Effect of cadmium on growth, ultramorphology of leaf and secondary metabolites of Phyllanthus amarus Schum. and Thonn

Unveiling the Dual Nature of Heavy Metals: Stressors and Promoters of Phenolic Compound Biosynthesis in Basilicum polystachyon (L.) Moench In Vitro

The global industrial revolution has led to a substantial rise in heavy metal levels in the environment, posing a serious threat to nature. Plants synthesize phenolic compounds under stressful conditions, which serve as protective agents against oxidative stress. Basilicum polystachyon (L.) Moench is an herbaceous plant of the Lamiaceae family. Some species within this family are recognized for their capacity to remediate sites contaminated with heavy metals. In this study, the effects of mercury (II) chloride and lead (II) nitrate on the in vitro propagation of B. polystachyon were investigated. Shoot tips from in vitro plantlets were cultured in Murashige and Skoog's (MS) media with heavy metals ranging from 1 to 200 µM to induce abiotic stress and enhance the accumulation of phenolic compounds. After three weeks, MS medium with 1 µM of lead (II) supported the highest shoot multiplication, and the maximum number of roots per explant was found in 100 µM of lead (II), whereas a higher concentration of heavy metals inhibited shoot multiplication and root development. The plantlets were hardened in a greenhouse with a 96% field survival rate. Flame atomic absorption spectroscopy (FAAS) was used to detect heavy metal contents in plant biomass. At both 200 µM and 50 µM concentrations, the greatest accumulation of mercury (II) was observed in the roots (16.94 ± 0.44 µg/g) and shoots (17.71 ± 0.66 µg/g), respectively. Similarly, lead (II) showed the highest accumulation in roots (17.10 ± 0.54 µg/g) and shoots (7.78 ± 0.26 µg/g) at 200 µM and 50 µM exposures, respectively. Reverse-phase high-performance liquid chromatography (RP-HPLC) identified and quantified various phenolic compounds in B. polystachyon leaves, including gallic acid, caffeic acid, vanillic acid, p-coumaric acid, ellagic acid, rosmarinic acid, and trans-cinnamic acid. These compounds were found in different forms, such as free, esterified, and glycosylated. Mercury (II)-exposed plants exhibited elevated levels of vanillic acid (1959.1 ± 3.66 µg/g DW), ellagic acid (213.55 ± 2.11 µg/g DW), and rosmarinic acid (187.72 ± 1.22 µg/g DW). Conversely, lead (II)-exposed plants accumulated higher levels of caffeic acid (42.53±0.61 µg/g DW) and p-coumaric acid (8.04 ± 0.31 µg/g DW). Trans-cinnamic acid was the predominant phenolic compound in control plants, with a concentration of 207.74 ± 1.45 µg/g DW. These results suggest that sublethal doses of heavy metals can act as abiotic elicitors, enhancing the production of phenolic compounds in B. polystachyon. The present work has the potential to open up new commercial opportunities in the pharmaceutical industry.

Urbanisation impacts plumage colouration in a songbird across Europe: Evidence from a correlational, experimental and meta-analytical approach

Urbanisation is accelerating across the globe, transforming landscapes, presenting organisms with novel challenges, shaping phenotypes and impacting fitness. Urban individuals are claimed to have duller carotenoid-based colouration, compared to their non-urban counterparts, the so-called 'urban dullness' phenomenon. However, at the intraspecific level, this generalisation is surprisingly inconsistent and often based on comparisons of single urban/non-urban populations or studies from a limited geographical area. Here, we combine correlational, experimental and meta-analytical data on a common songbird, the great tit Parus major, to investigate carotenoid-based plumage colouration in urban and forest populations across Europe. We find that, as predicted, urban individuals are paler than forest individuals, although there are large population-specific differences in the magnitude of the urban-forest contrast in colouration. Using one focal region (Malmö, Sweden), we reveal population-specific processes behind plumage colouration differences, which are unlikely to be the result of genetic or early-life conditions, but instead a consequence of environmental factors acting after fledging. Finally, our meta-analysis indicates that the urban dullness phenomenon is well established in the literature, for great tits, with consistent changes in carotenoid-based plumage traits, particularly carotenoid chroma, in response to anthropogenic disturbances. Overall, our results provide evidence for uniformity in the 'urban dullness' phenomenon but also highlight that the magnitude of the effect on colouration depends on local urban characteristics. Future long-term replicated studies, covering a wider range of species and feeding guilds, will be essential to further our understanding of the eco-evolutionary implications of this phenomenon.

A novel biochar-based composite hydrogel for removing heavy metals in water and alleviating cadmium stress in tobacco seedlings

A novel composite hydrogel (AM/CMC/B) synthesized from peanut shell biochar effectively adsorbs heavy metal Cd in water and reduces its toxicity to tobacco seedlings. The hydrogel, prepared via hydrothermal polymerization using acrylamide (AM), carboxymethyl cellulose (CMC), and peanut shell biochar (B), exhibited a maximum adsorption capacity of 164.83 mg g-1 for Cd2+ and followed a pseudo-second-order kinetic model. In pot experiments, the application of exogenous AM/CMC/B mitigated the inhibitory effects of Cd-contaminated soil on tobacco seedling growth. Addition of 10 mg kg-1 Cd resulted in improved phenotype, root system development, enhanced photosynthetic capacity, stomatal conductance (Gs), stomatal number, and increased antioxidant activity while reducing MDA content and leaf cell death. These findings highlight the potential of AM/CMC/B as an environmentally friendly adsorbent for Cd removal from water and for reducing Cd stress toxicity in tobacco and other plants.

Physiological and molecular mechanisms of medicinal plants in response to cadmium stress: Current status and future perspective

Medicinal plants have a wide range of uses worldwide. However, the quality of medicinal plants is affected by severe cadmium pollution. Cadmium can reduce photosynthetic capacity, lead to plant growth retardation and oxidative stress, and affect secondary metabolism. Medicinal plants have complex mechanisms to cope with cadmium stress. On the one hand, an antioxidant system can effectively scavenge excess reactive oxygen species produced by cadmium stress. On the other hand, cadmium chelates are formed by chelating peptides and then sequestered through vacuolar compartmentalization. Cadmium has no specific transporter in plants and is generally transferred to plant tissues through competition for the transporters of divalent metal ions, such as zinc, iron, and manganese. In recent years, progress has been achieved in exploring the physiological mechanisms by which medicinal plants responding to cadmium stress. The exogenous regulation of cadmium accumulation in medicinal plants has been studied, and the aim is reducing the toxicity of cadmium. However, research into molecular mechanisms is still lagging. In this paper, we review the physiological and molecular mechanisms and regulatory networks of medicinal plants exposed to cadmium, providing a reference for the study on the responses of medicinal plants to cadmium stress.

The ignored risk: heavy metal pollution of medicine and food homologous substances

A survey was conducted to investigate the effects of cadmium (Cd), arsenic (As), chromium (Cr), lead (Pb), and copper (Cu) in medicine and food homologous substances (MFHs) on human health. Nine common and typical MFHs (Dendrobium, Bulbus lilii, Poria, Semen nelumbinis, Radix puerariae, Gardenia jasminoides, Hordeum vulgare L, Semen coicis, and Ganoderma Karst) in the form of medicinal slices ready for decoction were purchased from pharmacies. Five among the MFHs (Dendrobium, Bulbus lilii, Poria, Semen nelumbinis, and Radix puerariae) were further obtained from a local field as raw materials for comparison. The results showed that raw materials of MFHs collected from the field had higher contents of heavy metal and greater health risks than medicinal slices purchased from pharmacy. Generally, the heavy metal residues in MFHs of different medicinal parts were different, and MFHs from roots or stems had significantly higher contents of heavy metals than those from fruits or seeds. Most importantly, the contents of Cd in Bulbus lilii and As in wild Poria from field were higher than the contents described in the Pharmacopoeia of the People's Republic of China (ChP). Non-carcinogenic and carcinogenic risk assessments revealed that Poria from field had larger non-carcinogenic and carcinogenic risks to human health; Bulbus lilii showed no non-carcinogenic risk but exhibited carcinogenic risks, whereas Cr showed carcinogenic risks in all samples. Given that MFHs are incorporated in regular foods, care should be taken to minimize health hazards caused by heavy metals to human. This study creates awareness on the safety issues associated with MFHs, and provides basic information for establishing the maximum allowable contents of medicinal and food substances in normal diets.

Cadmium toxicity in medicinal plants: An overview of the tolerance strategies, biotechnological and omics approaches to alleviate metal stress

Medicinal plants, an important source of herbal medicine, are gaining more demand with the growing human needs in recent times. However, these medicinal plants have been recognized as one of the possible sources of heavy metal toxicity in humans as these medicinal plants are exposed to cadmium-rich soil and water because of extensive industrial and agricultural operations. Cadmium (Cd) is an extremely hazardous metal that has a deleterious impact on plant development and productivity. These plants uptake Cd by symplastic, apoplastic, or via specialized transporters such as HMA, MTPs, NRAMP, ZIP, and ZRT-IRT-like proteins. Cd exerts its effect by producing reactive oxygen species (ROS) and interfere with a range of metabolic and physiological pathways. Studies have shown that it has detrimental effects on various plant growth stages like germination, vegetative and reproductive stages by analyzing the anatomical, morphological and biochemical changes (changes in photosynthetic machinery and membrane permeability). Also, plants respond to Cd toxicity by using various enzymatic and non-enzymatic antioxidant systems. Furthermore, the ROS generated due to the heavy metal stress alters the genes that are actively involved in signal transduction. Thus, the biosynthetic pathway of the important secondary metabolite is altered thereby affecting the synthesis of secondary metabolites either by enhancing or suppressing the metabolite production. The present review discusses the abundance of Cd and its incorporation, accumulation and translocation by plants, phytotoxic implications, and morphological, physiological, biochemical and molecular responses of medicinal plants to Cd toxicity. It explains the Cd detoxification mechanisms exhibited by the medicinal plants and further discusses the omics and biotechnological strategies such as genetic engineering and gene editing CRISPR- Cas 9 approach to ameliorate the Cd stress.

The Remediation in Enzyme’s Activities in Plants: Tea Waste as a Modifier to Improve the Efficiency of Growth of Helianthus annuus in Contaminated Soil

The remediation in plant enzymatic activities in Cd-contaminated soil was monitored through tea waste. Tea is an extensively used beverage worldwide with the release of a high quantity of tea waste utilized in the growing condition of Helianthus annuus on Cd metal contaminated soil. The study was a plan for the natural environmental condition in the greenhouse. For this purpose, four sets of plants were cultivated in triplicate and marked as (i) control, (ii) Cd stress plants, (iii) dry tea waste and Cd stress, and (iv) fresh tea waste and Cd stress. The improved efficiency of biochemical reactions in plants under Cd stress with tea waste treatment was the consequence of blocking Cd movement in the soil through adsorption on tea waste, showing that the tea waste effectively controls the mobility of Cd from the soil to the roots of the plants. Scan electron microscopy (SEM) validates the recovery of the leaves of the plants. The remediation of plant growth and enzyme activities such as amylase, peroxidase, nitrate reductase (NR), and nitrite reductase (NiR) under Cd metal-contaminated soil through tea waste was investigated. The source of tea waste in contaminated soil resulted in the recovery of the photosynthetic process and an improvement in amylase, NR, NiR, and peroxidase activities, thereby resulting in the recovery of pigments coupled with an increase in the biomass of the plants. It was suggested that tea waste acts as a good biosorbent of Cd and energy provider to the plants for normal enzyme activity under Cd stress and may be used by farmers in the future for safe and healthy crops as a cost-effective technology.

Multi-elements characteristic and potential risk of heavy metals in MOUTAN CORTEX from Anhui Province, China

To ensure the quality and safety of herbs, the content of 54 elements in MOUTAN CORTEX (MC) was determined by the ICP-AES and ICP-MS, and the health risks of Cu, As, Cd, Pb, Hg and rare earth elements (REEs) were assessed. These herbs were collected from 5 producing areas in Anhui Province, China, namely Wuhu, Tongling, Bozhou, Xuancheng and Chizhou. The multi-elements fingerprint identification of MC in Anhui Province was established. The total amount of macro-elements from Wuhu and Tongling is significantly lower than Bozhou. Among all MC from 5 producing areas, the highest content is Ca. Except for Bozhou, the content of macro-elements and REES in the other 4 origins of MC is from highest to lowest: Ca > K > Mg > Al > Fe > Na and Ce > La > Nd > Y > Pr > Er > Yb > Eu > Ho > Tb > Tm > Lu. The chemical forms of Cd in MC from Bozhou with the highest percentage were PH2O of high toxicity and migration, while the other 4 regions were PNaCl of low activity and mobility. There was a great difference in the content of inorganic elements and chemical forms of Cd between the MC produced from the plain (Bozhou) and the hilly areas (Wuhu, Tongling, Chizhou and Xuancheng). Except for Cd, the content of Cu, As, Pb and Hg in MC did not exceed the limit. The results of PTWIFact and ADI for Cd and REEs showed that MC herbs did not pose a risk to human health.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13762-022-04402-6.

Cadmium and lead differentially affect growth, physiology, and metal accumulation in guar (Cyamopsis tetragonoloba L.) genotypes

Phytoremediation is a strategy to employ plants to recover high quantities of metals in the soil into the harvestable parts such as shoots and roots. High levels of Cd and lead (Pb) in the soil cause several stress symptoms in plants including a decrease in growth, reduced root growth, and carbohydrate metabolism. In this study, Saravan and HGS-867 as local landrace and Indian guar variety were selected to investigate the effect of the application of Pb (0, 40, 150, and 200 mg/l) and the cadmium (0, 25, 50, and 100 mg/l) on phonological, yield parameters, and phytoremediation assessment. The results showed that Pb translocation factor (TF) was significant in Pb×Cd and Pb×Cd×G (genotype) at p<0.01 and in Pb×G at p<0.05. Pb bioconcentration factor (BCF) was significant (p<0.01) in all treatments except Cd and Cd×G treatments. Mean comparison of the data showed that the number of flowers, leaves, and clusters in plant decreased significantly with increasing Pb content. With increasing Cd concentration, the number of branches, height, the number of seeds, clusters, and leaves for each plant decreased significantly at the level of 1%. The maximum TF was observed in Pb at 40 mg/l in the HG-867 variety. Moreover, the Saravan landrace exposed to Cd (100 mg/l) showed the highest value of BCF (Cd). The gum percentage significantly decreased with increasing concentrations of Pb and Cd. Pearson's correlation analysis indicated that plant height, number of pods/plant, root length, biomass, and pod length had a positive correlation with seed yield and a negative correlation with TF (Pb) and BCF (Pb). The results suggest that according to TF, BCF, and BAC, C. tetragonoloba L. can be effectively used as a good accumulator of toxic metals in contaminated soils.

Ecophysiological, anatomical, and apigenin changes due to uptake and accumulation of cadmium in Matricaria chamomilla L. flowers in hydroponics

Cadmium (Cd) is one of the most important heavy metals in the environment which has several effects on the morphology, physiology, and anatomy of plants. It is a mobile heavy metal that can be transferred easily into plants, thus entering into the human food chain. Chamomile (Matricaria chamomilla L.) as an important medicinal plant can uptake and accumulate Cd in its root and aerial organs. In this research, the effects of different concentrations of Cd (90, 180, and 360 μM) were investigated on the growth parameters, anatomical features, and enzymatic antioxidant activities in flowers of chamomile after 7 days of exposure. The content of apigenin, a flavone compound mostly synthesizing in chamomile flowers, was also analyzed after 72 h from Cd treatment. The results showed that all concentrations of Cd reduced the length and biomass of roots and shoots, the diameter of flowers, as well as the number of pollen grains in tubular florets, while increased trichome density on the florets. Cd-treated plants showed an increase in antioxidant enzymes, superoxide dismutase (SOD), and peroxidase (POX) activities. After 7 days of treatment to Cd major concentration, flowers accumulated Cd and enhanced the apigenin production with the increase of Cd contamination in hydroponic solution. This increase of apigenin is most likely due to its antioxidant and sequestering property as a resistance response to Cd excess.

Irrigating digestate to improve cadmium phytoremediation potential of Pennisetum hybridum

The bioavailability of heavy metal and growth of hyperaccumulator are key factors controlling the phytoextraction of heavy metal from soil. In this study, the efficacy and potential microbial mechanisms of digestate application in enhancing Cd extraction from soil by Pennisetum hybridum were investigated. The results showed that digestate application significantly promoted the height, tiller number, and biomass yield of Pennisetum hybridum. The application also increased the activities of urease, sucrase, dehydrogenase, available Cd contents of rhizosphere soils (from 2.21 to 2.46 mg kg^-1), and the transfer factors of Cd from root to shoot and leaf. Assuming three annual harvests, digestate application would substantially reduce time needed for Pennisetum hybridum to completely absorb Cd from soil-from 15-16 yr-10 yr. Furthermore, the results of microbial community diversity analysis showed that digestate irrigation was more facilitated for the growth of the predominant bacteria, which were Actinobacteria and Chloroflexi at phylum level, and Sphingomonas and Nitrospiraat genus level, which mainly have the functions of promoted plant growth and metal resistance. The results suggested that the enhanced phytoextraction of Cd by Pennisetum hybridum with digestate application might mainly attributed to the increased Cd bio-availability and the enhanced plant growth, indicating that an approach combining digestate and Pennisetum hybridum could be a promising strategy for remediating Cd-contaminated soils.

Sewage Sludge as a Tool in Limiting the Content of Trace Elements in Avena sativa L. on the Soil Polluted with Diesel Oil

The aim of the research was to determine the effect of soil contamination with diesel oil (0; 5; 10 and 15 cm³ kg^-1 of soil) on the content of trace elements in the aboveground parts of oat (Avena sativa L.). Stabilised sewage sludge was used to mitigate the likely negative impact of diesel oil on the plant. Growing soil contamination with diesel oil had a significant impact on the content of trace elements in the aboveground biomass of oat. In the series without sewage sludge, the contents of the analysed elements, except for chromium, zinc, copper and cobalt, were positively correlated with the increasing doses of diesel oil. The largest increase in the content was recorded in the case of manganese. The sewage sludge used to reduce the influence of diesel oil on the chemical composition of oat had a positive effect on the content of the analysed trace elements. Compared to the series without the addition of a stabilised sewage sludge, it contributed to a reduction in the average content of chromium, nickel, copper, manganese and cobalt in the aboveground parts of oat plants. No significant effect of the applied remediation treatment was noted for cadmium, and the results were equivocal for iron.

Multi-element Characteristics of Chinese Medical Baishao (Paeoniae Radix Alba) and Their Decoctions

Adopting ICP-AES and ICP-MS to determine the content of 53 elements (6 macro-elements, 47 trace elements), which used HNO₃ (5 mL) and H₂O₂ (2 mL) to digest Baishao (Paeoniae Radix Alba) by microwave. These herbs obtained from six producing areas in China, namely Xuanwu (Henan province), Shihezi (Xinjiang province), Zhongjiang (Sichuan province), Panan (Zhejiang province), Bozhou (Anhui province), and Heze (Shandong province). A certified reference material of Astragalus (GBW 10028, GSB-19) was used to assess the accuracy of the method. Except the slight change of Na and S in Xuanwu, the content of other producing areas followed the order of Ca > K > P > Mg > S > Na. The herbs of Shihezi (22,658 mg/kg) got the highest concentration of total elements, while the herbs of Panan (1.006 mg/kg) got the highest concentration of rare earth elements. The multi-element fingerprint map of Baishao was established, which was obviously different from other herbs. Meanwhile, the same method was adopted to determine the content of 50 elements in Baishao decoctions from three main producing areas. Compared with the herbs, each element was significantly reduced, and K was the highest concentration. The transfer rates of elements in Baishao decoctions followed the order (mean): As (55.79%) > Ni (55.19%) > Na (51.48%) > Mo (44.13%) > Ce (43.82%) > V (40.52%). The decoctions of Panan (0.122 mg/kg) got the highest content of rare earth elements. In all Baishao herbs and their corresponding decoctions, the levels of Cu, Cd, As, Pb, and Hg did not exceed the limits of the Green Trade Standards of Importing & Exporting Medicinal Plants & Preparations (WM2-2001) and Chinese Pharmacopoeia (2015).

Antimony induced structural and ultrastructural changes in Trapa natans

Antimony (Sb) is considered as a priority toxic metalloid in the earth crust having no known biological function. The current study was carried out in a hydroponic experiment to study the accumulation of ecotoxic Sb in subcellular level, and to find out the ultrastructural damage caused by Sb in different vegetative parts of Trapa natans. Sb-induced structural and ultrastructural changes of T. natans were investigated using scanning electron microscope (SEM) and transmission electron microscope (TEM). Experimental plants were exposed to different Sb(III) treatments: SbT1 (1.5 μmol/L), SbT2 (40 μmol/L) and SbT3 (60 μmol/L). Calculated bioconcentration factor (BCF) and translocation factor (TF) showed that at higher concentration (SbT2, SbT3), T. natans is a potent phytoexcluder whereas it can translocate a substantial amount of Sb to the aerial parts at lower concentration (SbT1). SEM analysis revealed Sb-mediated structural changes in the size of stomatal aperture, intercellular spaces and vascular bundles of different vegetative tissues of T. natans. TEM results showed subcellular compartmentalization of Sb in vacuole and cell wall as electron dense deposition. This is considered as a part of strategy of T. natans to detoxify the deleterious effects under Sb stress conditions. Fourier transform infrared spectroscopy (FTIR) study of plant biomass revealed possible metabolites of T. natans which can bind Sb.

Overexpression of Trx CDSP32 gene promotes chlorophyll synthesis and photosynthetic electron transfer and alleviates cadmium-induced photoinhibition of PSII and PSI in tobacco leaves

Cadmium stress causes a decrease in chlorophyll content and inhibits photosynthesis in tobacco leaves. The role of thioredoxin-like protein CDSP32 expressed in plant chloroplasts is to alleviates the reduced enzymes expression involved in chlorophyll synthesis of tobacco leaves due to Cd exposure, effectively preventing chlorophyll degradation and promoting increased tobacco biomass. Overexpression of Trx CDSP32 can protect the oxygen-evolving complex on the PSII donor side and promote electron transfer on the PSII acceptor side of tobacco leaves under Cd stress. Trx CDSP32 not only significantly increase the PSI activity of tobacco leaves, but also alleviate cadmium-induced PSI photoinhibition. Although Trx CDSP32 has no significant effect on the expression of PC and FNR proteins in tobacco leaves under Cd stress, it can alleviate the decreased expression of protein subunits involved in photosynthetic electron transfer such as Cyt b6/f complex subunits, Fd, and ATP synthase subunits. Trx CDSP32 can promote the synthesis of chlorophyll, stabilize the electron transfer chain, and promote ATP synthase activity to alleviate cadmium-induced photoinhibition of PSII and PSI in tobacco leaves.

Litter decomposition process dramatically declines the allelopathy of Solidago canadensis L. on the seed germination and seedling growth of Lactuca sativa L

A variety of invasive alien species (IAS) can trigger distinct allelopathy on the seed germination and seedling growth (SGeSGr) of native plant species (NPS) mainly through the released allelochemicals. However, the decomposition process of IAS litters may affect their allelopathy on SGeSGr of NPS because part of the allelochemicals will be released during the litter decomposition process, especially under heavy metal pollution. This study focuses on the impacts of the litter decomposition process of the notorious IAS Solidago canadensis L. on its allelopathy on SGeSGr of NPS Lactuca sativa L. under cadmium (Cd) pollution. The decomposition process signally declines the allelopathy of S. canadensis litters on SGeSGr of L. sativa likely because partial allelochemicals in S. canadensis litters discharged during the decomposition process. Cd addition noticeably rises the allelopathy of S. canadensis litters on SGeSGr of L. sativa probably because Cd can reduce plant growth largely via the improved lipid membrane permeability and the induced reactive oxygen molecules which is unfavorable to plant cell metabolism. This phenomenon may also be attributed to the weak acid properties of one of the most abundant allelochemicals in S. canadensis litters, i.e., phenolics (particularly polyphenols), can improve the solubility and the toxicity of Cd.

Comparative Study of Growth, Cadmium Accumulation and Tolerance of Three Chickpea (Cicer arietinum L.) Cultivars

Trace metals (TM) contamination is a severe problem in the environment and produced an adverse effect on the productivity of crops. Cadmium (Cd) is a TM ranked seven among the top 20 pollutants due to its high toxicity and solubility in water, taken up by the plants and affects their growth and metabolism. In this study, we evaluated the growth, Cd accumulation and tolerance capacities of three chickpea (Cicer arietinum L.) cultivars (NC234 (NC2), ICCV89310 (IC8) and ICCV89323-B (IC8-B)), subjected to two Cd concentrations (25 and 50 µM) in hydroponic culture. The toxicity of Cd reduced the plant height and fresh and dry biomass in all cultivars. The maximum reduction was observed at 50 µM of Cd. Compared with IC8-B, cultivars IC8 and NC2 exhibited better performance with high growth, biomass, root to shoot (R/S) ratio and water content under high Cd stress. To measure the accumulation of Cd in root and shoot, an inductively coupled plasma optical emission spectrometer (ICP-OES) was used. IC8 and NC2 had comparatively high Cd tolerance and accumulation ability (> 100 µg g^-1 dry weight), with IC8 being more tolerant and accumulated higher Cd in shoot than NC2, while cultivar IC8-B was sensitive. Root accumulated more Cd than shoot in a dose-dependent manner. The bioconcentration factors (BCF) and bioaccumulation coefficients (BAC) were far higher than one (> 1) and increased with an increase in Cd concentrations, while the translocation factor (TF) was less than one (< 1), suggesting that all the three cultivars were unable to transfer Cd from the root to the shoot efficiently. Our results indicated that IC8 and NC2 proved to be resistant, while IC8-B showed sensitivity when exposed to high Cd stress (50 µM).

Eco-Friendly Estimation of Heavy Metal Contents in Grapevine Foliage Using In-Field Hyperspectral Data and Multivariate Analysis

Heavy metal monitoring in food-producing ecosystems can play an important role in human health safety. Since they are able to interfere with plants’ physiochemical characteristics, which influence the optical properties of leaves, they can be measured by in-field spectroscopy. In this study, the predictive power of spectroscopic data is examined. Five treatments of heavy metal stress (Cu, Zn, Pb, Cr, and Cd) were applied to grapevine seedlings and hyperspectral data (350–2500 nm), and heavy metal contents were collected based on in-field and laboratory experiments. The partial least squares (PLS) method was used as a feature selection technique, and multiple linear regressions (MLR) and support vector machine (SVM) regression methods were applied for modelling purposes. Based on the PLS results, the wavelengths in the vicinity of 2431, 809, 489, and 616 nm; 2032, 883, 665, 564, 688, and 437 nm; 1865, 728, 692, 683, and 356 nm; 863, 2044, 415, 652, 713, and 1036 nm; and 1373, 631, 744, and 438 nm were found most sensitive for the estimation of Cu, Zn, Pb, Cr, and Cd contents in the grapevine leaves, respectively. Therefore, visible and red-edge regions were found most suitable for estimating heavy metal contents in the present study. Heavy metals played a significant role in reforming the spectral pattern of stressed grapevine compared to healthy samples, meaning that in the best structures of the SVM regression models, the concentrations of Cu, Zn, Pb, Cr, and Cd were estimated with R² rates of 0.56, 0.85, 0.71, 0.80, and 0.86 in the testing set, respectively. The results confirm the efficiency of in-field spectroscopy in estimating heavy metals content in grapevine foliage.

Metal(loid) induced toxicity and defense mechanisms in Spinacia oleracea L.: Ecological hazard and Prospects for phytoremediation

A pot study was conducted to assess the phytoremediation potential of Spinach plants along with their physiological and biochemical response when grown in soil contaminated with heavy metal(loid)s (HMs). Plants were grown under different doses of Pb, Cd and As; and their metal(loid) accumulation efficiency was studied upon harvest; expressed in terms of bioabsorption coefficient (BAC), bioconcentration factor (BCF) and translocation factor (TF). Results showed significant (p ≤ 0.05) difference in physiological and biochemical mechanisms of plants as detected through decrease in concentration of cellular constituents (pigments, carbohydrates, total nitrogen content); and increase in antioxidants (both enzymatic and non-enzymatic). Despite of accumulating high amount of HMs in tissues, no visible signs of toxicity were seen; and hence the efficient survival and defense mechanism shown by spinach plants conclude that they are a viable option to be used for phytoremediation of sites contaminated with Cd and Pb. Since the content of Cd and Pb in edible part was higher than safe limits prescribed by USEPA, the present investigation also highlights the ecological hazards that may result upon cultivation of spinach in contaminated soil for agricultural purpose; or its accidental exposure to food chain when grown for phytoremediation.

Comparative assessment of Indian mustard (Brassica juncea L.) genotypes for phytoremediation of Cd and Pb contaminated soils

Heavy metal removal by phytoremediation bears a great potential to decontaminate soils and Brassica juncea L. (Indian mustard) seems to be a possible candidate species for this purpose. A field experiment was conducted to compare the efficiency of eighty Indian mustard cultivars for phytoextraction of cadmium (Cd) and lead (Pb) from bimetal contaminated soil. Our results indicated that total Cd and Pb concentrations in the shoots and roots were in the range of 2.43 ± 0.00 to 0.31 ± 0.02 mg/kg and 2.94 ± 0.05 to 0.44 ± 0.03 mg/kg and 5.33 ± 0.76 to 0.47 ± 0.20 mg/kg and 3.78 ± 0.06 to 0.16 ± 0.08 mg/kg. Significant differences based on the translocation factors indicated that root-to-shoot transfer is higher for Pb (3.87 ± 0.12 to 0.48 ± 0.03) than Cd (3.38 ± 0.05 to 0.22 ± 0.01). Furthermore, significant correlations between dry weights, Cd and Pb concentrations and uptake in both shoots and roots were observed, but translocation factor showed a negative correlation with roots, but not in shoots. Among 80 genotypes of Indian mustard IM-25, IM-13 and IM-65 for Cd and IM-79, IM-24 and IM-32 for Pb seems to perform well for phytoextraction. The results of the field experiment suggest that certain Brassica juncea L. cultivars are suitable for removal of Cd and Pb in low to moderately contaminated soils.

Stomatal Response of Maize (Zea mays L.) to Crude Oil Contamination in Soils

In this study, maize plant was cultured in soil contaminated with different levels of crude oil. The purpose was to investigate the change of soil properties, leaf physiological and chemical parameters, and phenanthrene content in the leaf. Results showed that soil water content significantly increased when the levels of total petroleum hydrocarbons were 3700–17,800 mg/kg in soil, and soil electrical conductivity significantly increased compared with the control. In maize leaf, stomatal length and density, as well as K and Na contents decreased in contaminated treatments compared with the control. Stomatal length has a significant positive correlation with K content in leaf (r = 0.92, p < 0.01), while stomatal density was negatively correlated to the crude oil level in soil (r = −0.91, p < 0.05). Accumulation of phenanthrene in maize leaf was mainly through the foliar uptake pathway. Phenanthrene concentrations of maize leaf in oil-treated soil were less than that of the control, which exhibited a significant positive relationship with stomatal length (r = 0.98, p < 0.01). This study demonstrated that the stomata structure of maize could be influenced by crude oil and thus possibly controlling the accumulation of polycyclic aromatic hydrocarbons in aerial tissues. Based on these results, controlling stomata movement will be beneficial to phytoremediation of contaminated soil.

Detection of Cadmium Risk to the Photosynthetic Performance of Hybrid Pennisetum

Photosynthesis plays an essential role in plant growth and crop yield, and the mechanisms of the effects of cadmium (Cd) on photosynthetic performance require more attention. The acute toxicity of Cd in soil to the photosynthetic capacity of Hybrid Pennisetum was evaluated using gas exchange parameters, A/Ci curves, light response curves, and chlorophyll a fluorescence transients after exposure to elevated Cd concentrations (0, 10, 20, 50, 70, and 100 mg kg-1) for a 3-month period. The results indicated that leaf Cd concentration in Hybrid Pennisetum increased with the strength of soil Cd stress and ranged from 4.9 to 15.8 μg g-1 DW. The accumulation of leaf Cd severely restricted photosynthesis and its non-stomatal limitation in regulating the photosynthetic performance of Hybrid Pennisetum. The leaf chloroplasts at 10 and 20 mg kg-1 Cd concentrations showed no noticeable change, but the chlorophyll content significantly decreased by 9.0-20.4% at 50-100 mg kg-1 Cd concentrations. The Cd treatments also decreased plant ribulose-1,5-bisphosphate (RuBP) activity (Vcmax ) and regeneration capacity (Jmax ), triose phosphate utilization (TPU), light-saturated photosynthesis (Amax ), apparent quantum yield (AQY), light saturation point (LSP), and dark respiration (Rday ), but Cd treatment increased the light compensation point (LCP). The shape of chlorophyll a fluorescence transients in leaves was altered under different Cd treatments. The increased OJ phase and the decreased IP phase in fluorescence induction curves suggested that Cd toxicity inhibited both light use efficiency and photodamage avoidance ability. These results suggested that the decrease in photosynthesis through exposure to Cd may be a result of the decrease in leaf chlorophyll content, Rubisco activity, and RuBP regeneration, inhibition of triose phosphate utilization, reduction of the ability to use light and provide energy, and restrictions on electron transport in PSII.

ROS management is mediated by ascorbate-glutathione-α-tocopherol triad in co-ordination with secondary metabolic pathway under cadmium stress in Withania somnifera

Being static, plants are frequently exposed to various essential and non-essential heavy metals from the surroundings. This exposure results in considerable ROS generation leading to oxidative stress, the primary response of the plants under heavy metal stress. Withania somnifera is a reputed Indian medicinal plant in Ayurveda, having various pharmacological activities due to the presence of withanolides. The present study deals with the understanding endurance of oxidative stress caused by heavy metal exposure and its management through antioxidant partners in synchronization with secondary metabolites in W. somnifera. The quantitative assessment of enzymatic/non-enzymatic antioxidants revealed significant participation of ascorbate-glutathione-α-tocopherol triad in ROS management. Higher activities of glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) resulted in glutathione and ascorbate accumulation. In addition, superoxide dismutase (SOD), glutathione peroxidase (GPX) and peroxidase (POD) were contributed considerably in ROS homeostasis maintenance. In-situ localization and assays related to ROS generation/scavenging revealed key management of ROS status under Cd stress. Higher antioxidative and reducing power activity attributed to the tolerance capability to the plant. Increased expression of withanolide biosynthetic pathway genes such as WsHMGR, WsDXS, WsDXR and WsCAS correlated with enhanced withanolides. The present study indicated the crucial role of the ascorbate-glutathione-α-tocopherol triad in co-ordination with withanolide biosynthesis in affording the oxidative stress, possibly through a cross-talk between the antioxidant machinery and secondary metabolite biosynthesis. The knowledge may be useful in providing the guidelines for developing abiotic stress resistance in plants using conventional and molecular approaches.

ACCUMULATION BEHAVIOUR OF ALLANTOIN IN THE UNDERGROUND PHYTOMASS OF THE BORAGINACEAE FAMILY AND ITS ROLE IN ADAPTING THE PLANTS TO ADVERSE ENVIRONMENTAL FACTORS

Aim.The aim of the work described herein was to study the dynamics of allantoin accumulation in the underground phytomass ofEchium vulgareL.,Symphytum caucasicumM. Bieb. andS. asperumLepech. as well as to clarify the role of allantoin in plant adaptation to stress factors.

Methods.We studied the roots of plants growing in the foothill (Nalchik, 490–512 m above sea level) and the mountain zones of the Kabardino-Balkarian Republic (Terskol village, 2530 m above sea level; Verkhnyaya Balkaria village, 2680 m above sea level). The roots were collected at the stages of rosetting, flowering, fruiting and at the end of the growing season. Aqueous-alcoholic extracts of shredded roots were analyzed by high-performance liquid chromatography.

Results.The highest content of allantoin in the roots ofEchium vulgare,Symphytum caucasicum,S. asperumplants was noted at the end of the growing season, respectively 0.915; 0.342–0.658; 2,842–3,426%. Under conditions of low temperatures and increased solar radiation, the content of allantoin in the roots increases 1.2–1.9 times as compared with the plants of the foothill zone.

Conclusion.Allantoin plays an important role in the process of adapting species of the family Boraginaceae to oxidative stress caused by hypothermia and increased solar radiation.

Heavy metal pollution and potential health risks of commercially available Chinese herbal medicines

A survey was conducted to investigate the pollution and health risks of copper (Cu), cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg) and zinc (Zn) in 60 Chinese herbal medicines (CHMs) collected from a market in Kunming City, Yunnan Province, China. Furthermore, eight CHMs (Cyathulae radix, Drynariae rhizoma, Peucedani radix, Homalomenae rhizoma, Dryopteris setosa, Polygonati rhizoma, Lilii bulbus, and Linderae radix) containing high Cd concentrations were selected to further analyse their Cd chemical forms. Additionally, the dissolution rates of six heavy metals in decoction liquid were also analysed for four CHMs (Typhonii rhizoma, Linderae radix, Homalomenae rhizoma, and Cyathulae radix), and the health risks of heavy metals in CHMs were evaluated. The results showed that the Cd, Hg and Cu concentrations in the 60 CHMs exceeded the limiting values of the "Green Trade Standards of Importing & Exporting Medicinal Plants & Preparations" (WM2-2001), with exceedance ratios of 38.8%, 8.3% and 1.7%, respectively. The majority of Cd was integrated with pectates and protein in CHMs, and the other five Cd chemical forms followed the order of water-soluble > insoluble heavy metal phosphates > oxalate > residual > inorganic form, indicating that Cd had relatively low bioactivity and toxicity. The average dissolution rates of Zn, Cu, Cd, Hg, As and Pb in the four CHMs were 47.4%, 33.8%, 20.5%, 6.1%, 5.4% and 4.8%, respectively. The calculation results of hazard quotients (HQs) for Cd and Hg showed that the CHMs did not pose a threat to human health.

Cadmium accumulation and its effects on physiological and biochemical characters of summer savory (Satureja hortensis L.)

The objective of this study was to determine the effects of cadmium (Cd) toxicity on accumulation, growth, physiological responses, and biochemical characters in summer savory (Satureja hortensis L.). Plants were subjected to different levels of Cd concentrations including 0 (control), 2.5, 5, and 15 mg L^-1 in the growing medium. Cd exposure led to a significant increase in root and shoot Cd content. Calculation of bioaccumulation factor, translocation factor, and transfer coefficient revealed that Cd mostly accumulated in roots of S. hortensis and root to shoot transport was effectively restricted. Cd toxicity negatively affected plant growth and significantly reduced chlorophyll content. Contrarily, proline, soluble and reducing carbohydrates, anthocyanin content, and the activity of antioxidant enzymes significantly increased as a result of Cd exposure. Cd application led to a significant increase in essential oil content of S. hortensis. GC-MS analysis revealed that percentage main constitute of S. hortensi, carvacrol, which determines the quality of oil increased under the highest Cd treatment. Based on our findings, S. hortensis can be considered an invaluable alternative crop for mildly Cd-contaminated soils. Besides, due to the high potential of Cd accumulation in the root, S. hortensis may offer a feasible tool for phytostabilization purposes.

The Role of Heavy Metals in Plant Response to Biotic Stress

The present review discusses the impact of heavy metals on the growth of plants at different concentrations, paying particular attention to the hormesis effect. Within the past decade, study of the hormesis phenomenon has generated considerable interest because it was considered not only in the framework of plant growth stimulation but also as an adaptive response of plants to a low level of stress which in turn can play an important role in their responses to other stress factors. In this review, we focused on the defence mechanisms of plants as a response to different metal ion doses and during the crosstalk between metal ions and biotic stressors such as insects and pathogenic fungi. Issues relating to metal ion acquisition and ion homeostasis that may be essential for the survival of plants, pathogens and herbivores competing in the same environment were highlighted. Besides, the influence of heavy metals on insects, especially aphids and pathogenic fungi, was shown. Our intention was also to shed light on the relationship between heavy metals deposition in the environment and ecological communities formed under a strong selective pressure.

Untargeted UPLC-Q/TOF-MS-based metabolomics and inductively coupled plasma optical emission spectroscopic analysis reveal differences in the quality of ginger from two provinces in Zambia

OBJECTIVES

This study sought to investigate the differences in the quality of dried ginger samples obtained from two places in Zambia, Lusaka and Copperbelt in terms of their secondary metabolite differences and heavy metals content.

METHODS

Ten and eight batches of dried ginger obtained, respectively, from Lusaka and Copperbelt were analysed using untargeted Q/TOF-MS-based metabolomics and inductively coupled plasma optical emission spectroscopy (ICP-OES).

KEY FINDINGS

The metabolomics approach yielded 11 differential metabolites that clearly discriminated between the samples from the two locations. Eight were found to be more abundant in the samples from Lusaka while three were present in greater amounts in the samples from Copperbelt. The results of the heavy metal content analysis for four selected elements, Cd, Pb, As and Cu, showed that the samples from Copperbelt recorded higher levels. However, all samples contained levels of the toxic metals, Cd and Pb above permissible limits, making them unwholesome for human consumption.

CONCLUSIONS

The outcome of the heavy metal content analysis led us to speculate that abiotic stress as a result of these metals experienced by the ginger rhizomes during cultivation could have contributed to the metabolites abundance differences. Further studies are, however, recommended to verify this hypothesis.

Contamination of soil and the medicinal plant Phyllanthus niruri Linn. with cadmium in ceramic industrial areas

Phyllanthus niruri is a plant that is used to prevent calcium oxalate crystallisation and to block the stone formation in urolithiasis. Contaminants in the environment can be readily taken up by medicinal plants due to their ability to absorb chemicals into their tissues. If contaminated plants are ingested, they have the potential to negatively affect human and environmental health. The aim of this study was to assess contamination in the soil and the medicinal plant P. niruri by cadmium (Cd) in ceramic industrial areas of Monte Carmelo, Brazil. Soil samples and plant samples (divided in root, shoot and leaves) were collected from a contaminated monitoring site and from a rural area (which was used as a reference site for comparative purposes). The Cd concentrations of the samples were analysed with an atomic absorption spectrometer. P. niruri was found to be sensitive to soil contamination by Cd that was attributed to ceramic industrial emissions. The results revealed that Cd bioaccumulation in the roots and shoots of P. niruri was associated with a significant increase (p < 0.05) in the concentration of active lignan compounds (phyllanthin and hypophyllanthin) in the leaves. The identification of high concentrations of Cd and active lignan compounds suggests a risk of contamination of the site and the risk of a high dose of Cd to people exposed at the site.

Improved production of dibenzocyclooctadiene lignans in the elicited microshoot cultures of Schisandra chinensis (Chinese magnolia vine)

Dibenzocyclooctadiene lignans are a specific group of secondary metabolites that occur solely in Schisandra chinensis. The aim of the presented work was to boost the accumulation of lignans in the agitated microshoot cultures of S. chinensis, using different elicitation schemes. The experiments included testing of various concentrations and supplementation times of cadmium chloride (CdCl₂), chitosan (Ch), yeast extract (YeE), methyl jasmonate (MeJa), and permeabilizing agent—dimethylsulfoxide (DMSO). After 30 days, the microshoots were harvested and evaluated for growth parameters and lignan content by LC-DAD method. The analyses showed enhanced production of lignans in the elicited S. chinensis microshoots, whereas the respective media samples contained only trace amounts of the examined compounds (< 5 mg/l). Elicitation with CdCl₂ caused up to 2-fold increase in the total lignan content (max. ca. 730 mg/100 g DW after the addition of 1000 μM CdCl₂ on the tenth day). Experiments with chitosan resulted in up to 1.35-fold increase in lignan concentration (max. ca. 500 mg/100 g DW) after the supplementation with 50 mg/l on the first day and 200 mg/l on the tenth day. High improvement of lignan production was also recorded after YeE elicitation. After the elicitation with 5000 mg/l of YeE on the first day of the growth period, and with 1000 and 3000 mg/l on the 20th day, the lignan production increased to the same degree—about 1.8-fold. The supplementation with 1000 mg/l YeE on the 20th day of the growth cycle was chosen as the optimal elicitation scheme, for the microshoot cultures maintained in Plantform temporary immersion system—the total content of the estimated lignans was equal to 831.6 mg/100 g DW.

Heavy metals in contaminated environment: Destiny of secondary metabolite biosynthesis, oxidative status and phytoextraction in medicinal plants

Contamination of soils, water and air with toxic heavy metals by various human activities is a crucial environmental problem in both developing and developed countries. Heavy metals could be introduced into medicinal plant products through contaminated environment (soil, water and air resources) and/or poor production practices. Growing of medicinal plants in heavy metal polluted environments may eventually affect the biosynthesis of secondary metabolites, causing significant changes in the quantity and quality of these compounds. Certain medicinal and aromatic plants can absorb and accumulate metal contaminants in the harvestable foliage and, therefore, considered to be a feasible alternative for remediation of polluted sites without any contamination of essential oils. Plants use different strategies and complex arrays of enzymatic and non-enzymatic anti-oxidative defense systems to cope with overproduction of ROS causes from the heavy metals entered their cells through foliar and/or root systems. This review summarizes the reports of recent investigations involving heavy metal accumulation by medicinal plants and its effects on elicitation of secondary metabolites, toxicity and detoxification pathways, international standards regarding in plants and plant-based products, and human health risk assessment of heavy metals in soil-medicinal plants systems.

Sources, distribution, bioavailability, toxicity, and risk assessment of heavy metal(loid)s in complementary medicines

The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use of complementary medicines is the presence of heavy metal(loid)s such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). This review deals with the characteristics of complementary medicines in terms of heavy metal(loid)s sources, distribution, bioavailability, toxicity, and human risk assessment. The heavy metal(loid)s in these medicines are derived from uptake by medicinal plants, cross-contamination during processing, and therapeutic input of metal(loid)s. This paper discusses the distribution of heavy metal(loid)s in these medicines, in terms of their nature, concentration, and speciation. The importance of determining bioavailability towards human health risk assessment was emphasized by the need to estimate daily intake of heavy metal(loid)s in complementary medicines. The review ends with selected case studies of heavy metal(loid) toxicity from complementary medicines with specific reference to As, Cd, Pb, and Hg. The future research opportunities mentioned in the conclusion of review will help researchers to explore new avenues, methodologies, and approaches to the issue of heavy metal(loid)s in complementary medicines, thereby generating new regulations and proposing fresh approach towards safe use of these medicines.

Cadmium toxicity investigated at the physiological and biophysical levels under environmentally relevant conditions using the aquatic model plant Ceratophyllum demersum

Cadmium (Cd) is an important environmental pollutant and is poisonous to most organisms. We aimed to unravel the mechanisms of Cd toxicity in the model water plant Ceratophyllum demersum exposed to low (nM) concentrations of Cd as are present in nature. Experiments were conducted under environmentally relevant conditions, including nature-like light and temperature cycles, and a low biomass to water ratio. We measured chlorophyll (Chl) fluorescence kinetics, oxygen exchange, the concentrations of reactive oxygen species and pigments, metal binding to proteins, and the accumulation of starch and metals. The inhibition threshold concentration for most parameters was 20 nM. Below this concentration, hardly any stress symptoms were observed. The first site of inhibition was photosynthetic light reactions (the maximal quantum yield of photosystem II (PSII) reaction centre measured as Fv /Fm , light-acclimated PSII activity ΦPSII , and total Chl). Trimers of the PSII light-harvesting complexes (LHCIIs) decreased more than LHC monomers and detection of Cd in the monomers suggested replacement of magnesium (Mg) by Cd in the Chl molecules. As a consequence of dysfunctional photosynthesis and energy dissipation, reactive oxygen species (superoxide and hydrogen peroxide) appeared. Cadmium had negative effects on macrophytes at much lower concentrations than reported previously, emphasizing the importance of studies applying environmentally relevant conditions. A chain of inhibition events could be established.

The Stimulatory Effect of Strontium Ions on Phytoestrogens Content in Glycine max (L.) Merr

The amount of secondary metabolites in plants can be enhanced or reduced by various external factors. In this study, the effect of strontium ions on the production of phytoestrogens in soybeans was investigated. The plants were treated with Hoagland's solution, modified with Sr(2+) with concentrations ranging from 0.5 to 3.0 mM, and were grown for 14 days in hydroponic cultivation. After harvest, soybean plants were separated into roots and shoots, dried, and pulverized. The plant material was extracted with methanol and hydrolyzed. Phytoestrogens were quantified by HPLC. The significant increase in the concentration of the compounds of interest was observed for all tested concentrations of strontium ions when compared to control. Sr(2+) at a concentration of 2 mM was the strongest elicitor, and the amount of phytoestrogens in plant increased ca. 2.70, 1.92, 3.77 and 2.88-fold, for daidzein, coumestrol, genistein and formononetin, respectively. Moreover, no cytotoxic effects were observed in HepG2 liver cell models after treatment with extracts from 2 mM Sr(2+)-stressed soybean plants when compared to extracts from non-stressed plants. Our results indicate that the addition of strontium ions to the culture media may be used to functionalize soybean plants with enhanced phytoestrogen content.

Coloured ornamental traits could be effective and non-invasive indicators of pollution exposure for wildlife

Growth in human populations causes habitat degradation for other species, which is usually gauged by physical changes to landscapes. Corresponding habitat degradation to air and water is also common, but its effects on individuals can be difficult to detect until they result in the decline or disappearance of populations. More proactive measures of pollution usually combine abiotic samples of soil, water or air with invasive sampling of expendable species, but this approach sometimes creates ethical dilemmas and has limited application for threatened species. Here, we describe the potential to measure the effects of pollution on many species of birds and fish by using ornamental traits that are expressed as coloured skin, feathers and scales. As products of sexual selection, these traits are sensitive to environmental conditions, thereby providing honest information about the condition of their bearers as ready-made biomarkers. We review the documented effects of several classes of pollutants, including pharmaceuticals, pesticides, industry-related compounds and metals, on two classes of colour pigments, namely melanins and carotenoids. We find that several pollutants impede the expression of both carotenoids and brown melanin, while enhancing traits coloured by black melanin. We also review some of the current limitations of using ornamental colour as an indicator of pollution exposure, suggest avenues for future research and speculate about how advances in robotics and remote imagery will soon make it possible to measure these traits remotely and in a non-invasive manner. Wider awareness of this potential by conservation managers could foster the development of suitable model species and comparative metrics and lay a foundation for pollution monitoring that is more generalizable and biologically relevant than existing standards.

Effects of Cd and Al stress on secondary metabolites, antioxidant and antibacterial activity of Hypoxis hemerocallidea Fisch. & C.A. Mey

This study investigated the effects of cadmium (Cd) and aluminium (Al) on the accumulation of phenolics, flavonoids and the bioactive compound hypoxoside in Hypoxis hemerocallidea. In addition, antioxidant scavenging and antibacterial activity were assessed to evaluate if Cd and Al stress affect the accumulation of bioactive compounds in H. hemerocallidea. In vitro grown plantlets of H. hemerocallidea were acclimatized for seven months in a greenhouse. Thereafter plants were exposed to various concentrations of Cd and Al both singularly and in combination in the form of Cd(NO3)2 (2, 5, 10 mg Cd/L); Al3(NO3)3 (500, 1000, 1500 mg Al/L) and combinations of Cd and Al (Cd 2:Al 500, Cd 5:Al 1000 and Cd 10:Al 1500 mg/L) for a further six weeks. The highest amounts of Cd and Al translocated to the shoot were 34 and 1608 mg/L respectively. Phytochemical screening showed significantly high amounts of total phenolics and flavonoids at the moderate Cd treatment (5 mg/L) compared to the controls. Exposure to Cd and Al significantly decreased the accumulation of hypoxoside. There was a significant increase in diphenylpicrylhydrazyl (DPPH) antioxidant scavenging activity in most of the metal-treated plants compared to the positive control ascorbic acid. Extracts from Cd 2 mg/L treatment exhibited moderate antibacterial activity against Staphylococcus aureus compared to the control. The results of the present study revealed that cultivating H. hemerocallidea on metal contaminated soils affects the accumulation of the bioactive compound, hypoxoside.

Mechanism of Cr(VI) reduction by Aspergillus niger: enzymatic characteristic, oxidative stress response, and reduction product

Bioremediation of hexavalent chromium by Aspergillus niger was attributed to the reduction product (trivalent chromium) that could be removed in precipitation and immobilized inside the fungal cells and on the surface of mycelium. The site location of reduction was conducted with assays of the permeabilized cells, cell-free extracts, and cell debris, which confirmed that the chromate reductase was mainly located in the soluble fraction of cells. The oxidation-reduction process was accompanied by the increase of reactive oxygen species and antioxidant levels after hexavalent chromium treatment. Michaelis-Menten constant (K(m)) and maximum reaction rate (V(max)), obtained from the Lineweaver-Burk plot were 14.68 μM and 434 μM min(-1) mg(-1) of protein, respectively. Scanning electron microscopy and Raman spectra analyses manifested that both Cr(VI) and Cr(III) species were present on the mycelium. Fourier transform-infrared spectroscopy analysis suggested that carboxyl, hydroxide, amine, amide, cyano-group, and phosphate groups from the fungal cell wall were involved in chromium binding by the complexation with the Cr(III) and Cr(VI) species. A Cr(VI) removal mechanism of Cr(VI) reduction followed by the surface immobilization and intracellular accumulation of Cr(III) in living A. niger was present.

Effect of cadmium on growth, photosynthesis, mineral nutrition and metal accumulation of bana grass and vetiver grass

An experiment was conducted to evaluate the differential effects of Cd contamination on the growth, photosynthesis, mineral nutrition and Cd accumulation of bana grass (Pennisetum americanum × Pennisetum purpureum) and vetiver grass (Vetiveria zizanioides). Bana grass accumulated 48-453 and 25-208 mg kg(-1) in plant roots and shoots, respectively, at 15-100 mg kg(-1) soil Cd concentration, while vetiver grass accumulated 167-396 and 0.13-9.0 mg kg(-1). These results indicated that bana grass was a Cd accumulator while vetiver grass was a Cd excluder. The ratio of root to shoot biomass was significantly increased in vetiver grass, while it was unchanged in bana grass by Cd pollution. This suggests that excluders may allocate more energy to roots than shoots under Cd pollution compared to un-contaminated condition, while accumulators may allocate equal proportions of energy to roots and shoots. For bana grass, soil Cd pollution significantly decreased the concentration of Fe and Mn in roots as well as the translocation factors of Zn and K. For vetiver grass, soil Cd pollution significantly decreased the concentration of Fe in roots and had no influence on the translocation factors of Fe, Mn, Cu, Zn, Mg, K and Ca. Soil Cd pollution showed no significant effect on chlorophyll content and photosynthetic rates in either of the grasses. The water content and leaf transpiration rate were significantly increased by Cd pollution in bana grass, while they were unchanged in vetiver grass. The results indicated that the energy allocation and mineral nutrition characteristics may aid in screening suitable plant species for phytoremediation.

Vertisol prevent cadmium accumulation in rice: analysis by ecophysiological toxicity markers

Alfisol and vertisol cover more than fifty percent of rice fields in Asia. Rice cultivated in these soils is found to be contaminated with cadmium (Cd). Influence of physiochemical properties of these soils on Cd accumulation and ecophysiological functions of Oryza sativa L. cv MTU 7029 and MO 16 were analyzed. Plants grown in vertisol accumulated lower amount of Cd compare with those in alfisol. Soil properties such as cation exchange capacity and alkalinity played major role in decrease in Cd accumulation. Difference in Cd accumulation also reflected as more decrease in ecophysiological components such as biomass, relative water content and non-photochemical quenching among plants grown in alfisol. Plants grown in vertisol produced more flavanols, chlorophyll, anthocyanin, sugar, and protein than those in alfisol under Cd stress. But phenolic content was higher in plants grown in alfisol. Quantum efficiency of PSII, thiols, and silicon was increased while carotenes and calcium were decreased upon Cd accumulation. These changes were irrespective of soil type. Among the varieties chosen for the study, MTU 7029 accumulated more Cd compare with MO 16. It was concluded that soil properties caused difference in Cd accumulation among the plants grown in soils chosen and this would differentially reflect on specific ecophysiological markers.

Effect of chromium on antioxidant potential of Catharanthus roseus varieties and production of their anticancer alkaloids: vincristine and vinblastine

Catharanthus roseus (L.) G. Don, a medicinal plant, has a very important place in the traditional as well as modern pharmaceutical industry. Two common varieties of this plant rosea and alba are named so because of pink and white coloured flowers, respectively. This plant comprises of about 130 terpenoid indole alkaloids and two of them, vincristine and vinblastine, are common anticancer drugs. The effect of chromium (Cr) on enzymatic and non-enzymatic antioxidant components and on secondary metabolites vincristine and vinblastine was studied under pot culture conditions of both varieties of C. roseus. Antioxidant responses of these varieties were analyzed under 0, 10, 50, and 100  μM chromium (Cr) level in order to investigate the plant's protective mechanisms against Cr induced oxidative stress. The results indicated that Cr affects all the studied parameters and decreases growth performance. However, vincristine and vinblastine contents were increased under Cr stress. Results are quite encouraging, as this plant shows good antioxidant potential and increased the level of active constituents under Cr stress.

Effect of cadmium on growth, bacoside A, and bacopaside I of Bacopa monnieri (L.), a memory enhancing herb

Bacopa monnieri (L.) is an important medicinal plant mainly known as a memory enhancing herb. It is important to see the effect of metal pollution on its active constituents. In this context, efforts have been made to observe the effect of Cd on the triterpenoid saponins bacoside A and bacopaside I in this plant. The influence of the metal on growth parameters like protein, chlorophyll content, and biomass has also been observed. It is interesting to note that the bacoside A and bacopaside I gradually increased by the Cd treatment up to 10 μM and then decreased at higher concentrations, that is, 50 and 100 μM, but the concentration of these components was more in all the treated plants as compared to control. On the contrary, protein, chlorophyll content, and biomass decreased with the increase in metal concentration and exposure duration due to metal toxicity.

Variation in cadmium tolerance and accumulation and their relationship in wheat recombinant inbred lines at seedling stage

In order to identify the variation of cadmium (Cd) tolerance and accumulation in wheat (Triticum aestivum L.), a study was conducted in hydroponic culture with or without Cd using recombinant inbred lines (RILs) consisting of 103 RILs derived from a cross of Chuan 35050 × Shannong 483 at seedling stage. The parameters of shoot height, secondary roots numbers, tiller numbers, shoot dry weights, root dry weights, and maximum efficiency of photosystem II photochemistry under dark-adopted conditions were measured. Cd-tolerant indexes were then calculated as relative the above traits under Cd stress to those under the control. Cd concentration in shoot or root was determined and Cd accumulation and translocation were calculated. Based on the Cd-tolerant indexes, membership function analysis was used to determine the variation of the above parameters. The results showed a continuous distribution among the RILs and then the RILs were divided into five groups according to their tolerance. Lines 76 and 17 were considered as the most Cd-tolerant lines while lines 103 and 51 were as the most Cd-sensitive lines. Meanwhile, lines 38 and 79 were with minimum Cd translocation ratio while lines 88 and 53 were with maximum Cd translocation ratio, respectively. The relationship between Cd tolerance and accumulation was not significant, indicating Cd tolerance and accumulation may be independent traits in the RILs. Thus, lines with high Cd tolerance and less Cd accumulation could be selected for wheat breeding.

Molecular phylogenetic analysis of Phyllanthus species in Thailand and the application of polymerase chain reaction-restriction fragment length polymorphism for Phyllanthus amarus identification

The genus Phyllanthus (Phyllanthaceae) is distributed in tropical and subtropical regions, and its members are widely used as medicinal plants in many countries. We analyzed the nucleotide sequences of the internal transcribed spacers of ribosomal DNA of 56 plant samples covering 23 Phyllanthus species collected from various habitats in Thailand. Based on the sequence alignment, we constructed phylogenetic trees of all Phyllanthus species distributed in Thailand. Furthermore, a simple protocol to discriminate three important medicinal Phyllanthus species, P. amarus, P. debilis, and P. urinaria, was developed using a Polymerase Chain Reaction-Restriction Fragment Length Polymorphism method and successfully applied to the crude drug samples obtained in Thai markets.

Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants

Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. The ROS comprises both free radical (O(2)(-), superoxide radicals; OH, hydroxyl radical; HO(2), perhydroxy radical and RO, alkoxy radicals) and non-radical (molecular) forms (H(2)O(2), hydrogen peroxide and (1)O(2), singlet oxygen). In chloroplasts, photosystem I and II (PSI and PSII) are the major sites for the production of (1)O(2) and O(2)(-). In mitochondria, complex I, ubiquinone and complex III of electron transport chain (ETC) are the major sites for the generation of O(2)(-). The antioxidant defense machinery protects plants against oxidative stress damages. Plants possess very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaicol peroxidase, GOPX and glutathione-S- transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids and α-tocopherols) antioxidant defense systems which work in concert to control the cascades of uncontrolled oxidation and protect plant cells from oxidative damage by scavenging of ROS. ROS also influence the expression of a number of genes and therefore control the many processes like growth, cell cycle, programmed cell death (PCD), abiotic stress responses, pathogen defense, systemic signaling and development. In this review, we describe the biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery.

Heavy metals alter the potency of medicinal plants

There has been increased use of herbal drugs in recent years. Because of increasing demand and wider use, it is essential that the quality of plant-based drugs should be assured prior to use. When heavy metals contaminate the plants from which herbal drugs are derived, they affect both plant growth characteristics and production of secondary plant metabolites. Plants exposed to heavy metal stress show changes in production of secondary metabolites. High levels of heavy metal contamination in medicinal or other plants may suppress secondary metabolite production. Alternatively, the presence of heavy metals in medicinal plants may stimulate production of bioactive compounds in many plant species. Moreover, some research results suggest that heavy metals may play an important role in triggering plant genes to alter the titers or nature of secondary plant metabolites, although the exact mechanism by which this happens remains unclear. Oxidative stress induced by heavy metals triggers signaling pathways that affect production of specific plant metabolites. In particular, reactive oxygen species (ROS), generated during heavy metal stress, may cause lipid peroxidation that stimulates formation of highly active signaling compounds capable of triggering production of bioactive compounds (secondary metabolites) that enhances the medicinal value of the plant. As usual, further research is needed to clarify the mechanism by which heavy metals induce responses that result in enhanced secondary metabolite production.

Effects of cadmium on plant growth and physiological traits in contrast wheat recombinant inbred lines differing in cadmium tolerance

Four wheat (Triticum aestivum L.) lines differing in cadmium (Cd) tolerance previously identified from a recombinant inbred line population were subjected to 50 microM CdCl2 from the three-leaf stage for 24 d, to investigate the responses of wheat seedlings to Cd toxicity. Under Cd stress, most growth parameters and root morphological traits were reduced, except for secondary root numbers and average root diameter. Cd enhanced leaf cell peroxidation due to increased malondialdehyde (MDA) content and reduced activities of superoxide dismutase (SOD) and catalase (CAT) in leaves. In addition, CAT activity decreased in the Cd-sensitive lines while increased in the tolerant lines. Leaf photosystem II (PSII) was damaged, since the maximum efficiency of PSII photochemistry (Fv/Fm) and potential efficiency of PSII photochemistry under dark-adapted (Fv/Fo) decreased, while the initial fluorescence (Fo) increased in all lines under Cd stress. Then, total soluble sugar concentration decreased while free amino acids concentration increased in both shoot and root. We concluded that Cd-tolerant lines accumulated less Cd in plant and contained low Cd concentration in shoot (less translocation of Cd to shoot), maintained higher CAT activity in leaf and higher PS II function than the Cd-sensitive lines under Cd toxicity, thus could be related to their tolerant capacity to Cd in the present study.

Effect of cadmium accumulation on anti-inflammatory activity in two Eucomis species

Eucomis species (Hyacinthaceae) are widely used in South Africa as traditional medicine. The bulbs are used to alleviate a variety of symptoms including pain and inflammation. High levels of cyclooxygenase-1 and -2 (COX-1 and COX-2) inhibitory activity have been associated with certain Eucomis species. The aim of this study was to quantify cadmium(Cd) accumulation and examine its effect on COX-1 and COX-2 anti-inflammatory activity in Eucomis autumnalis and Eucomis humilis. Cadmium application at 2 mg L(-1) over a 6 week period revealed a substantial difference in total Cd accumulation in E. autumnalis and E. humilis (40.2 and 15.3 mg Cd kg-1, respectively). When supplied with Cd at 2 mg L(-1), E. humilis bulbous extracts showed lower inhibitory activity than the control for both COX-1 and COX-2. E. autumnalis bulbous extracts had greater COX-1 activity compared to the control. While COX-2 activity was suppressed. Researchers should be aware of the effect of environmental contaminants when reporting on biological activity of crude plant extracts.