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Nickel release from anthropogenic and natural sources into the environment has resulted in biomagnification in terrestrial ecosystems. Here, we studied the biotransfer and toxicokinetics of nickel (Ni) along the soil < faba bean < aphid-ladybird food chain. The soil was spiked with the following Ni concentrations (in mg kg−1 soil ww); T0 (0), T1 (25), T2 (50), T3 (75), and T4 (100). Our results revealed a significant elevation of Ni transfer with increasing Ni doses. The transfer coefficients (TC) indicate Ni biomagnified in soil to root and shoot to aphid >1 while the TC of the biominimisation of Ni in the aphid to ladybird was

Ammonia and ammonium have received less attention than other forms of air pollution, with limited progress in controlling emissions at UK, European and global scales. By contrast, these compounds have been of significant past interest to science and society, the recollection of which can inform future strategies. Sal ammoniac ( nūshādir , nao sha ) is found to have been extremely valuable in long-distance trade ( ca AD 600–1150) from Egypt and China, where 6–8 kg N could purchase a human life, while air pollution associated with nūshādir collection was attributed to this nitrogen form. Ammonia was one of the keys to alchemy—seen as an early experimental mesocosm to understand the world—and later became of interest as ‘alkaline air’ within the eighteenth century development of pneumatic chemistry. The same economic, chemical and environmental properties are found to make ammonia and ammonium of huge relevance today. Successful control of acidifying SO 2 and NO x emissions leaves atmospheric NH 3 in excess in many areas, contributing to particulate matter (PM 2.5 ) formation, while leading to a new significance of alkaline air, with adverse impacts on natural ecosystems. Investigations of epiphytic lichens and bog ecosystems show how the alkalinity effect of NH 3 may explain its having three to five times the adverse effect of ammonium and nitrate, respectively. It is concluded that future air pollution policy should no longer neglect ammonia. Progress is likely to be mobilized by emphasizing the lost economic value of global N emissions ($200 billion yr −1 ), as part of developing the circular economy for sustainable nitrogen management. This article is part of a discussion meeting issue ‘Air quality, past present and future’.

The study aims at investigating the efficacy of individual as well as combined application of AM fungi (Glomus macrocarpum) and ZnO nanoparticles on the uptake of lead and its toxicity in wheat (Triticum aestivum L.). The plants were grown in pots with different treatments of AM Fungi, ZnO NP, and Pb. The individual applications of AM fungi (Glomus macrocarpum) and ZnO NPs increased the growth and biochemical attributes of wheat and decreased the Pb uptake under Pb stress. The combined application of AM fungi (Glomus macrocarpum) and ZnO nanoparticles synergistically enhanced the overall growth performance of the plant and significantly reduced the uptake of Pb in wheat grown in Pb spiked soils. The combined application was effective, with 30.66 % increase in plant height, 30.62 % increase in plant fresh weight, 54.26 % increase in plant dry weight, 45.45 % increase in total chlorophyll content, 19.59 % increase in proline content, 26.65 % higher activity of SOD, 15.12 % higher activity of catalase (CAT), 17.69 % increase in H2O2 content, 17.69 % increase in lipid peroxidation content, 52.09 % and 58.19 % decrease in Pb concentration in root and shoot of wheat, respectively, grown in Pb spiked soil (100 mg kg−1 soil). The results indicate that combined application of AM fungi and ZnO nanoparticles can be a promising technique for the utilization of Pb-contaminated soils.

Rice is a staple food of more than half of the world’s population; more than 3.5 billion inhabitants depend on rice for obtaining 20% of their daily calorie intake. Nitrogen is the most important for crop growth and yield potential. Indeed, nitrogen is essential to stimulate tillering, leaf growth, photosynthesis, and protein synthesis. Significant achievements have recently been observed at the molecular level in nitrogen use efficiency and water use efficiency in plants. In this chapter we will discuss the following issue: (i) definition of both nitrogen use efficiency and water use efficiency, (ii) genes responsible for nitrogen use efficiency and water use efficiency, (iii) best ways for improving water and nutrient use efficiency in rice, and (iv) optimizing nitrogen options for improving water and nitrogen use efficiency of rice under different water regimes.

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The present study investigates the extent of biotransfer and bioaccumulation of cadmium (Cd), lead (Pb) and zinc (Zn) from fly ash amended soil in mustard (Brassica juncea)-aphid (Lipaphis erysimi)-beetle (Coccinella septempunctata) food chain and its subsequent implications for the beetle. The soil was amended with fly ash at the rates of 0, 5, 10, 20 and 40% (w/w). Our results showed that the uptake of Cd, Pb and Zn from soil to mustard root increased with the increase in fly ash application rates, but their root to shoot translocation was relatively restricted. Increase in chlorophyll content and dry mass of mustard plant on treatments ≥20% even at elevated accumulation of Cd (1.67mgkg(-1)), Pb (18.25mgkg(-1)) and Zn (74.45mgkg(-1) dry weight) in its shoot showed relatively higher tolerance of selected mustard cultivar to heavy metal stress. The transfer coefficient (TC(1)) of Cd from mustard shoot to aphid was always >1, indicating that Cd biomagnified in aphids at second trophic level. But, there was no biomagnification of Cd in adult beetles at third trophic level. Zinc accumulation was 2.06 to 2.40 times more in aphids than their corresponding host shoots and 1.26-1.35 times more in adult beetles than their prey (aphids) on which they fed. Lead was only metal whose TC was 0.05) biomass and predation rate of predatory beetles indicated that all levels of soil amendments with fly ash did not have any lethal or sub-lethal effects on beetles.

Abiotic stress is currently being realized as one of the most ubiquitous and potential threats to human existence resulting in the overwhelming consequences to our health as well as agricultural systems. Jasmonates (JAs), imperative signaling compounds and derivatives of fatty acid metabolism, play a substantial role in mediating a variety of defense responses in plants to overcome different types of stresses. Jasmonates, oxylipin compounds ubiquitous in the plant kingdom, besides regulating different aspects of plant growth and development, evoke and modulate several plant processes by involving diverse crosstalk signaling mechanisms with different hormones and nutrient elements under perturbed environmental conditions. Methyl jasmonate (MeJA) acts as a signaling molecule that is perceived by protein receptors involved in the stress responses leading to the induction of signal transduction cascades and activating different antioxidant proteins. The present chapter is aimed at covering (1) the biosynthesis of jasmonates in plants; (2) different roles that MeJa plays under salt stress; (3) signal transduction cascades underlying the stress induced tolerance; (4) brief highlights of future prospects.

Plant phenolics or polyphenols, the aromatic compounds with one or more hydroxyl groups, are produced by plants mainly for protection against stresses. Phenolics are secondary natural metabolites emerging from the shikimate/phenylpropanoid pathway or polyketide acetate/malonate pathway, producing monomeric and polymeric phenols and polyphenols, which participate in a wide range of physiological activities in plants. Plants are known to have synthesized thousands of different phenolic compounds throughout the course of evolution to cope with constantly changing environments. Plants accumulate phenolic compounds in their tissues as an adaptive response to adverse environmental conditions and have a key role in the regulation of various environmental stresses, such as high light, low temperatures, pathogen infection, herbivores, and nutrient deficiency. This chapter details the biosynthesis, role, and regulation of plant phenolics in response to various abiotic stresses.

Lead (Pb) contamination of agroecosystems is a serious issue as Pb is a persistent pollutant that is retained in soil for long, causing toxicities to organisms. This study examines biotransfer of Pb from soils treated with different concentrations of Pb through a broad bean (Vicia faba L.)–aphid (Aphis fabae Scop.)–ladybird (Coccinella transversalis Fabricius) food chain and its consequent inference for natural biological control, the ladybird. The soil was amended with Pb at the rates of 0, 25, 50, 75 and 100 mg kg−1 (w/w). The amount of Pb in plant, aphid and ladybird increased in a dose-dependent manner to Pb contents in the soil. The results showed that Pb biomagnified from soil to root with transfer coefficient always > 1. Biominimization of Pb occurred at the second trophic level in aphids and at the third trophic level in ladybirds as their respective transfer coefficients from shoot to aphid and aphid to ladybird were always

Several members of Brassicaceae family are well known metal accumulators. High metal translocation from their roots to above ground shoots without showing any phytotoxic symptoms make them potential candidates for remediation of various metal/metalloid contaminated areas. These plants tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles of aboveground parts especially leaves. This is partly done by overexpression of specific metal transporters in different tissues from metal uptake in the root and shoot up to the storage sites (non sensitive) in the leaf. Hyperaccumulation and hypertolerance traits associated with Brassicaceae ignited interests in scientific community to understand and investigate the range of mechanisms and omics in these plants with relation to accumulation of metals and their detoxification. In this chapter we will try to discuss the mechanism of heavy metal uptake in Brassicaceae and their tolerance and detoxification pathways in these plants.

The contamination of agroecosystems due to the presence of trace elements in commonly used agricultural materials is a serious issue. The most contaminated material is usually sewage sludge, and the sustainable use of this material within agriculture is a major concern. This study addresses a key issue in this respect, the fate of trace metals applied to soil in food chains. The work particularly addresses the transfer of Pb, which is an understudied element in this respect, and compares the transfer of Pb with two of the most labile metals, Cd and Zn. The transfer of these elements was determined from sludge-amended soils in a food chain consisting of Indian mustard (Brassica juncea), the mustard aphid (Lipaphis erysimi) and a predatory beetle (Coccinella septempunctata). The soil was amended with sludge at rates of 0, 5, 10 and 20 % (w/w). Results showed that Cd was readily transferred through the food chain until the predator trophic level. Zn was the most readily transferred element in the lower trophic levels, but transfer to aphids was effectively restricted by the plant regulating shoot concentration. Pb had the lowest level of transfer from soil to shoot and exhibited particular retention in the roots. Nevertheless, Pb concentrations were significantly increased by sludge amendment in aphids, and Pb was increasingly transferred to ladybirds as levels increased. The potential for Pb to cause secondary toxicity to organisms in higher trophic levels may have therefore been underestimated.

Insights into the alterations of the mammalian genome in neoplastic diseases and the mechanism of action of the therapeutic anticancer drugs are one of the extremely important, diverse, and challenging areas of study currently. By the virtue of lingering toxicity of the reputable chemical drugs, plant-derived anticancer substances, viz., vinblastine, vincristine, Taxol, topotecan, camptothecin, and podophyllotoxin derivatives, are highly safe and efficient in the treatment and management of this monstrous disease. Among the list of accessible targets of the therapeutic drugs, DNA replication and mitosis, hormonal regulation of cell growth, aberrant signaling pathways, cell surface receptors, and second messengers are noteworthy. Nowadays, newer therapeutic approaches are being followed, and an increased understanding into the mechanism of action of the therapeutic anticancer agents is evolving due to continuous and relentless efforts of the researchers. The aim of the present chapter is to highlight the application of medicinal plants and their secondary metabolites as anticancer substances and also focus on the signaling aspects of potential anticancer compounds to find out their mechanisms of action against cancer cells.

Plants are subjected to various kinds of abiotic stresses throughout their life cycles which include salinity, drought, temperature (heat and cold), heavy metal, nutrient deficiency and UV radiation. Such types of stresses in plants lead the overproduction of certain chemical entities known as reactive oxygen species (ROS) which are highly reactive and cause damage to proteins, lipids, carbohydrates and macromolecules. The ROS include hydrogen peroxide (H2O2), superoxide radical (O2•−), hydroxyl radical (OH•), perhydroxyl radical (HO2 •), etc. But, nature has gifted the plants with very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaiacol peroxidase, GOPX; and glutathione-S-transferase, GST) and non-enzymatic (ascorbic acid, AA; glutathione, GSH; tocopherols; flavonoids; proline; etc.) antioxidant defence systems which work in coordination to detoxify and protect plant cells from oxidative damage. Moreover, ROS play a role as secondary messenger which induces cell to undergo programmed cell death.

Proline accumulation occurs in a wide range of plant species in response to various kinds of environmental stresses. A large body of evidence suggests that a positive correlation occurs between proline accumulation and plant stress tolerance. In this chapter, we will discuss the metabolism of proline accumulation and its role in stress tolerance in plants. Existing literature indicates that despite acting as an osmolyte, proline also plays important roles during stress as a metal chelator and an antioxidative defence molecule. Moreover, when applied exogenously at low concentrations, proline enhanced stress tolerance in plants. However, some reports point out adverse effects of proline when applied at higher doses. Role of proline in seed germination, flowering and other developmental programmes is also presented in this chapter.

Heavy metals and metalloids in trace amounts are natural components of environment. Their excessive addition by anthropogenic means posed a serious threat to the stability of ecosystem. Recent concerns of environmental contamination have initiated the development of appropriate technologies for removing or reducing such toxicants from different components of environment. Plants that accumulate greater than 0.1 % metals in leaves or other tissues without showing any visible toxicity symptoms are categorised as hyperaccumulators. These plants may be used as cost-effective and eco-friendly remediators at contaminated sites. In the present review, the key roles of several species of family Brassicaceae have been highlighted with species-level mechanism of phytoremediation. About (25 %) members of the Brassicaceae comprising of about 90 species are metal hyperaccumulators discovered worldwide to date. These Brassicaceae members are potential candidates for phytoremediation technologies. Of these 90 metal hyperaccumulators, species of the genera such as Alyssum, Arabidopsis, Noccaea and Brassica have been studied extensively for their ability to hyperaccumulate, remove, destroy, degrade, sequester, transform, assimilate, metabolise or detoxify majority of trace metals and appear to be model phytoremediators. These species are also attractive candidates for developing transgenics by introducing relevant genes to improve their applicability for phytoremediation. In this review, we elucidate the diversity and role of some of the Brassicaceae members in remediating contaminated sites worldwide and also highlighted the physiological mechanisms of uptake and tolerance, the genetic basis for the metal tolerance mechanisms.