Transcriptomic response of Arabidopsis thaliana (L.) Heynh. roots to ibuprofen

The function of UDP-glycosyltransferases in plants and their possible use in crop protection

Glycosyltransferases catalyse the transfer of a glycosyl moiety from a donor to an acceptor. Members of this enzyme class are ubiquitous throughout all kingdoms of life and are involved in the biosynthesis of countless types of glycosides. Family 1 glycosyltransferases, also referred to as uridine diphosphate-dependent glycosyltransferases (UGTs), glycosylate small molecules such as secondary metabolites and xenobiotics. In plants, UGTs are recognised for their multiple functionalities ranging from roles in growth regulation and development, in protection against pathogens and abiotic stresses and in adaptation to changing environments. In this study, we review UGT-mediated glycosylation of phytohormones, endogenous secondary metabolites, and xenobiotics and contextualise the role this chemical modification plays in the response to biotic and abiotic stresses and plant fitness. Here, the potential advantages and drawbacks of altering the expression patterns of specific UGTs along with the heterologous expression of UGTs across plant species to improve stress tolerance in plants are discussed. We conclude that UGT-based genetic modification of plants could potentially enhance agricultural efficiency and take part in controlling the biological activity of xenobiotics in bioremediation strategies. However, more knowledge of the intricate interplay between UGTs in plants is needed to unlock the full potential of UGTs in crop resistance.

Specific glutathione-S-transferases ensure an efficient detoxification of diclofenac in Solanum lycopersicum L. plants

Diclofenac (DCF) is a very common pharmaceutical that, due to its high use and low removal rate, is considered a prominent contaminant in surface and groundwater worldwide. In this study, Solanum lycopersicum L. cv. Micro-Tom (tomato) was used to disclose the role of glutathione (GSH)-related enzymes, as GSH conjugation with DCF is a well reported detoxification mechanism in mammals and some plant species. To achieve this, S. lycopersicum plants were exposed to 0.5 and 5 mg L^-1 of DCF for 5 weeks under a semi-hydroponic experiment. The results here obtained point towards an efficient DCF detoxification mechanism that prevents DCF bioaccumulation in fruits, minimizing any concerns for human health. Although a systemic response seems to be present in response to DCF, the current data also shows that its detoxification is mostly a root-specific process. Furthermore, it appears that GSH-mediated DCF detoxification is the main mechanism activated, as glutathione-S-transferase (GST) activity was greatly enhanced in roots of tomato plants treated with 5 mg L^-1 DCF, accompanied by increased glutathione reductase activity, responsible for GSH regeneration. By applying a targeted gene expression analysis, we provide evidence, for the first time, that SlGSTF4 and SlGSTF5 genes, coding for GSTs from phi class, were the main players driving the conjugation of this contaminant. In this sense, and even though tomato plants appear to be somewhat tolerant to DCF exposure, research on GST activity can prove to be instrumental in remediating DCF-contaminated environments and improving plant growth under such conditions.

Stress symptoms and plant hormone-modulated defense response induced by the uptake of carbamazepine and ibuprofen in Malabar spinach (Basella alba L.)

Due to their wide applications and extensive discharges, pharmaceuticals have recently become a potential risk to aquatic and terrestrial organisms. The uptake of pharmaceuticals have been shown to stimulate plant defense systems and induce phytotoxic effects. Signaling molecules such as plant hormones play crucial roles in plant stress and defense responses, but the relationship between these molecules and pharmaceutical uptake has rarely been investigated. In this study, two common pharmaceuticals, carbamazepine and ibuprofen, and three stress-related plant hormones, jasmonic acid, salicylic acid, and abscisic acid, were simultaneously tracked in the roots and stems of Malabar spinach (Basella alba L.) via an in vivo solid phase microextraction (SPME) method. We also monitored stress-related physiological markers and enzymatic activities to demonstrate plant hormone modulation. The results indicate that pharmaceutical uptake, subsequent stress symptoms, and the defense response were all significantly correlated with the upregulation of plant hormones. Moreover, the plant hormones in the exposure group failed to recover to normal levels, indicating that plants containing pharmaceutical residues might be subject to potential risks.

Metabolism of non-steroidal anti-inflammatory drugs by non-target wild-living organisms

The presence of the non-steroidal anti-inflammatory drugs (NSAIDs) in the environment is a fact, and aquatic and soil organisms are chronically exposed to trace levels of these emerging pollutants. This review presents the current state of knowledge on the metabolic pathways of NSAIDs in organisms at various levels of biological organisation. More than 150 publications dealing with target or non-target analysis of selected NSAIDs (mainly diclofenac, ibuprofen, and naproxen) were collected. The metabolites of phase I and phase II are presented. The similarity of NSAIDs metabolism to that in mammals was observed in bacteria, microalgae, fungi, higher plants, invertebrates, and vertebrates. The differences, such as newly detected metabolites, the extracellular metabolism observed in bacteria and fungi, or phase III metabolism in plants, are highlighted. Metabolites detected in plants (conjugates with sugars and amino acids) but not found in any other organisms are described. Selected, in-depth studies with isolated bacterial strains showed the possibility of transforming NSAIDs into assimilable carbon sources. It has been found that some of the metabolites show higher toxicity than their parent forms. The presence of metabolites of NSAIDs in the environment is the cumulative effect of their introduction with wastewaters, their formation in wastewater treatment plants, and their transformation by non-target wild-living organisms.

Transcriptomic response of Arabidopsis thaliana roots to naproxen and praziquantel

Exposition to pharmaceutical compounds released to the environment is considered as a potential risk for various organisms. We exposed Arabidopsis thaliana plants to naproxen (NAP) and praziquantel (PZQ) in 5 µM concentration for 2 days and recorded transcriptomic response in their roots with the aim to estimate ecotoxicity and to identify gene candidates potentially involved in metabolism of both compounds. Nonsteroidal anti-inflammatory drug NAP up-regulated 105 and down-regulated 29 genes (p-value ≤ 0.1, fold change ≥ 2), while anthelmintic PZQ up-regulated 389 and down-regulated 353 genes with more rigorous p-value ≤ 0.001 (fold change ≥ 2). High number of up-regulated genes coding for heat shock proteins and other genes involved in response to biotic and abiotic stresses as well as down-regulation of genes involved in processes such as cell proliferation, transcription and water transport indicates serious negative effect of PZQ. NAP up-regulated mostly genes involved in various biological processes and signal transduction and down-regulated mainly genes involved in signal transduction and electron transport or energy pathways. Further, two cytochrome P450s (demethylation) and one methyltransferase (methylation of carboxyl group) were identified as candidates for phase I and several glutathione- and glycosyltransferases (conjugation) for phase II of NAP metabolism. Cytochrome P450s, glutathione and glycosyltransferases seem to play role also in metabolism of PZQ. Up-regulation of several ABC and MATE transporters by NAP and PZQ indicated their role in transport of both compounds.

Cytokinin at the Crossroads of Abiotic Stress Signalling Pathways

Cytokinin is a multifaceted plant hormone that plays major roles not only in diverse plant growth and development processes, but also stress responses. We summarize knowledge of the roles of its metabolism, transport, and signalling in responses to changes in levels of both macronutrients (nitrogen, phosphorus, potassium, sulphur) and micronutrients (boron, iron, silicon, selenium). We comment on cytokinin's effects on plants' xenobiotic resistance, and its interactions with light, temperature, drought, and salinity signals. Further, we have compiled a list of abiotic stress-related genes and demonstrate that their expression patterns overlap with those of cytokinin metabolism and signalling genes.