Microalgae are widely used as representative primary producers in ecotoxicology, while macrophytes are much less studied. Here we compared the bioavailability and cellular toxicity pathways of 2 h-exposure to 10−6 mol L−1 Cu in the macrophyte Elodea nuttallii and the green microalga Chlamydomonas reinhardtii.Uptake rate was similar but faster in the algae than in the macrophyte, while RNA-Sequencing revealed a similar number of regulated genes. Early-regulated genes were congruent with expected adverse outcome pathways for Cu with Gene Ontology terms including gene regulation, energy metabolism, transport, cell processes, stress, antioxidant metabolism and development. However, the gene regulation level was higher in E. nuttallii than in C. reinhardtii and several categories were more represented in the macrophyte than in the microalga. Moreover, several categories including oxidative pentose phosphate pathway (OPP), nitrate metabolism and metal handling were only found for E. nuttallii, whereas categories such as cell motility, polyamine metabolism, mitochondrial electron transport and tricarboxylic acid cycle (TCA) were unique to C. reinhardtii. These differences were attributed to morphological and metabolic differences and highlighted dissimilarities between a sessile and a mobile species. Our results highlight the efficiency of transcriptomics to assess early molecular responses in biota, and the importance of studying more aquatic plants for a better understanding on the impact and fate of environmental contaminants.

Three ex situ collections of poplar clones from natural populations of Populus alba and P. nigra growing in northern Italy were assessed for their genetic dissimilarity (GD) by means of amplified fragment length polymorphism (AFLP). The high GD evidenced within populations was exploited for screening 168 clones in a field trial on heavy metal-polluted soil. After one growth season, clonal differences in plant survival and growth were observed. On the basis of performance, six clones were singled out, and used to evaluate copper and zinc accumulation in different organs. Clonal differences in metal concentrations were most evident for leaves and stems; one clone of P. alba (AL35) had a distinctly higher concentration of both metals in the roots. Leaf polyamine (putrescine, spermidine, spermine) profiles correlated with tissue metal concentrations, depending on the clone, plant organ and metal. In particular, the high metal-accumulating clone AL35 exhibited a dramatically higher concentration of free and conjugated putrescine. Overall, the results indicate that, given the high GD of Populus even within populations, it is possible to identify genotypes best suited for soil clean-up, and useful also for investigating physiological markers associated with high metal accumulation/tolerance High survival rate and heavy metal accumulation are associated with high polyamine concentration in an elite poplar clone.

Plant height is among the most important agronomic traits influencing crop yield. Wheat lines carrying Rht genes are important in plant breeding due to their both higher yield capacity and better tolerance to certain environmental stresses. However, the effects of dwarf-inducing genes on stress acclimation mechanisms are still poorly understood. Under the present conditions, cadmium stress induced different stress responses and defence mechanisms in the wild-type and dwarf mutant, and the mutant with the Rht-B1c allele exhibited higher tolerance. In the wild type after cadmium treatment, the abscisic acid synthesis increased in the leaves, which in turn might have induced the polyamine and proline metabolisms in the roots. However, in the mutant line, the slight increment in the leaf abscisic acid content accompanied by relatively high salicylic acid accumulation was not sufficient to induce such a great accumulation of proline and putrescine. Although changes in proline and polyamines, especially putrescine, showed similar patterns, the accumulation of these compounds was antagonistically related to the phytochelatin synthesis in the roots of the wild type after cadmium stress. In the dwarf genotype, a favourable metabolic shift from the synthesis of polyamine and proline to that of phytochelatin was responsible for the higher cadmium tolerance observed.

Metals are significant environmental pollutants, and their toxicity is a problem for all living organisms. Indeed, aquatic plants are particularly sensitive to the excess of metal ions. Several researches report that aquatic plants exposed to metal-induced toxicity showed similar responses (e.g. inhibition of growth and induction of oxidative stress). Meanwhile, many studies were involved to counter these toxicities. This paper provides a brief review of the role of the exogenous supply of some compounds in the alleviation or reduction of toxicity in aquatic plants generated by metals. Particular attention is given to the role of polyamine, proline, nitric oxide, glutathione and phytochelatin.

Biotic and abiotic stresses, especially heavy metal toxicity, are becoming a big problem in agriculture, which pose serious threats to crop production. Plant hormones have recently been used to develop stress tolerance in a variety of plants. Brassinosteroids (BRs) are the sixth class of plant steroid hormones, with pleiotropic effects on plants. Exogenous application of BRs to boost plant tolerance mechanisms to various stresses has been a major research focus. Numerous studies have revealed the role of these steroidal hormones in the up-regulation of stress-related resistance genes, as well as their interactions with other metabolic pathways. BRs interact with other phytohormones such as auxin, cytokinin, ethylene, gibberellin, jasmonic acid, abscisic acid, salicylic acid, and polyamines to regulate a variety of physiological and developmental processes in plants. BRs regulate expressions of many BR-inducible genes by activating the brassinazole-resistant 1 (BZR1)/BRI1-EMS suppressor 1 (BES1) complex. Moreover, to improve plant development under a variety of stresses, BRs regulate antioxidant enzyme activity, chlorophyll concentration, photosynthetic capability, and glucose metabolism. This review will provide insights into the mechanistic role and actions of brassinosteroids in plants in response to various stresses.

As soil contamination with heavy metals is increasing and polyamines have roles in the growth of mycorrhiza and plants, it is important to study phytoremediation, growth, tolerance, and mycorrhization in Lallemantia iberica as a multi-purpose plant, by the application of putrescine along with mycorrhiza in Pb-contaminated soils. For this purpose, the study was performed in a factorial arrangement with Pb (0, 300, 600, and 900 mg Pb/kg soil), mycorrhiza (non-inoculation, Funneliformis mosseae (Fm), and Rhizophagus intraradices (Ri)), and putrescine (0, 0.5, and 1 mM) in a greenhouse. Results showed that antioxidant activities, plant Pb, and mycorrhizal features enhanced, while transfer factor (TF), biomass, and tolerance decreased under Pb levels. Mycorrhiza improved growth, greenness, defense, and tolerance and reduced TF, Pb, and H₂O₂ content under Pb stress. Putrescine (0.5 mM) increased catalase activity, biomass, and colonization and reduced Pb content and TF under Pb levels. Combination of 0.5 mM putrescine with Fm increased shoot biomass (13%), peroxidase (17.2%), root P (7.5%), shoot tolerance (14.4%), colonization (5.1%), and hyphal width (5.5%) and decreased malondialdehyde (20.5%) and shoot Pb content (28.1%). Putrescine (1 mM) had negative effects on all traits in combination with Ri but not with Fm. Combination of putrescine and Fm showed more efficiency in decreasing Pb content in L. iberica and was effective in phytostabilization. It is generally concluded that 0.5 mM putrescine was the beneficial concentration in combination with mycorrhiza, Pb stress, and single use to improve plant performance, and Fm was a useful species for improving the growth and tolerance of L. iberica under Pb levels.

Adsorption of Rh(III) ions from the aqueous phase containing chloride ions was investigated batchwise using 1,3,5-triazine pentaethylenehexamine (TAPEHA) resin, which is highly resistant to strong acidic conditions. The effects of pH, temperature, initial concentration, and contact time on adsorption were examined. Rh(III) adsorption is favorable from the aqueous phase containing 3.0 and 0.1 M HCl. In both acidic cases, Langmuir is best fitting isotherm equation to system. The kinetics of Rh(III) adsorption on TAPEHA polymer was found to obey the pseudo-second-order kinetic equation, at both cases. Langmuir monolayer adsorption capacities were calculated as 327.03 and 113.76 mg/g in 3.0 and 0.1 M HCl, respectively. Experimental maximum adsorption capacities were measured as 198 and 100 mg/g in 3.0 and 0.1 M HCl, respectively. Due to different Rh(III) complexes with chlorine depending on acid concentrations, adsorption of Rh(III) from solutions containing 3.0 and 0.1 M HCl occurred via two different mechanisms; namely, ion exchange and surface complexation. The reuse of TAPEHA was also studied by column procedure, and the adsorption capacity of TAPEHA was not changed by using it five times. Adsorbed Rh(III) ions onto TAPEHA were completely eluted with thiourea 3% (w/v) in 1.0 M HCl. These findings showed that TAPEHA has a high resistance to acidic solutions and a higher Rh(III) uptake capacity than commercial adsorbents. Hence it can be used for rhodium recycling.

Vapour-liquid equilibrium (VLE) of CO₂ in aqueous dipropylenetriamine (DPTA) is investigated experimentally using a stirred equilibrium cell setup. Equilibrium solubility of CO₂ is measured in the temperature and pressure range of (313–333) K and (1–100) kPa respectively. Composition of aqueous DPTA solvent used for the absorption study is in the range of (5–15) mass%. Experimental data shows higher CO₂ loading capacity of this solvent compared to conventional solvents like monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), and N-methyldiethanolamine (MDEA) as well as recently developed polyamine solvents like aminoethylethanolamine (AEEA), piperazine (PZ), and hexamethylenediamine (HMDA). Experimental VLE data is then correlated using the electrolyte non-random two-liquid (e-NRTL) theory which is an activity coefficient–based model for the electrolyte system. Data regression system (DRS) in Aspen Plus® (V8.8) is employed to fit the e-NRTL model equation with the experimental data by regressing the model parameters. Model-predicted data is found to be in good agreement with the experimental VLE data with an average absolute deviation of 22.3%. Performance of aqueous DPTA solvent is also analysed by predicting solvent capacity, equilibrium liquid-phase speciation, and heat of CO₂ absorption using the newly developed e-NRTL model for the investigated system.