of the examined extracts showed antimicrobial activity, while ethanolic extracts from both species were potent against all tested microorganisms. Furthermore, the antioxidant activity of the extracts was evaluated. It was found that the ethanolic extracts possessed the strongest antioxidant activities, although these extracts did not contain the highest amounts of detected phenolic compounds. In addition, several representatives of phenolic compounds were also assayed for these biological activities. Results suggest that ethanol is a sufficient solvent for the isolation of biologically active compounds from both Achillea species. Moreover, it was shown that the flavonoids naringenin and morin are mainly responsible for these antimicrobial activities, while caffeic, salicylic, chlorogenic, p-coumaric, p-hydroxybenzoic, and rosmarinic acid are responsible for the antioxidant activities of the Achillea extracts.

The Role of Polyphenols in Abiotic Stress Response: The Influence of Molecular Structure.

Abiotic stressors such as extreme temperatures, drought, flood, light, salt, and heavy metals alter biological diversity and crop production worldwide. Therefore, it is important to know the mechanisms by which plants cope with stress conditions. Polyphenols, which are the largest group of plant-specialized metabolites, are generally recognized as molecules involved in stress protection in plants. This diverse group of metabolites contains various structures, from simple forms consisting of one aromatic ring to more complex ones consisting of large number of polymerized molecules. Consequently, all these molecules, depending on their structure, may show different roles in plant growth, development, and stress protection. In the present review, we aimed to summarize data on how different polyphenol structures influence their biological activity and their roles in abiotic stress responses. We focused our review on phenolic acids, flavonoids, stilbenoids, and lignans.

Use of seed priming to improve Cd accumulation and tolerance in Silene sendtneri, novel Cd hyper-accumulator.

Changes in the environment as a result of industrialisation and urbanisation impact negatively on plant growth and crop production. Cadmium (Cd) is one of the most dangerous metals that enters the food chain, with toxic effects on plants and human health. This study evaluated the potential of Silene sendtneri as a novel hyperaccumulator and the role of seed priming in tolerance and accumulation rate of Cd. The effect of different priming agents on germination performance, root growth, seedling development, metal uptake and accumulation, antioxidant defences including enzymatic and non-enzymatic antioxidants has been assessed. Seed priming using silicic acid, proline alone or in combination with salicylic acid- enhanced germination, seedling development, and root growth under Cd stress. The same priming treatments induced an increase of water content in shoots and roots when plants were exposed to Cd. The enzymatic antioxidant response was specific for the priming agent used. An increase in ferulic acid and rutin in shoots was related to the increase of Cd concentration in the medium. The concentration of malic and oxalic acid increased significantly in shoots of plants grown on high Cd concentrations compared to low Cd concentrations. Silene sendtneri can accumulate significant levels of Cd with enhanced accumulation rate and tolerance when seeds are primed. The best results are obtained by seed priming using 1% silicic acid, proline and salicylic acid.

Phenolic compounds and bioactive properties of Verbascum glabratum subsp. bosnense (K. Malý) Murb., an endemic plant species.

Detailed analysis of phenolic composition and antioxidant and antimicrobial activities of Verbascum glabratum subsp. bosnense (K. Malý) Murb., an endemic species of southeastern Dinaric Alps was performed for the first time. The phenolic composition measured via UHPLC-MS/MS of four extract with different polarity suggested this plant species is very rich in both phenolic acids and flavonoids. Ethanol extract was chemically the most versatile containing 12 compounds with quercitrin and rosmarinic acid as the majors, while water extracts were rich in 4-hydroxybenzoic acid, salicylic acid, morin, and apigenin. All extracts showed high antioxidant potential measured spectrophotometrically with IC50 values ranging 0.139 - 0.021 mg/mL. Antimicrobial testing using agar diffusion test showed that ethanol extract was the most potent against all tested organisms. Also, these activities are correlated with the content of phenolic compounds, which suggest they are active ingredients of the extracts.

The effect of hydro and proline seed priming on growth, proline and sugar content, and antioxidant activity of maize under cadmium stress.

We tested the effect of seed hydro- and proline-priming on cadmium (Cd) tolerance in maize plants. Soil supplemented with two concentrations of cadmium was used for the investigation. Cadmium content, fresh and dry mass, shoot length, leaf length and width, chlorophyll, proline, sugar and protein content, and antioxidant potential in 4-week-old plants were analysed. Cadmium content in soil and maize shoots was determined by flame atomic absorption spectrometry. Accumulation of Cd was observed for all plants, and highest Cd concentration was recorded in seedlings grown from proline-primed seeds with no visual signs of Cd toxicity. In proline-primed plants, increase in leaf length, photosynthetic pigments, and sugar and proline content as well as changes in antioxidant enzyme activities was recorded. Results obtained in this study suggest that proline-priming of maize seeds induces activation of defensive mechanisms, such as proline and sugar synthesis, which in return alleviates Cd toxicity on maize growth with increased Cd accumulation comparing to control plants.

Evaluation of phenolic profile, enzyme inhibitory and antimicrobial activities of Nigella sativa L. seed extracts.

Black cumin (Nigella sativa L. [N.sativa]) seed extracts demonstrated numerous beneficial biological effects including, among others, antidiabetic, anticancer, immunomodulatory, antimicrobial, anti-inflammatory, antihypertensive, and antioxidant activity. To better understand the phytochemical composition of N. sativa seeds, methanol seed extracts were analyzed for phenolic acid and flavonoid content. Furthermore, we tested N. sativa methanol, n-hexane, and aqueous seed extracts for their inhibitory activity against butyrylcholinesterase (BChE) and catalase (CAT) as well as for antimicrobial activity against several bacterial and a yeast strains. The phenolic content of N. sativa was analyzed using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The inhibition of BChE was assessed by modified Ellman's method, and the inhibition of CAT was determined by monitoring hydrogen peroxide consumption. The extracts were tested against Bacillus subtilis, Staphylococcus aureus, Salmonella enterica, and Escherichia coli using the agar diffusion method. The UHPLC-MS/MS method allowed the identification and quantification of 23 phenolic compounds within 15 minutes. The major components found in N. sativa seed extract were sinapinic acid (7.22 ± 0.73 µg/mg) as a phenolic acid and kaempferol (11.74 ± 0.92 µg/mg) as a flavonoid. All extracts showed inhibitory activity against BChE, with methanol seed extract demonstrating the highest inhibitory activity (inhibitory concentration 50% [IC50] 79.11 ± 6.06 µg/ml). The methanol seed extract also showed strong inhibitory activity against CAT with an IC50 value of 6.61 ± 0.27 µg/ml. Finally, the methanol extract exhibited considerable inhibitory activity against the tested microbial strains. Overall, this is the first study to investigate the ability of black cumin seed extracts to inhibit CAT. Our results indicate that N. sativa seed can be considered as an effective inhibitor of CAT activity.

Variation in Phenolic Composition of Knautia arvensis in Correlation with Geographic Area and Plant Organ.

Knautia arvensis (family Dipsacaceae) is usually found in grasslands of Europe, but can also be found in some parts of Africa and Asia, usually in dry meadows, pastures, dry hills, and open woods. The chemical composition of this species is relatively unknown. The aim of this study was to give a phenolic profile of this plant, and to show how its phenolic composition varies depending upon plant organ and geographic origin. The chemical analysis included quantification of free phenolics soluble in methanol, esters and glycosides, and phenolics that are insoluble in methanol. Fourteen different phenolic acids and eight flavonoids were quantified in total. According to this study, the chemical composition of individual plant parts can differ tremendously within one - population, which does not have to be in correspondence with chemical variability between populations. As shown in this study, the variation in chemical composition between plant parts can exceed that between different populations (from different climates, altitudes, with different environmental factors), which implies that microhabitat conditions can greatly affect the composition of some plant parts, which was shown also after PCA and HCA analysis.