Metal- and Organ-Specific Response to Heavy Metal-Induced Stress Mediated by Antioxidant Enzymes' Activities, Polyamines, and Plant Hormones Levels in Populus deltoides

Untargeted metabolic analysis using LC-Q-TOF-MS and toxicity assessment of Eryngium foetidum in zebrafish embryos

Toxicological studies of edible plant species are important to determine the safety of their consumption. Eryngium foetidum is an edible plant used in some countries for seasoning food and as a natural remedy in folk medicine. Despite this species' gastronomic and medicinal properties, the chemical composition and toxicity have been unclear. The objective of our investigation was to determine the toxic potential of E. foetidum in the zebrafish embryo model and identify the potential compounds involved in its toxicity by electrospray ionization liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry. Acute exposure of zebrafish embryos to n-hexane extract produced higher toxicity than the other extracts in a time- and concentration-dependent fashion (coagulated embryo). A 96-h median lethal concentration (LC 50) of 2.63 µg mL-1 (CI 95 % 0.58-28.5) was calculated by probit analysis. Caudal fin hypertrophy, head, yolk sac edema, caudal region, or somite malformations were observed. Secondary metabolites such as terpenes, polyphenols, and fatty acids were identified in the n-hexane extract. Also, pollutants such as diglycidyl resorcinol ether, diisopropyl adipate, and lauryl sulfate were found in the n-hexane extract. Our study revealed that chemical pollutants could be associated with the embryonic toxicity of the n-hexane extract of E. foetidum.

Alginate-Bentonite Encapsulation of Extremophillic Bacterial Consortia Enhances Chenopodium quinoa Tolerance to Metal Stress

This study explores the encapsulation in alginate/bentonite beads of two metal(loid)-resistant bacterial consortia (consortium A: Pseudomonas sp. and Bacillus sp.; consortium B: Pseudomonas sp. and Bacillus sp.) from the Atacama Desert (northern Chile) and Antarctica, and their influence on physiological traits of Chenopodium quinoa growing in metal(loid)-contaminated soils. The metal(loid) sorption capacity of the consortia was determined. Bacteria were encapsulated using ionic gelation and were inoculated in soil of C. quinoa. The morphological variables, photosynthetic pigments, and lipid peroxidation in plants were evaluated. Consortium A showed a significantly higher biosorption capacity than consortium B, especially for As and Cu. The highest viability of consortia was achieved with matrices A1 (3% alginate and 2% bentonite) and A3 (3% alginate, 2% bentonite and 2.5% LB medium) at a drying temperature of 25 °C and storage at 4 °C. After 12 months, the highest viability was detected using matrix A1 with a concentration of 106 CFU g-1. Further, a greenhouse experiment using these consortia in C. quinoa plants showed that, 90 days after inoculation, the morphological traits of both consortia improved. Chemical analysis of metal(loid) contents in the leaves indicated that consortium B reduced the absorption of Cu to 32.1 mg kg-1 and that of Mn to 171.9 mg kg-1. Encapsulation resulted in a significant increase in bacterial survival. This highlights the benefits of using encapsulated microbial consortia from extreme environments, stimulating the growth of C. quinoa, especially in soils with metal(loid) levels that can be a serious constraint for plant growth.

Spatio-temporal plant hormonomics: from tissue to subcellular resolution

Due to technological advances in mass spectrometry, significant progress has been achieved recently in plant hormone research. Nowadays, plant hormonomics is well established as a fully integrated scientific field focused on the analysis of phytohormones, mainly on their isolation, identification, and spatiotemporal quantification in plants. This review represents a comprehensive meta-study of the advances in the phytohormone analysis by mass spectrometry over the past decade. To address current trends and future perspectives, Web of Science data were systematically collected and key features such as mass spectrometry-based analyses were evaluated using multivariate data analysis methods. Our findings showed that plant hormonomics is currently divided into targeted and untargeted approaches. Both aim to miniaturize the sample, allowing high-resolution quantification to be covered in plant organs as well as subcellular compartments. Therefore, we can study plant hormone biosynthesis, metabolism, and signalling at a spatio-temporal resolution. Moreover, this trend has recently been accelerated by technological advances such as fluorescence-activated cell sorting or mass spectrometry imaging.

Ganoderma pfeifferi Bres. and Ganoderma resinaceum Boud. as Potential Therapeutic Agents: A Comparative Study on Antiproliferative and Lipid-Lowering Properties

Medicinal mushrooms, especially Ganoderma species, hold immense promise for the production of a wide range of bioactive compounds with various effects. The biochemical potential of indigenous fungal strains, specific to a region, could play a critical role in the continuous search for novel strains with superior activities on a global scale. This research focused on the ethanolic (EtOH) and hot-water (H2O) extracts of fruiting bodies of two wild-growing Ganoderma species: G. pfeifferi and G. resinaceum, with the aim of assessing their nutritional (total carbohydrate content-TCC) and mineral composition in relation to bioactive properties: antioxidant, antiproliferative and lipid-lowering. Atomic absorption spectrophotometry (AAS) revealed that G. pfeifferi is a promising source of minerals that are essential for numerous physiological functions in the human body like bone health and muscle and nerve function, with Ca (4.55 ± 0.41 mg/g d.w.) and Mg (1.33 ± 0.09 mg/g d.w.) being the most abundant macroelement present. Zn, Mn, and Cr were particularly notable, with concentrations ranging from 21.49 to 41.70 mg/kg d.w. The EtOH extract of G. pfeifferi demonstrated significantly elevated levels of TCC, essential macromolecules for energy and structural functions in the body, with higher quantities of all three standard carbohydrates detected in this type of extract. Similar to the revealed composition, the same species, G. pfeifferi, stood out as the most prominent antioxidant agent, with the H2O extract being stronger than EtOH in the ABTS assay (86.85 ± 0.67 mg TE/g d.w.), while the EtOH extract displayed the highest anti-OH• scavenging ability (IC50 = 0.18 ± 0.05 μg/mL) as well as the most notable reducing potential among all. The highest antiproliferative effect against the breast cancer cell line (MCF-7), were demonstrated by the H2O extracts from G. resinaceum with the most pronounced activity after 24 h (IC50 = 4.88 ± 0.50 μg/mL), which surpasses that of the standard compound, ellagic acid (IC50 = 33.94 ± 3.69 μg/mL). Administration of both Ganoderma extracts mitigated diabetic lipid disturbances and exhibited potential renal and hepatic protection in vivo on white Wistar rats by the preservation of kidney function parameters in G. resinaceum H2O pre-treatment (urea: 6.27 ± 0.64 mmol/L, creatinine: 50.00 ± 6.45 mmol/L) and the reduction in ALT levels (17.83 ± 3.25 U/L) compared to diabetic control groups treated with saline (urea: 46.98 ± 6.01 mmol/L, creatinine: 289.25 ± 73.87 mmol/L, and ALT: 60.17 ± 9.64 U/L). These results suggest that pre-treatment with G. resinaceum H2O extracts may have potential antidiabetic properties. In summary, detected microelements are vital for maintaining overall health, supporting metabolic processes, and protecting against various chronic diseases. Further research and dietary assessments could help determine the full potential and applications of the two underexplored Ganoderma species native to Serbia in nutrition and health supplements.

Polycyclic aromatic hydrocarbon (PAH) phytoaccumulation in urban areas by Platanus × acerifolia, Celtis australis, and Tilia grandifolia leaves and branches

Polycyclic aromatic hydrocarbon (PAH) concentrations in the leaves and 1-year-old branches of three common tree species growing in a middle-sized city located in a moderate climate zone were estimated. For this purpose, PAH phytoaccumulation in Platanus × acerifolia, Celtis australis, and Tilia grandifolia species from highly urbanized, traffic congested, and highly PAH-contaminated streets was compared with trees from non-contaminated parks in the same urban core. The gathered data was used to define 17 PAH profiles, identify the main PAH pollution emission sources, and determine the organ and species specificity of PAHs accumulation. Due to the direct absorption of polluted air via stomata, the leaves accumulated up to 30% more PAHs compared to the 1-year-old branches. As expected, PAH concentrations were much higher in street trees, while heavy weight PAHs (with five and six rings) were accumulated in the highest concentrations. The highest foliar Σ17 PAH concentrations were detected in street-grown C. australis, followed by P. acerifolia and T. grandifolia (502.68, 488.45, and 339.47 ng g-1 dry weight (DW), respectively). The same pattern was noted for Σ17 PAHs in branches (414.89, 327.58, and 342.99 ng g-1 DW, respectively). Thus, T. grandifolia emerged as the least effective PAH sink as it accumulated up to ~ 40% less PAHs than P. acerifolia and C. australis leaves/branches. Among the 17 tracked PAHs, benzo[a]anthracene, benzo[a]pyrene, dibenzo[a,h]anthracene, and pyrene were found to have accumulated in the highest concentrations in all analyzed species irrespective of the site, and accounted for more than 50% of the total detected PAHs. Finally, a "black box" about species and organ specificity, as well as specific drivers that limit PAHs uptake capacity by trees, was opened, while this work provides insights into further PAH phytoremediation strategies.

Variations in Proline Content, Polyamine Profiles, and Antioxidant Capacities among Different Provenances of European Beech (Fagus sylvatica L.)

International provenance trials are a hot topic in forestry, and in light of climate change, the search for more resilient beech provenances and their assisted migration is one of the challenges of climate-smart forestry. The main aim of the study was to determine intraspecific variability in European beech (Fagus sylvatica L.) among 11 beech provenances according to total antioxidant capacities estimated by various assays, such as DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid), FRAP (ferric reducing antioxidant power) assay, and radical scavenging capacity against nitric oxide (RSC-NO assays), as well as osmolyte content, primarily individual polyamines (putrescine, spermidine, and spermine), and free proline content. Polyamine amounts were quantified by using HPLC coupled with fluorescent detection after dansylation pretreatment. The highest values for radical scavenger capacity assays (ABTS, DPPH, and FRAP) were measured in the German provenances DE47 and DE49. Also, the highest NO inhibition capacity was found in the provenance DE49, while the highest content of proline (PRO), total phenolic content (TPC), and total flavonoid content (TFC) was recorded in DE47. The Austrian AT56 and German provenance DE49 were most abundant in total polyamines. This research underlines the importance of the application of common antioxidant assays as well as osmolyte quantification as a criterion for the selection of climate-ready beech provenances for sustainable forest management.

In vitro selection of drought-tolerant white poplar clones based on antioxidant activities and osmoprotectant content

Introduction

In light of upcoming climate change, there is an urgent requirement for tree improvement regarding adaptability to drought-caused stress and the development of quick and reliable screening methodologies for genotypes' drought tolerance. White poplar is, despite its high adaptability, considered to be an endangered tree species in Serbia, which gives it special importance in the preservation and improvement of biodiversity of riparian ecosystems. The main goal of this research was to evaluate the tolerance of five white poplar clones to the presence of polyethylene glycol (PEG 6000 molecular weight 6000) (different concentrations (e.g. 0 g/L, 1 g/L, 10 g/L, 20 g/L, and 50 g/L) in Aspen Culture Medium (ACM).

Methods

The tolerance of the clones was evaluated by using morphological parameters (shoot fresh and dry weight, root fresh and dry weight), photosynthetic pigments (contents of chlorophyll a, chlorophyll b, carotenoids, and chlorophyll a+b), and biochemical parameters (total phenolic content, total flavonoid content, ferric reducing antioxidant power, antioxidant activities (DPPH activity and ABTS assay), free proline content and glycine betaine content.

Results and Discussion

The values of morphological and photosynthetic pigments declined with an increase in the concentration of PEG 6000. At a concentration of 50 g/L, the content of shoot fresh mass decreased by 41%, the content of Chl a by 68%, Chl b by 65%, and Car by 76% compared to the control. Also, at the same medium, there was an increase in the content of total phenols, accumulation of proline, the content of glycine betaine as well as in antioxidant activity. Based on the obtained results, it can be assumed that more drought-tolerant clones are characterized by high values for biomass, high content of photosynthetic pigments, and high content of proline and glycine betaine in conditions similar to drought in vitro. Clone L-80 showed better results in most of the tested parameters, especially compared to the reference clone Villafranca.

Exogenous plant growth regulator and foliar fertilizers for phytoextraction of cadmium with Boehmeria nivea [L.] Gaudich from contaminated field soil

As a enrichment plant, ramie can be used for the phytoremediation of cadmium (Cd)-contaminated soil. However, it is worth exploring the role of plant growth regulators and foliar fertilizers in the process of plant growth and development and Cd adsorption. By measuring the agronomic traits, Cd content of aboveground and underground ramie, calculating the Cd transfer coefficient (TF) and Cd bioconcentration factors (BCF), and the correlation between various indicators. This study examined the effects of plant growth regulators and foliar fertilizers on ramie's capacity for Cd accumulation and transportation. Plant growth regulators and foliar fertilizers increased the Cd content of the aboveground ramie, reduced the Cd content of the underground ramie, and increased the TF. Among them, GA-1 increased the Cd content of the aboveground ramie to 3 times more than that of the control and reduced the Cd content of the underground ramie by 54.76%. Salicylic acid (SA) increased the Cd content of the aboveground ramie to three times more than that of the control. The combination of GA and foliar fertilizer reduced the Cd content of the aboveground and underground ramie and the TF and BCF of the underground ramie. After the hormones were sprayed, the TF of ramie had a significant positive correlation with the Cd content of the aboveground ramie; the BCF of the aboveground ramie had a significant positive correlation with the Cd content and TF of the aboveground ramie. The results indicate that Brassinolide (BR), gibberellin (GA), ethephon (ETH), polyamines (PAs), and salicylic acid (SA) have different effects on the enrichment and transport of Cd in ramie. This study provided an effective method to improve the capacity for ramie to adsorb heavy metals during cultivation.

Advances in Forest Ecophysiology: Stress Response and Ecophysiological Indicators of Tree Vitality

Back in the beginning of the year 2021, when the work on this Special Issue started, it was quite clear that the topics of tree stress response and the ecophysiological indicators of tree vitality were both current and important, but the attitude of the scientific community towards the idea of a Special Issue on the subject was yet to be determined [...].