Efficiency of the alpha-hairpinin SmAMP-X gene promoter from Stellaria media plant depends on selection of transgenic approach.

The antimicrobial activity of the alpha-HAIRPININ ANTIMICROBIAL PEPTIDE X (SmAMP-X gene, GenBank acc. No. HG423454.1) from Stellaria media plant has been shown in vitro. Here, we isolated the SmAMP-X gene promoter and found two genomic sequences for the promoter (designated pro-SmAMP-X and pro-SmAMP-X-Ψ2) with 83% identity in their core and proximal regions. We found that the abilities of these promoters to express the uidA reporter and the nptII selectable marker differ according to the structural organization of T-DNA in the binary vector used for plant transformation. Analysis of Agrobacterium-infiltrated Nicotiana benthamiana leaves, transgenic Arabidopsis thaliana lines, and transgenic Solanum tuberosum plants revealed that both promoters in the pCambia1381Z and pCambia2301 binary vectors generate 42-100% of the ß-glucuronidase (GUS) activity generated by the CaMV35S promoter. According to 5'-RACE (rapid amplification of cDNA ends) analysis, both plant promoters are influenced by the CaMV35S enhancer used to express selectable markers in the T-DNA region of pCambia1381Z and pCambia2301. The exclusion of CaMV35S enhancer from the T-DNA region significantly reduces the efficiency of pro-SmAMP-X-Ψ2 promoter for GUS production. Both promoters in the pCambia2300 vector without CaMV35S enhancer in the T-DNA region weakly express the nptII selectable marker in different tissues of transgenic N. tabacum plants and enable selection of transgenic cells in media with a high concentration of kanamycin. Overall, promoter sequences must be functionally validated in binary vectors lacking CaMV35S enhancer.

Molecular networking-guided isolation strategy of a new C-glycosyl flavone rotamer from Stellaria alsine and evaluation of anti-inflammatory and antioxidant activities.

INTRODUCTION: Stellaria alsine has traditionally been used as both a famine relief food and an alternative medicine in East Asia. Modern pharmacological studies have revealed that S. alsine has various biological effects such as anticancer, anti-hepatoma, anti-inflammatory, and antioxidative effects. However, the anti-inflammatory properties of chemical constituents derived from this plant have not been studied well. OBJECTIVES: To identify potential therapeutic candidate for treating inflammatory diseases such as inflammatory bowel disease (IBD). METHODS: The distribution of chemical compounds was investigated by Global Natural Product Social (GNPS)-based molecular networking (MN) analysis using UPLC-Orbitrap tandem mass spectrometry. The anti-inflammatory and antioxidative effects of S. alsine extracts and fractions were evaluated by measuring interleukin (IL)-8 and reactive oxygen species (ROS) productions. RESULTS: The active EA layer of S. alsine showed the highest percentage of major compounds by feature-based molecular networking. The top candidate structures of EA fraction were rapidly annotated as flavone C- or O-glycosides via an advanced analysis tool, Network Annotation Propagation (NAP). With the GNPS molecular networking-guided isolation strategy, a new C-glycosyl flavone rotamer (1) was isolated. The structures of the major (1a) and minor (1b) rotational isomers were determined by extensive NMR analysis and MS/MS fragmentation. Finally, the anti-inflammatory activity of 1 was predicted by molecular docking simulations with IL-8 protein. CONCLUSION: These results suggested that the compound 1 is a potential therapeutic candidate for inflammatory bowel disease (IBD).

Complete genome sequence of Stellaria aquatica virus B, a novel polerovirus that infects Stellaria aquatica.

The complete genome sequence of Stellaria aquatica virus B (StAVB), a new member of the genus Polerovirus that infects Stellaria aquatica, was determined using high-throughput RNA sequencing with confirmation by Sanger sequencing. The complete StAVB genome (GenBank accession no. OP389993) is 5,900 nucleotide (nt) long with seven open reading frames (ORF0-5 and ORF3a) that encode putative proteins (P0-P5 and P3a) in a similar configuration to that of other typical poleroviruses. Pairwise sequence comparisons with other poleroviruses showed 38-50% nt sequence identity in the complete genome and 13-24%, 36-45%, 7-68%, and 6-50% amino acid sequence identity in (aa), for the P0, P1-2, P3, and P4 protein, respectively. These data, together with the results of phylogenetic analysis, indicate that StAVB should be classified as a new member of the genus Polerovirus, family Solemoviridae.

The complete genome sequence of Stellaria aquatica virus A, a new member of the genus Alphacarmovirus, family Tombusviridae.

A new member of the genus Alphacarmovirus was detected in Stellaria aquatica using high-throughput RNA sequencing analysis. The complete genome sequence of this new virus isolate, tentatively named "Stellaria aquatica virus A" (StAV-A), comprises 4,017 nucleotides with five predicted open reading frames (ORFs) and has a typical alphacarmovirus genome organization. Pairwise comparison of StAV-A with selected members of family Tombusviridae showed 44-58%, 32-64%, and 19-49% sequence identity for the overall nucleotide sequence, polymerase, and coat protein, respectively. Phylogenetic analysis of polymerase sequences places StAV-A alongside other members of the genus Alphacarmovirus in the family Tombusviridae.

Phytochemical analysis and gastroprotective effect of Stellaria media (L.) Vill. methanolic extract on piroxicam-induced gastric ulcer in Wistar rats.

Stellaria media L. has traditionally been used to treat inflammatory and gastrointestinal ailments. This study aimed to phytochemically characterize the S. media extract and explore its anti-ulcer efficacy against piroxicam-induced stomach lesions in Wistar rats. Phytochemical analysis was performed and antioxidant capacity of extract was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. In vivo, piroxicam (30mg/kg) was administered to induce gastric ulceration. Gastro protective effect of S. media extract was observed at 150, 300 and 450mg/kg, respectively. While omeprazole (20mg/kg) was used as a conventional anti-ulcer drug. After oral treatment for 14 days, stomach acidic secretions, ulcerogenic indices, hematological markers and oxidative stress parameters were assessed along with histological examination. The existence of polyphenol contents in S. media extract was confirmed in correlation to a marked DPPH inhibition (IC50 27.94µg/mL). S. media extract resulted in a dose-dependent elevation in gastric pH while a decrease in acid volume, acidity and ulceration. Also, S. media extract administration restored the impaired hematological markers (RBCs, Hb, WBCs and PLTs) and decreased oxidative stress by reducing oxidants (TOS and MDA) while raising antioxidants (TAC and CAT). Furthermore, gastric histological results corroborated the aforementioned findings. Conclusively, S. media could provide a promising protective effect against drug-induced gastric ulceration.

Evolution of apetaly in the cosmopolitan genus Stellaria.

PREMISE: Apetaly is widespread across distantly related lineages of flowering plants and is associated with abiotic (or self-) pollination. It is particularly prevalent in the carnation family, and the cosmopolitan genus Stellaria contains many lineages that are hypothesized to have lost petals from showy petalous ancestors. But the pollination biology of apetalous species of Stellaria remains unclear. METHODS: Using a substantial species-level sampling (~92% of known taxonomic diversity), we describe the pattern of petal evolution within Stellaria using ancestral character state reconstructions. To help shed light on the reproductive biology of apetalous Stellaria, we conducted a field experiment at an alpine tundra site in the southern Rocky Mountains to test whether an apetalous species (S. irrigua) exhibits higher levels of selfing than a sympatric, showy petalous congener (S. longipes). RESULTS: Analyses indicated that the ancestor of Stellaria was likely showy petalous and that repeated, parallel reductions of petals occurred in clades across much of the world, with uncommon reversal back to showy petals. Field experiments supported high rates of selfing in the apetalous species and high rates of outcrossing in the petalous species. CONCLUSIONS: Petal loss is rampant across major clades of Stellaria and is potentially linked with self-pollination worldwide. Self-pollination occurs within the buds in S. irrigua, and high propensities for this and other forms of selfing known in many other taxa of arctic-alpine habitats may reflect erratic availability of pollinators.

Effects of mutual intercropping on the cadmium accumulation in accumulator plants Stellaria media, Malachium aquaticum, and Galium aparine.

Intercropping affects heavy-metal uptake in plants. In this study, three cadmium (Cd)-accumulator species (Stellaria media, Malachium aquaticum, and Galium aparine) were intercropped together in Cd-contaminated soil to study the effects of intercropping on co-remediation. Mutual intercropping significantly increased the biomasses of S. media, M. aquaticum, and G. aparine compared with their respective monocultures. The photosynthetic pigment contents of three species were not significantly affected by mutual intercropping. Mutual intercropping did not increase the Cd contents in roots and shoots of G. aparine, but it increased the Cd contents in roots of S. media and M. aquaticum. It also decreased the Cd contents in shoots of S. media and M. aquaticum. Only G. aparine intercropped with M. aquaticum and three-species intercropping increased Cd-accumulation levels in whole plants of each species. Only S. media intercropped with M. aquaticum and three-species intercropping increased the Cd accumulation at the whole plant level in every plant in a single pot, with S. media intercropped with M. aquaticum showing the greatest increase. Therefore, S. media intercropped with M. aquaticum and three-species intercropping may improve the efficiency of phytoremediation of Cd-contaminated soil, with S. media intercropped with M. aquaticum representing the best combination.

Novel strong promoter of antimicrobial peptides gene pro-SmAMP2 from chickweed (Stellaria media).

BACKGROUND: In a previous study we found that in chickweed the expression level of the pro-SmAMP2 gene was comparable or even higher to that of the ß-actin gene. This high level of the gene expression has attracted our attention as an opportunity for the identification of novel strong promoters of plant origin, which could find its application in plant biotechnology. Therefore, in the present study we focused on the nucleotide sequence identification and the functional characteristics of the pro-SmAMP2 promoter in transgenic plants. RESULTS: In chickweed (Stellaria media), a 2120 bp promoter region of the pro-SmAMP2 gene encoding antifungal peptides was sequenced. Six 5'-deletion variants -2120, -1504, -1149, -822, -455, and -290 bp of pro-SmAMP2 gene promoter were fused with the coding region of the reporter gene gusA in the plant expression vector pCambia1381Z. Independent transgenic plants of tobacco Nicotiana tabacum were obtained with each genetic structure. GUS protein activity assay in extracts from transgenic plants showed that all deletion variants of the promoter, except -290 bp, expressed the gusA gene. In most transgenic plants, the GUS activity level was comparable or higher than in plants with the viral promoter CaMV 35S. GUS activity remains high in progenies and its level correlates positively with the amount of gusA gene mRNA in T3 homozygous plants. The activity of the рro-SmAMP2 promoter was detected in all organs of the transgenic plants studied, during meiosis and in pollen as well. CONCLUSION: Our results show that the рro-SmAMP2 promoter can be used for target genes expression control in transgenic plants.

[Expression of plant antimicrobial peptide pro-SmAMP2 gene increases resistance of transgenic potato plants to Alternaria and Fusarium pathogens].

The chickweed (Stellaria media L.) pro-SmAMP2 gene encodes the hevein-like peptides that have in vitro antimicrobial activity against certain harmful microorganisms. These peptides play an important role in protecting the chickweed plants from infection, and the pro-SmAMP2 gene was previously used to protect transgenic tobacco and Arabidopsis plants from phytopathogens. In this study, the pro-SmAMP2 gene under control of viral CaMV35S promoter or under control of its own pro-SmAMP2 promoter was transformed into cultivated potato plants of two cultivars, differing in the resistance to Alternaria: Yubiley Zhukova (resistant) and Skoroplodny (susceptible). With the help of quantitative real-time PCR, it was demonstrated that transgenic potato plants expressed the pro-SmAMP2 gene under control of both promoters at the level comparable to or exceeding the level of the potato actin gene. Assessment of the immune status of the transformants demonstrated that expression of antimicrobial peptide pro-SmAMP2 gene was able to increase the resistance to a complex of Alternaria sp. and Fusarium sp. phytopathogens only in potato plants of the Yubiley Zhukova cultivar. The possible role of the pro-SmAMP2 products in protecting potatoes from Alternaria sp. and Fusarium sp. is discussed.

Novel antifungal α-hairpinin peptide from Stellaria media seeds: structure, biosynthesis, gene structure and evolution.

Plant defense against disease is a complex multistage system involving initial recognition of the invading pathogen, signal transduction and activation of specialized genes. An important role in pathogen deterrence belongs to so-called plant defense peptides, small polypeptide molecules that present antimicrobial properties. Using multidimensional liquid chromatography, we isolated a novel antifungal peptide named Sm-AMP-X (33 residues) from the common chickweed (Stellaria media) seeds. The peptide sequence shows no homology to any previously described proteins. The peculiar cysteine arrangement (C(1)X3C(2)XnC(3)X3C(4)), however, allocates Sm-AMP-X to the recently acknowledged α-hairpinin family of plant defense peptides that share the helix-loop-helix fold stabilized by two disulfide bridges C(1)-C(4) and C(2)-C(3). Sm-AMP-X exhibits high broad-spectrum activity against fungal phytopathogens. We further showed that the N- and C-terminal "tail" regions of the peptide are important for both its structure and activity. The truncated variants Sm-AMP-X1 with both disulfide bonds preserved and Sm-AMP-X2 with only the internal S-S-bond left were progressively less active against fungi and presented largely disordered structure as opposed to the predominantly helical conformation of the full-length antifungal peptide. cDNA and gene cloning revealed that Sm-AMP-X is processed from a unique multimodular precursor protein that contains as many as 12 tandem repeats of α-hairpinin-like peptides. Structure of the sm-amp-x gene and two related pseudogenes sm-amp-x-ψ1 and sm-amp-x-ψ2 allows tracing the evolutionary scenario that led to generation of such a sophisticated precursor protein. Sm-AMP-X is a new promising candidate for engineering disease resistance in plants.

[Effect of drought stress on growth and physiological-biochemical characteristics of Stellaria dichotoma].

A pot experiment was conducted to study effect of drought stress on leaf physiological characteristics and growth of one year old Stellaria dichotoma seedlings. The result showed that plant height and shoot dry weight significantly decreased with decrease in soil water content; however, root length and root dry weight increased at light drought stress and decreased at severe drought stress. The result also showed that with the decrease of soil water content, proline content in S. dichotoma leaves decreased then increase, while solube protein content decreased. Activities of SOD and POD in S. dichotoma leaves significantly decreased as soil water content decreased, while activity of CAT significantly decreased at severe drought stress. Membrane permeability in S. dichotoma leaves increased, while MDA content decreased then increased as soil water decreased. These results suggest that S. dichotoma had osmotic stress resistance ability and reactive oxygen scavenging capacity at light drought stress, which caused S. dichotoma growth was no inhibited at a certain extent drought stress.

Purification and characterization of a novel anti-HSV-2 protein with antiproliferative and peroxidase activities from Stellaria media.

A novel antiviral protein, designated as Stellarmedin A, was purified from Stellaria media (L.) Vill. (Caryophyllaceae) by using ammonium sulfate precipitation, cation-exchange chromatography system. Gel electrophoresis analysis showed that Stellarmedin A is a highly basic glycoprotein with a molecular weight of 35.1 kDa and an isoelectric point of ∼8.7. The N-terminal 14-amino acid sequence, MGNTGVLTGERNDR, is similar to those of other plant peroxidases. This protein inhibited herpes simplex virus type 2 (HSV-2) replication in vitro with an IC50 of 13.18 µg/ml and a therapeutic index exceeding 75.9. It was demonstrated that Stellarmedin A affects the initial stage of HSV-2 infection and is able to inhibit the proliferation of promyelocytic leukemia HL-60 and colon carcinoma LoVo cells with an IC50 of 9.09 and 12.32 µM, respectively. Moreover, Stellarmedin A has a peroxidase activity of 36.6 µmol/min/mg protein, when guaiacol was used as substrate. To our knowledge, this is the first report about an anti-HSV-2 protein with antiproliferative and peroxidase activities from S. media.

Target-site basis for resistance to acetolactate synthase inhibitor in Water chickweed (Myosoton aquaticum L.).

Water chickweed is a widespread and competitive winter annual or biennial weed of wheat in China. One Water chickweed population (HN02) resistant to several acetolactate synthase (ALS) inhibitors was found in Henan province of China. Whole-plant bioassays showed that HN02 was high resistance to tribenuron (292.05-flod). In vitro ALS assays revealed that resistance was due to reduced sensitivity of the ALS enzyme to tribenuron. The I50 value for HN02 was 85.53 times greater respectively than that of susceptible population (SD05). This altered ALS sensitivity in the resistant population was due to a mutation in the ALS gene resulting in a Pro197 to Ser substitution. Cross-resistance experiments indicated that HN02 exhibited various resistance patterns to pyrithiobac-sodium, florasulam and pyroxsulam, without resistance to imazethapyr. This is the first report of tribenuron-resistant Water chickweed in Henan province of China, target-site based resistance was established as being due to an insensitive form of ALS, resulting from a Pro to Ser substitution at amino acid position 197 in the ALS gene.

Evaluation of hepatoprotective activity of water-soluble polysaccharide fraction of Stellaria media L.

Therapy of rats with CCl4 hepatitis with Stellaria media L. water-soluble polysaccharide fraction in a dose of 100 mg/kg reduces serum activities of transaminases (ALT and AST), alkaline phosphatase, bilirubin, and the thymol test values. In the liver, the density of inflammatory infiltration of the organ parenchyma, total count of necrotic hepatocytes, fatty and protein degeneration are reducing. Hence, water-soluble polysaccharide fraction, isolated from the terrestrial part of Stellaria media L., is characterized by hepatoprotective activity.

Transformation of tobacco and Arabidopsis plants with Stellaria media genes encoding novel hevein-like peptides increases their resistance to fungal pathogens.

Two novel antifungal hevein-like peptides, SmAMP1.1a and SmAMP2.2a, were previously isolated from seeds of Stellaria media. It has been established that these peptides accumulate in this weed as a result of proteolysis of two propeptides, pro-SmAMP1 and pro-SmAMP2. The primary structure of these propeptides is unique; in addition to having a signal peptide and negatively charged C-terminus, each of these structures consists of two hevein-like peptides of different length separated by a space rather than a single peptide. In this work, we demonstrated that the expression of the pro-SmAMP1 and pro-SmAMP2 genes was tissue-specific and increased substantially under exposure to fungal infection. To elucidate whether S. media has any advantages in defending against phytopathogens due to its unusual structure of pro-SmAMP1 and pro-SmAMP2, on the basis of the pro-SmAMP1 gene, we created three genetic constructs. Arabidopsis and tobacco plants were subsequently transformed with these constructs. Transgenic plants bearing the full-length pro-SmAMP1 gene exhibited the best resistance to the phytopathogens Bipolaris sorokiniana and Thielaviopsis basicola. The resistance of S. media plants to phytopathogenic fungi was likely due to the fungal-inducible expression of pro-SmAMP1 and pro-SmAMP2 genes, and due to the specific features of the primary structure of the corresponding propeptides. As a result of the processing of these propeptides, two different antimicrobial peptides were released simultaneously. Based on our results, we conclude that the genes for antimicrobial peptides from S. media may be promising genetic tools for the improvement of plant resistance to fungal diseases.

Quality assessment and anti-obesity activity of Stellaria media (Linn.) Vill.

BACKGROUND: Obesity is recognized as a social problem, associated with serious health risks and increased mortality. Numerous trials have been conducted to find and develop new anti-obesity drugs through herbal sources to minimize side effects associated with the present anti-obesity drugs. The present study was designed to evaluate the quality control parameters, quantitative phytochemical analysis (total phenolic, total flavonoids and total saponin content), and the anti-obesity effect of lyophilized juice (LJ) of Stellaria media (Linn.) Vill. by employing in vitro and in vivo models. METHODS: In vitro studies were performed to evaluate the inhibitory activity of LJ on pancreatic amylase and lipase. The in vivo pancreatic lipase activity was evaluated by measurement of plasma triacylglycerol levels after oral administration of lipid emulsion to swiss albino mice. Furthermore, the anti-obesity effect of LJ was assessed at two doses, 400 mg/kg and 900 mg/kg body weight in mice fed a high-fat-diet with or without LJ for 6 weeks. RESULTS: The LJ inhibited pancreatic amylase and lipase activity in vitro and elevated plasma triacylglycerol level in mice. LJ suppressed the increase in body weight, retroperitoneal adipose tissue, liver weights and serum parameters viz., total cholesterol, total triglyceride, LDL-cholesterol level at the dose of 900 mg/kg body weight of the mice fed with high fat diet. The total phenolic, flavonoid and saponin contents were found to be 0.26 mg/g, 1.4 mg/g and 1.19 µg/g respectively of LJ. CONCLUSION: The anti-obesity effects of LJ in high-fat-diet fed mice may be partly mediated through delaying the intestinal absorption of dietary fat and carbohydrate by inhibiting digestive enzymes.

Anti-hepatitis B virus activity of chickweed [Stellaria media (L.) Vill.] extracts in HepG2.2.15 cells.

Stellaria media (Linn.) Villars is a traditional Chinese medicine that has been used for over 200 years, mainly for the treatment of dermatitis and other skin diseases. It has also been used as an anti-viral agent. All the fresh chickweed juice samples used in this study were prepared using macroporous resin and ultrafiltration technology. The anti-hepatitis B virus (HBV) activity of S. media was evaluated in vitro using the human HBV-transfected liver cell line HepG2.2.15. The concentrations of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) in HepG2.2.15 cell culture medium were determined by enzyme-linked immunosorbent assay (ELISA) after S. media-n (SM-n) treatment for 6 or 9 days. HBV DNA was quantified using transcription-mediated amplification and real-time polymerase chain reaction. In HepG2.2.15 cells, 30 µg/mL SM-3 effectively suppressed the secretion of HBsAg and HBeAg with inhibition rates of 27.92% and 25.35% after 6 days of treatment, respectively. Consistent with the reduction in HBV antigens, SM-3 also reduced the level of HBV DNA in a dose-dependent manner. The characterization and quantitation of the chemical composition of SM-3 showed the presence of flavonoid C-glycosides, polysaccharides, and protein, which exhibited diverse antiviral activities. In conclusion, our results demonstrate that SM-3 possesses potential anti-HBV activity in vitro. This is the first report demonstrating the anti-HBV effects of S. media, which is currently under early development as a potential anti-HBV drug candidate.

Bacterial communities associated with Chenopodium album and Stellaria media seeds from arable soils.

The bacterial community compositions in Chenopodium album and Stellaria media seeds recovered from soil (soil weed seedbank), from bulk soil, and from seeds harvested from plants grown in the same soils were compared. It was hypothesized that bacterial communities in soil weed seedbanks are distinct from the ones present in bulk soils. For that purpose, bacterial polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) fingerprints, made from DNA extracts of different soils and seed fractions, were analyzed by principal component analysis. Bacterial fingerprints from C. album and S. media seeds differed from each other and from soil. Further, it revealed that bacterial fingerprints from soil-recovered and plant-harvested seeds from the same species clustered together. Hence, it was concluded that microbial communities associated with seeds in soil mostly originated from the mother plant and not from soil. In addition, the results indicated that the presence of a weed seedbank in arable soils can increase soil microbial diversity. Thus, a change in species composition or size of the soil weed seedbank, for instance, as a result of a change in crop management, could affect soil microbial diversity. The consequence of increased diversity is yet unknown, but by virtue of identification of dominant bands in PCR-DGGE fingerprints as Lysobacter oryzae (among four other species), it became clear that bacteria potentially antagonizing phytopathogens dominate in C. album seeds in soil. The role of these potential antagonists on weed and crop plant growth was discussed.

ß-carboline alkaloids from Stellaria dichotoma var. lanceolata and their anti-inflammatory activity.

The present investigation on the chemical constituents of the roots of Stellaria dichotoma var. lanceolata has resulted in the isolation of 21 ß-carboline alkaloids, including 13 new compounds, dichotomides III-XIV (1-12) and dichotomine E (13), and eight known compounds. The structures of the new compounds were established on the basis of spectroscopic data analysis. Among these isolated alkaloids, five compounds were examined for their anti-inflammatory potential for the inhibition of NO production in LPS-treated RAW 264.7 cells. All compounds tested exhibited significant inhibition of NO production, with IC(50) values in the range of 11.3 to 19.3 µM.

Stress responses and nickel and zinc accumulation in different accessions of Stellaria media (L.) Vill. in response to solution pH variation in hydroponic culture.

In most non-hyperaccumulating plants, Ni and Zn uptake is negatively correlated with soil pH, however, few studies so far have investigated how pH influences the activity and uptake of Ni and Zn in plants grown in a hydroponic system, which generally allows culture variables to be singularly manipulated. In this study, the non-accumulator Stellaria media (L.) Vill. (Caryophyllaceae) had opposite trends of Ni and Zn uptake along a pH gradient (between 5 and 8 for Zn and between 5 and 6.5 for Ni), when grown in hydroponics. In all treatments, the solution metal concentration was fixed at 0.1 mM Ni or 0.55 mM Zn. Nickel accumulation increased with increasing pH with an average concentration in shoots of 167 µg/gDW at pH 5 and of 250 µg/gDW at pH 6.5. In contrast, Zn accumulation decreased with increasing pH, with an average concentration in shoots varying from 1640 µg/gDW, at pH 5, to 435 µg/gDW at pH 8. Assessment of total polyphenol and flavonoid contents and of antioxidant activity showed that these parameters were positively correlated with Ni or Zn accumulation in S. media shoots, while photosynthetic pigments content and root and shoot biomass were negatively correlated with Ni and Zn accumulation. The study was carried out on five different S. media populations, which did not show differences in relation to the accumulation of metals and synthesis of antioxidant compounds, nonetheless showing a different biomass production under control conditions.