Role of proline under changing environments: a review

Insight into the plant-associated bacterial interactions: Role for plant arsenic extraction and carbon fixation

This study investigated the interactions between rhizosphere and endosphere bacteria during phytoextraction and how the interactions affect arsenic (As) extraction and carbon (C) fixation of plants. Pot experiments, high-throughput sequencing, metabonomics, and network analysis were integrated. Results showed that positive correlations dominated the interconnections within modules (>95 %), among modules (100 %), and among keystone taxa (>72 %) in the bacterial networks of plant rhizosphere, root endosphere, and shoot endosphere. This confirmed that cooperative interactions occurred between bacteria in the rhizosphere and endosphere during phytoextraction. Modules and keystone taxa positively correlating with plant As extraction and C fixation were identified, indicating that modules and keystone taxa promoted plant As extraction and C fixation simultaneously. This is mainly because modules and keystone taxa in plant rhizosphere, root endosphere, and shoot endosphere carried arsenate reduction and C fixation genes. Meanwhile, they up-regulated the significant metabolites related to plant As tolerance. Additionally, shoot C fixation increased peroxidase activity and biomass thereby facilitating plant As extraction was confirmed. This study revealed the mechanisms of plant-associated bacterial interactions contributing to plant As extraction and C fixation. More importantly, this study provided a new angle of view that phytoextraction can be applied to achieve multiple environmental goals, such as simultaneous soil remediation and C neutrality.

Exogenous Hydrogen Sulfide Supplementation Alleviates the Salinity-Stress-Mediated Growth Decline in Wheat (Triticum aestivum L.) by Modulating Tolerance Mechanisms

The impact of the exogenous supplementation of hydrogen sulfide (20 and 50 µM HS) on growth, enzyme activity, chlorophyll pigments, and tolerance mechanisms was studied in salinity-stressed (100 mM NaCl) wheat. Salinity significantly reduced height, fresh and dry weight, chlorophyll, and carotenoids. However, the supplementation of HS (at both concentrations) increased these attributes and also mitigated the decline to a considerable extent. The exogenous supplementation of HS reduced the accumulation of hydrogen peroxide (H2O2) and methylglyoxal (MG), thereby reducing lipid peroxidation and increasing the membrane stability index (MSI). Salinity stress increased H2O2, MG, and lipid peroxidation while reducing the MSI. The activity of nitrate reductase was reduced due to NaCl. However, the supplementation of HS alleviated the decline with obvious effects being seen due to 50 µM HS. The activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) was assayed and the content of reduced glutathione (GSH) increased due to salt stress and the supplementation of HS further enhanced their activity. A decline in ascorbic acid due to salinity stress was alleviated due to HS treatment. HS treatment increased the endogenous concentration of HS and nitric oxide (NO) under normal conditions. However, under salinity stress, HS supplementation resulted in a reduction in HS and NO as compared to NaCl-treated plants. In addition, proline and glycine betaine increased due to HS supplementation. HS treatment reduced sodium levels, while the increase in potassium justified the beneficial role of applied HS in improving salt tolerance in wheat.

Microbial Exudates as Biostimulants: Role in Plant Growth Promotion and Stress Mitigation

Microbes hold immense potential, based on the fact that they are widely acknowledged for their role in mitigating the detrimental impacts of chemical fertilizers and pesticides, which were extensively employed during the Green Revolution era. The consequence of this extensive use has been the degradation of agricultural land, soil health and fertility deterioration, and a decline in crop quality. Despite the existence of environmentally friendly and sustainable alternatives, microbial bioinoculants encounter numerous challenges in real-world agricultural settings. These challenges include harsh environmental conditions like unfavorable soil pH, temperature extremes, and nutrient imbalances, as well as stiff competition with native microbial species and host plant specificity. Moreover, obstacles spanning from large-scale production to commercialization persist. Therefore, substantial efforts are underway to identify superior solutions that can foster a sustainable and eco-conscious agricultural system. In this context, attention has shifted towards the utilization of cell-free microbial exudates as opposed to traditional microbial inoculants. Microbial exudates refer to the diverse array of cellular metabolites secreted by microbial cells. These metabolites enclose a wide range of chemical compounds, including sugars, organic acids, amino acids, peptides, siderophores, volatiles, and more. The composition and function of these compounds in exudates can vary considerably, depending on the specific microbial strains and prevailing environmental conditions. Remarkably, they possess the capability to modulate and influence various plant physiological processes, thereby inducing tolerance to both biotic and abiotic stresses. Furthermore, these exudates facilitate plant growth and aid in the remediation of environmental pollutants such as chemicals and heavy metals in agroecosystems. Much like live microbes, when applied, these exudates actively participate in the phyllosphere and rhizosphere, engaging in continuous interactions with plants and plant-associated microbes. Consequently, they play a pivotal role in reshaping the microbiome. The biostimulant properties exhibited by these exudates position them as promising biological components for fostering cleaner and more sustainable agricultural systems.

Overexpression of chloroplastic Zea mays NADP-malic enzyme (ZmNADP-ME) confers tolerance to salt stress in Arabidopsis thaliana

The C4 plants photosynthesize better than C3 plants especially in arid environment. As an attempt to genetically convert C3 plant to C4, the cDNA of decarboxylating C4 type NADP-malic enzyme from Zea mays (ZmNADP-ME) that has lower Km for malate and NADP than its C3 isoforms, was overexpressed in Arabidopsis thaliana under the control of 35S promoter. Due to increased activity of NADP-ME in the transgenics the malate decarboxylation increased that resulted in loss of carbon skeletons needed for amino acid and protein synthesis. Consequently, amino acid and protein content of the transgenics declined. Therefore, the Chl content, photosynthetic efficiency (Fv/Fm), electron transport rate (ETR), the quantum yield of photosynthetic CO2 assimilation, rosette diameter, and biomass were lower in the transgenics. However, in salt stress (150 mM NaCl), the overexpressers had higher Chl, protein content, Fv/Fm, ETR, and biomass than the vector control. NADPH generated in the transgenics due to increased malate decarboxylation, contributed to augmented synthesis of proline, the osmoprotectant required to alleviate the reactive oxygen species-mediated membrane damage and oxidative stress. Consequently, the glutathione peroxidase activity increased and H2O2 content decreased in the salt-stressed transgenics. The reduced membrane lipid peroxidation and lower malondialdehyde production resulted in better preservation, of thylakoid integrity and membrane architecture in the transgenics under saline environment. Our results clearly demonstrate that overexpression of C4 chloroplastic ZmNADP-ME in the C3 Arabidopsis thaliana, although decrease their photosynthetic efficiency, protects the transgenics from salinity stress.

Proline, Cysteine and Branched-Chain Amino Acids in Abiotic Stress Response of Land Plants and Microalgae

Proteinogenic amino acids are the building blocks of protein, and plants synthesize all of them. In addition to their importance in plant growth and development, growing evidence underlines the central role played by amino acids and their derivatives in regulating several pathways involved in biotic and abiotic stress responses. In the present review, we illustrate (i) the role of amino acids as an energy source capable of replacing sugars as electron donors to the mitochondrial electron transport chain and (ii) the role of amino acids as precursors of osmolytes as well as (iii) precursors of secondary metabolites. Among the amino acids involved in drought stress response, proline and cysteine play a special role. Besides the large proline accumulation occurring in response to drought stress, proline can export reducing equivalents to sink tissues and organs, and the production of H2S deriving from the metabolism of cysteine can mediate post-translational modifications that target protein cysteines themselves. Although our general understanding of microalgae stress physiology is still fragmentary, a general overview of how unicellular photosynthetic organisms deal with salt stress is also provided because of the growing interest in microalgae in applied sciences.

Mathematical Estimation of Endogenous Proline as a Bioindicator to Regulate the Stress of Trivalent Chromium on Rice Plants Grown in Different Nitrogenous Conditions

The accumulation of proline impacts the defense mechanisms of plants against the harmful effects of adverse environmental conditions; however, its concentration in plants is associated with the metabolism of N. Therefore, the effects of exogenous organic [glutamate (Glu)/arginine (Arg)] and inorganic [nitrate (NO3-)/ammonium (NH4+)] N on the accumulation of proline (Pro) in rice plants under trivalent chromium [Cr(III)] stress were studied through using the mass balance matrix model (MBMM). Application of 'NH4+' showed the largest contribution to the Pro content in rice shoots under different concentrations of Cr(III), followed by 'NO3-', 'Arg', and 'Glu' applications. On the other hand, 'Arg' application displayed the largest contribution to the Pro content in roots under Cr(III) stress, followed by 'NH4+', 'Glu', and 'NO3-' applications. The combined application of 'NH4++Arg' showed the greatest contribution to the Pro content in both roots and shoots of Cr(III)-treated rice seedlings, while the application of 'NO3-+Glu' showed the least contribution to the Pro content in rice seedlings. The current study indicated that the endogenous level of Pro in rice seedlings is quite sensitive to Cr(III) stress under different N sources, and the mathematical modeling showed a reliable result while estimating the relationship between Pro content and N source application.

Mercury and amino acid content relations in northern pike (Esox lucius) in subarctic lakes along a climate-productivity gradient

Mercury is a highly toxic element for consumers, but its relation to amino acids and physiology of wild fish is not well known. The main aim of this study was to evaluate how total mercury content (THg) of northern pike (Esox lucius) is related to amino acids and potentially important environmental and biological factors along a climate-productivity gradient of ten subarctic lakes. Linear regression between THg and sixteen amino acids content [nmol mg-1 dry weight] from white dorsal muscle of pike from these lakes were tested. Lastly, a general linear model (GLM) for age-corrected THg was used to test which factors are significantly related to mercury content of pike. There was a positive relationship between THg and proline. Seven out of sixteen analysed amino acids (histidine, threonine, arginine, serine, glutamic acid, glycine, and aspartic acid) were significantly negatively related to warmer and more productive lakes, while THg showed a positive relationship. GLM model indicated higher THg was found in higher trophic level pike with lower cysteine content and inhabiting warmer and more productive lakes with larger catchment containing substantial proportion of peatland area. In general, THg was not only related to the biological and environmental variables but also to amino acid content.

Analysis of genetic diversity and genome-wide association study for drought tolerance related traits in Iranian bread wheat

BACKGROUND

Drought is most likely the most significant abiotic stress affecting wheat yield. The discovery of drought-tolerant genotypes is a promising strategy for dealing with the world's rapidly diminishing water resources and growing population. A genome-wide association study (GWAS) was conducted on 298 Iranian bread wheat landraces and cultivars to investigate the genetic basis of yield, yield components, and drought tolerance indices in two cropping seasons (2018-2019 and 2019-2020) under rainfed and well-watered environments.

RESULTS

A heatmap display of hierarchical clustering divided cultivars and landraces into four categories, with high-yielding and drought-tolerant genotypes clustering in the same group. The results of the principal component analysis (PCA) demonstrated that selecting genotypes based on the mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), and stress tolerance index (STI) can help achieve high-yield genotypes in the environment. Genome B had the highest number of significant marker pairs in linkage disequilibrium (LD) for both landraces (427,017) and cultivars (370,359). Similar to cultivars, marker pairs on chromosome 4A represented the strongest LD (r2 = 0.32). However, the genomes D, A, and B have the highest LD, respectively. The single-locus mixed linear model (MLM) and multi-locus random-SNP-effect mixed linear model (mrMLM) identified 1711 and 1254 significant marker-trait association (MTAs) (-log10 P > 3) for all traits, respectively. A total of 874 common quantitative trait nucleotides (QTNs) were simultaneously discovered by both MLM and mrMLM methods. Gene ontology revealed that 11, 18, 6, and 11 MTAs were found in protein-coding regions (PCRs) for spike weight (SW), thousand kernel weight (TKW), grain number per spike (GN), and grain yield (GY), respectively.

CONCLUSION

The results identified rich regions of quantitative trait loci (QTL) on Ch. 4A and 5A suggest that these chromosomes are important for drought tolerance and could be used in wheat breeding programs. Furthermore, the findings indicated that landraces studied in Iranian bread wheat germplasm possess valuable alleles, that are responsive to water-limited conditions. This GWAS experiment is one of the few types of research conducted on drought tolerance that can be exploited in the genome-mediated development of novel varieties of wheat.

Bridging the Gap: Combining Genomics and Transcriptomics Approaches to Understand Stylosanthes scabra, an Orphan Legume from the Brazilian Caatinga

Stylosanthes scabra is a scientifically orphaned legume found in the Brazilian Caatinga biome (a semi-arid environment). This work utilized omics approaches to investigate some ecophysiological aspects of stress tolerance/resistance in S. scabra, study its genomic landscape, and predict potential metabolic pathways. Considering its high-confidence conceptual proteome, 1694 (~2.6%) proteins were associated with resistance proteins, some of which were found in soybean QTL regions that confer resistance to Asian soybean rust. S. scabra was also found to be a potential source of terpenes, as biosynthetic gene clusters associated with terpene biosynthesis were identified in its genome. The analysis revealed that mobile elements comprised approximately 59% of the sequenced genome. In the remaining 41% of the sections, some of the 22,681 protein-coding gene families were categorized into two informational groups: those that were specific to S. scabra and those that expanded significantly compared to their immediate ancestor. Biological process enrichment analyses indicated that these gene families play fundamental roles in the adaptation of S. scabra to extreme environments. Additionally, phylogenomic analysis indicated a close evolutionary relationship between the genera Stylosanthes and Arachis. Finally, this study found a high number (57) of aquaporin-encoding loci in the S. scabra genome. RNA-Seq and qPCR data suggested that the PIP subfamily may play a key role in the species' adaptation to water deficit conditions. Overall, these results provide valuable insights into S. scabra biology and a wealth of gene/transcript information for future legume omics studies.

Transcriptomic and physiological approaches to decipher cold stress mitigation exerted by brown-seaweed extract application in tomato

Chilling temperatures represent a challenge for crop species originating from warm geographical areas. In this situation, biostimulants serve as an eco-friendly resource to mitigate cold stress in crops. Tomato (Solanum lycopersicum L.) is an economically important vegetable crop, but quite sensitive to cold stress, which it encounters in both open field and greenhouse settings. In this study, the biostimulant effect of a brown-seaweed extract (BSE) has been evaluated in tomato exposed to low temperature. To assess the product effects, physiological and molecular characterizations were conducted. Under cold stress conditions, stomatal conductance, net photosynthesis, and yield were significantly (p ≤ 0.05) higher in BSE-treated plants compared to the untreated ones. A global transcriptomic survey after BSE application revealed the impact of the BSE treatment on genes leading to key responses to cold stress. This was highlighted by the significantly enriched GO categories relative to proline (GO:0006560), flavonoids (GO:0009812, GO:0009813), and chlorophyll (GO:0015994). Molecular data were integrated by biochemical analysis showing that the BSE treatment causes greater proline, polyphenols, flavonoids, tannins, and carotenoids contents.The study highlighted the role of antioxidant molecules to enhance tomato tolerance to low temperature mediated by BSE-based biostimulant.

The Interplay of Physiological and Biochemical Response to Short-Term Drought Exposure in Garlic (Allium sativum L.)

The impacts of global climate change and a rapid increase in population have emerged as major concerns threatening global food security. Environmental abiotic stress, such as drought, severely impairs plants' morphology, physiology, growth, and yield more than many other environmental factors. Plants use a complex set of physiological, biochemical, and molecular mechanisms to combat the negative effects caused by drought-induced stress. The aim of this study was to investigate morphological, spectral, physiological, and biochemical changes occurring in 30 garlic accessions exposed to short-term drought stress in a greenhouse setting and to identify potential early drought-induced stress markers. The results showed that, on average, garlic plants exposed to drought conditions exhibited a decrease in assimilation, transpiration, and stomatal conductance of 39%, 52%, and 50%, respectively, and an average increase in dry matter and proline content of 10.13% and 14.29%, respectively. Nevertheless, a significant interaction between the treatment and accessions was observed in the investigated photosynthetic and biochemical parameters. The plants' early response to drought ranged from mild to strong depending on garlic accession. Multivariate analysis showed that accessions with a mild early drought response were characterized by higher values of assimilation, transpiration, and stomatal conductance compared to plants with moderate or strong early drought response. Additionally, accessions with strong early drought response were characterized by higher proline content, lipid peroxidation, and antioxidant capacity as measured by FRAP compared to accessions with mild-to-moderate early drought response.

Growth, Physiology and Nutritional Quality of C4 Halophyte Portulaca oleracea L. Grown Aeroponically in Different Percentages of Artificial Seawater under Different Light-Emitting Diode Spectral Qualities

Edible halophyte Portulaca oleracea L., known as purslane, was grown in two percentages of artificial seawater (ASW) under two combined red (R) and blue (B) LED spectra. High salinity (40% ASW) negatively affected shoot productivity and leaf growth of purslane compared to those grown in 10% ASW. Photosynthetic pigment and total reduced nitrogen concentrations were significantly higher in purslane grown in 10% ASW than in 40% ASW. However, LED spectral quality did not markedly influence these parameters. Grown in 10% ASW under R/B 2.2, purslane had the highest maximum nitrate reductase activity, while those in 40% ASW under R/B 2.2 had the highest activation state. Under both light qualities, purslane had a sevenfold increase in proline concentration in 40% ASW than in 10% ASW. Total phenolic compounds' concentration was the highest in 10% ASW under R/B 0.9, while there were no significant differences in the accumulation of total soluble sugars and ascorbic acids among all plants. Antioxidant enzymes activities were lower in 40% ASW under R/B 2.2 compared to the other conditions. In conclusion, salinity affected the yield, physiology and nutritional quality of purslane. The impacts of LED spectral quality on purslane were only reflected by certain physiological and nutritional parameters.

Geranium robertianum L. tolerates various soil types burdened with heavy metals

Many heavy metals (HMs) are essential micronutrients for the growth and development of plants. However, human activities such as mining, smelting, waste disposal, and industrial processes have led to toxic levels of HMs in soil. Fortunately, many plant species have developed incredible adaptive mechanisms to survive and thrive in such harsh environments. As a widespread and ruderal species, Geranium robertianum L. inhabits versatile soil types, both polluted and unpolluted. Considering the ubiquity of G. robertianum, the study aimed to determine whether geographically distant populations can tolerate HMs. We collected soil and plant samples from serpentine, an anthropogenic heavy metal contaminated, and a non-metalliferous site to study the physiological state of G. robertianum. HMs in soil and plants were determined using flame atomic absorption spectrometry. Spectrophotometric methods were used to measure the total content of chlorophylls a and b, total phenolics, phenolic acids, flavonoids, and proline. Principal component analysis (PCA) was used to investigate the potential correlation between HMs concentrations gathered from various soil types and plant samples and biochemical data acquired for plant material. A statistically significant difference was observed for all localities regarding secondary metabolite parameters. A positive correlation between Ni and Zn in soil and Ni and Zn in plant matter was observed (p<0.0005) indicating higher absorption. Regardless of high concentrations of heavy metals in investigated soils, G. robertianum displayed resilience and was capable of thriving. These results may be ascribed to several protective mechanisms that allow G. robertianum to express normal growth and development and act as a pioneer species.

From stressor to protector, UV-induced abiotic stress resistance

Plants are continuously exposed to combinations of abiotic and biotic stressors. While much is known about responses to individual stressors, understanding of plant responses to combinations of stressors is limited. The effects of combined exposure to drought and UV radiation are particularly relevant in the context of climate change. In this study it was explored whether UV-exposure can be used as a tool to prime stress-resistance in plants grown under highly protected culture conditions. It was hypothesised that priming mint plantlets (Mentha spicata L.) with a low-dose of UV irradiance can alleviate the drought effect caused by a change in humidity upon transplanting. Plants were grown for 30 days on agar in sealed tissue culture containers. During this period, plants were exposed to ~ 0.22 W m-2 UV-B for 8 days, using either UV-blocking or UV- transmitting filters. Plants were then transplanted to soil and monitored for a further 7 days. It was found that non-UV exposed mint plants developed necrotic spots on leaves, following transfer to soil, but this was not the case for plants primed with UV. Results showed that UV induced stress resistance is associated with an increase in antioxidant capacity, as well as a decrease in leaf area. UV-induced stress resistance can be beneficial in a horticultural setting, where priming plants with UV-B can be used as a tool in the production of commercial crops.

A general overview of the multifactorial adaptation to cold: biochemical mechanisms and strategies

Cold environments are more frequent than people think. They include deep oceans, cold lakes, snow, permafrost, sea ice, glaciers, cold soils, cold deserts, caves, areas at elevations greater than 3000 m, and also artificial refrigeration systems. These environments are inhabited by a diversity of eukaryotic and prokaryotic organisms that must adapt to the hard conditions imposed by cold. This adaptation is multifactorial and includes (i) sensing the cold, mainly through the modification of the liquid-crystalline membrane state, leading to the activation of a two-component system that transduce the signal; (ii) adapting the composition of membranes for proper functions mainly due to the production of double bonds in lipids, changes in hopanoid composition, and the inclusion of pigments; (iii) producing cold-adapted proteins, some of which show modifications in the composition of amino acids involved in stabilizing interactions and structural adaptations, e.g., enzymes with high catalytic efficiency; and (iv) producing ice-binding proteins and anti-freeze proteins, extracellular polysaccharides and compatible solutes that protect cells from intracellular and extracellular ice. However, organisms also respond by reprogramming their metabolism and specifically inducing cold-shock and cold-adaptation genes through strategies such as DNA supercoiling, distinctive signatures in promoter regions and/or the action of CSPs on mRNAs, among others. In this review, we describe the main findings about how organisms adapt to cold, with a focus in prokaryotes and linking the information with findings in eukaryotes.

Rhizobacteria-enhanced drought tolerance and post-drought recovery of creeping bentgrass involving differential modulation of leaf and root metabolism

Rhizobacteria that produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCd) that inhibits ethylene production may mitigate stress damages. The objectives of this study were to examine whether a novel strain of ACCd-producing bacteria, Paraburkholderia aspalathi "WSF23," promotes plant tolerance to drought stress and post-stress recovery and determine changes in metabolic profiles in leaves and roots associated with the positive ACCd-bacteria effects in cool-season perennial grass species. Creeping bentgrass (Agrostis Stolonifera L. cv. "Penncross") plants were inoculated with P. aspalathi "WSF23" and exposed to drought by withholding irrigation for 35 days, followed by re-watering for 15 days in growth chambers. Inoculated plants demonstrated increased turf quality, canopy density, and root growth during drought stress and more rapid re-growth upon re-watering. Metabolomic analysis demonstrated that inoculation with P. aspalathi "WSF 23" increased the content of metabolites in the metabolic pathways related to stress defense, including osmoregulation, cell wall stability, and antioxidant protection in both leaves and roots, as well as nitrogen metabolism in roots of creeping bentgrass exposed to drought stress. The promotion of post-stress recovery by P. aspalathi "WSF 23" was mainly associated with enhanced carbohydrate and pyrimidine metabolism and zeatin biosynthesis pathways in leaves and increased carbohydrates, biosynthesis of DNA and proteins, cellular metabolism, and TCA cycle activity in roots. These results provide insights into the metabolic pathways regulated by "WSF23," with the PGPR conferring improvements in drought stress tolerance and post-drought recovery in a perennial grass species.

Multifaceted Role of Nanomaterials in Modulating In Vitro Seed Germination, Plant Morphogenesis, Metabolism and Genetic Engineering

The agricultural practices of breeding, farm management and cultivation have improved production, to a great extent, in order to meet the food demands of a growing population. However, the newer challenges of climate change, global warming, and nutritional quality improvement will have to be addressed under a new scenario. Plant biotechnology has emerged as a reliable tool for enhancing crop yields by protecting plants against insect pests and metabolic engineering through the addition of new genes and, to some extent, nutritional quality improvement. Plant tissue culture techniques have provided ways for the accelerated clonal multiplication of selected varieties with the enhanced production of value-added plant products to increase modern agriculture. The in vitro propagation method has appeared as a pre-eminent approach for the escalated production of healthy plants in relatively shorter durations, also circumventing seasonal effects. However, there are various kinds of factors that directly or indirectly affect the efficiency of in vitro regeneration like the concentration and combination of growth regulators, variety/genotype of the mother plant, explant type, age of seedlings and other nutritional factors, and elicitors. Nanotechnology as one of the latest and most advanced approaches in the material sciences, and can be considered to be very promising for the improvement of crop production. Nanomaterials have various kinds of properties because of their small size, such as an enhanced contact surface area, increased reactivity, stability, chemical composition, etc., which can be employed in plant sciences to alter the potential and performance of plants to improve tissue culture practices. Implementing nanomaterials with in vitro production procedures has been demonstrated to increase the shoot multiplication potential, stress adaptation and yield of plant-based products. However, nanotoxicity and biosafety issues are limitations, but there is evidence that implies the promotion and further exploration of nanoparticles in agriculture production. The incorporation of properly designed nanoparticles with tissue culture programs in a controlled manner can be assumed as a new pathway for sustainable agriculture development. The present review enlists different studies in which treatment with various nanoparticles influenced the growth and biochemical responses of seed germination, as well as the in vitro morphogenesis of many crop species. In addition, many studies suggest that nanoparticles can be useful as elicitors for elevating levels of important secondary metabolites in in vitro cultures. Recent advancements in this field also depict the suitability of nanoparticles as a promising carrier for gene transfer, which show better efficiency than traditional Agrobacterium-mediated delivery. This review comprehensively highlights different in vitro studies that will aid in identifying research gaps and provide future directions for unexplored areas of research in important crop species.

Genetic architecture of tuber-bound free amino acids in potato and effect of growing environment on the amino acid content

Free amino acids in potato tubers contribute to their nutritional value and processing quality. Exploring the natural variation in their accumulation in tubers across diverse genetic backgrounds is critical to potato breeding programs aiming to enhance or partition their distribution effectively. This study assessed variation in the tuber-bound free amino acids in a diversity panel of tetraploid potato clones developed and maintained by the Texas A&M Potato Breeding Program to explore their genetic basis and to obtain genomic-estimated breeding values for applied breeding purposes. Free amino acids content was evaluated in tubers of 217 tetraploid potato clones collected from Dalhart, Texas in 2019 and 2020, and Springlake, Texas in 2020. Most tuber amino acids were not affected by growing location, except histidine and proline, which were significantly lower (- 59.0%) and higher (+ 129.0%), respectively, at Springlake, Texas (a location that regularly suffers from abiotic stresses, mainly high-temperature stress). Single nucleotide polymorphism markers were used for genome-wide association studies and genomic selection of clones based on amino acid content. Most amino acids showed significant variations among potato clones and moderate to high heritabilities. Principal component analysis separated fresh from processing potato market classes based on amino acids distribution patterns. Genome-wide association studies discovered 33 QTL associated with 13 free amino acids. Genomic-estimated breeding values were calculated and are recommended for practical potato breeding applications to select parents and advance clones with the desired free amino acid content.

Exogenous hydrogen sulfide improves salt stress tolerance of Reaumuria soongorica seedlings by regulating active oxygen metabolism

Hydrogen sulfide (H2S), as an endogenous gas signaling molecule, plays an important role in plant growth regulation and resistance to abiotic stress. This study aims to investigate the mechanism of exogenous H2S on the growth and development of Reaumuria soongorica seedlings under salt stress and to determine the optimal concentration for foliar application. To investigate the regulatory effects of exogenous H2S (donor sodium hydrosulfide, NaHS) at concentrations ranging from 0 to 1 mM on reactive oxygen species (ROS), antioxidant system, and osmoregulation in R. soongorica seedlings under 300 mM NaCl stress. The growth of R. soongorica seedlings was inhibited by salt stress, which resulted in a decrease in the leaf relative water content (LRWC), specific leaf area (SLA), and soluble sugar content in leaves, elevated activity levels of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT); and accumulated superoxide anion (O2-), proline, malondialdehyde (MDA), and soluble protein content in leaves; and increased L-cysteine desulfhydrase (LCD) activity and endogenous H2S content. This indicated that a high level of ROS was produced in the leaves of R. soongorica seedlings and seriously affected the growth and development of R. soongorica seedlings. The exogenous application of different concentrations of NaHS reduced the content of O 2-, proline and MDA, increased the activity of antioxidant enzymes and the content of osmoregulators (soluble sugars and soluble proteins), while the LCD enzyme activity and the content of endogenous H2S were further increased with the continuous application of exogenous H2S. The inhibitory effects of salt stress on the growth rate of plant height and ground diameter, the LRWC, biomass, and SLA were effectively alleviated. A comprehensive analysis showed that the LRWC, POD, and proline could be used as the main indicators to evaluate the alleviating effect of exogenous H2S on R. soongorica seedlings under salt stress. The optimal concentration of exogenous H2S for R. soongorica seedlings under salt stress was 0.025 mM. This study provides an important theoretical foundation for understanding the salt tolerance mechanism of R. soongorica and for cultivating high-quality germplasm resources.

A systematic analysis of the phloem protein 2 (PP2) proteins in Gossypium hirsutum reveals that GhPP2-33 regulates salt tolerance

BACKGROUND

Phloem protein 2 (PP2) proteins play a vital role in the Phloem-based defense (PBD) and participate in many abiotic and biotic stress. However, research on PP2 proteins in cotton is still lacking.

RESULTS

A total of 25, 23, 43, and 47 PP2 genes were comprehensively identified and characterized in G.arboretum, G.raimondii, G.barbadense, and G.hirsutum. The whole genome duplication (WGD) and allopolyploidization events play essential roles in the expansion of PP2 genes. The promoter regions of GhPP2 genes contain many cis-acting elements related to abiotic stress and the weighted gene co-expression network analysis (WGCNA) analysis displayed that GhPP2s could be related to salt stress. The qRT-PCR assays further confirmed that GhPP2-33 could be dramatically upregulated during the salt treatment. And the virus-induced gene silencing (VIGS) experiment proved that the silencing of GhPP2-33 could decrease salt tolerance.

CONCLUSIONS

The results in this study not only offer new perspectives for understanding the evolution of PP2 genes in cotton but also further explore their function under salt stress.

Population divergence in heat and drought responses of a coastal plant: from metabolic phenotypes to plant morphology and growth

Studying intraspecific variation in multistress responses is central for predicting and managing the population dynamics of wild plant species under rapid global change. Yet, it remains a challenging goal in this field to integrate knowledge on the complex biochemical underpinnings for the targeted 'non-model' species. Here, we studied divergence in combined drought and heat responses among Northern and Southern European populations of the dune plant Cakile maritima, by combining comprehensive plant phenotyping with metabolic profiling via FT-ICR-MS and UPLC-TQ-MS/MS. We observed pronounced constitutive divergence in growth phenology, leaf functional traits, and defence chemistry (glucosinolates and alkaloids) among population origins. Most importantly, the magnitude of growth reduction under drought was partly weaker in southern plants and associated with divergence in plastic growth responses (leaf abscission) and the modulation of primary and specialized metabolites with known central functions not only in plant abiotic but also in biotic stress responses. Our study indicates that divergent selection has shaped the constitutive and drought-/heat-induced expression of numerous morphological and biochemical functional traits to mediate higher abiotic stress resistance in southern Cakile populations, and highlights that metabolomics can be a powerful tool to explore the underlying mechanisms of local adaptation in 'non-model' species.

Heat shock protein TaHSP17.4, a TaHOP interactor in wheat, improves plant stress tolerance

Adaptation to drought and salt stresses is a fundamental part of plant cell physiology and is of great significance for crop production under environmental stress. Heat shock proteins (HSPs) are molecular chaperones that play a crucial role in folding, assembling, translocating, and degrading proteins. However, their underlying mechanisms and functions in stress tolerance remain elusive. Here, we identified the HSP TaHSP17.4 in wheat by analyzing the heat stress-induced transcriptome. Further analysis showed that TaHSP17.4 was significantly induced under drought, salt, and heat stress treatments. Intriguingly, yeast-two-hybrid analysis showed that TaHSP17.4 interacts with the HSP70/HSP90 organizing protein (HOP) TaHOP, which plays a significant role in linking HSP70 and HSP90. We found that TaHSP17.4- and TaHOP-overexpressing plants have a higher proline content and a lower malondialdehyde content than wild-type plants under stress conditions and display strong tolerance to drought, salt, and heat stress. Additionally, qRT-PCR analysis showed that stress-responsive genes relevant to reactive oxygen species scavenging and abscisic acid signaling pathways were significantly induced in TaHSP17.4- and TaHOP-overexpressing plants under stress conditions. Together, our findings provide insight into HSP functions in wheat and two novel candidate genes for improvement of wheat varieties.

A Novel Role of Medicago truncatula KNAT3/4/5-like Class 2 KNOX Transcription Factors in Drought Stress Tolerance

Class 2 KNOX homeobox transcription factors (KNOX2) play a role in promoting cell differentiation in several plant developmental processes. In Arabidopsis, they antagonize the meristematic KNOX1 function during leaf development through the modulation of phytohormones. In Medicago truncatula, three KNOX2 genes belonging to the KNAT3/4/5-like subclass (Mt KNAT3/4/5-like or MtKNOX3-like) redundantly works upstream of a cytokinin-signaling module to control the symbiotic root nodule formation. Their possible role in the response to abiotic stress is as-of-yet unknown. We produced transgenic M. truncatula lines, in which the expression of four MtKNOX3-like genes was knocked down by RNA interference. When tested for response to water withdrawal in the soil, RNAi lines displayed a lower tolerance to drought conditions compared to the control lines, measured as increased leaf water loss, accelerated leaf wilting time, and faster chlorophyll loss. Reanalysis of a transcriptomic M. truncatula drought stress experiment via cluster analysis and gene co-expression networks pointed to a possible role of MtKNOX3-like transcription factors in repressing a proline dehydrogenase gene (MtPDH), specifically at 4 days after water withdrawal. Proline measurement and gene expression analysis of transgenic RNAi plants compared to the controls confirmed the role of KNOX3-like genes in inhibiting proline degradation through the regulation of the MtPDH gene.

Comparative transcriptome profiling to unravel the key molecular signalling pathways and drought adaptive plasticity in shoot borne root system of sugarcane

Sugarcane root system comprises of superficial sett roots as well as deeply-penetrating shoot borne roots (SBR) with latter being the permanent root system. In sugarcane, the healthy SBR contributes to a better crop yield and it also helps to produce multiple ratoon crops after the harvest. There is a dearth of in-depth knowledge on SBR system architecture and its functional role in modern day commercial hybrids. A comprehensive phenotypic, anatomical and whole transcriptome profiling, conducted between the commercial sugarcane hybrids and a wild germplasm Erianthus, found a developmental delay in both initiation and establishment of the SBR in commercial hybrid compared to Erianthus. The SBR system in Erianthus proved to be an extensive drought-adaptive root system architecture that significantly contributes to drought tolerance. On the other hand, SBRs in the commercial hybrids showed an irreversible collapse and damage of the root cells under drought stress. The outcomes from the comparative analysis of the transcriptome data showed a significant upregulation of the genes that regulate important stress signalling pathways viz., sugar, calcium, hormone signalling and phenylpropanoid biosynthesis in the SBRs of Erianthus. It was found that through these key signalling pathways, Erianthus SBRs triggered the downstream signalling cascade to impart physiological responses like osmoprotection, modification of the cell walls, detoxification of reactive oxygen species, expression of drought responsive transcription factors, maintenance of cell stability and lateral root development. The current study forms a basis for further exploration of the Shoot Borne Root system as a valuable breeding target to develop drought tolerant sugarcane genotypes.

Primary Metabolite Screening Shows Significant Differences between Embryogenic and Non-Embryogenic Callus of Tamarillo (Solanum betaceum Cav.)

Tamarillo is a solanaceous tree that has been extensively studied in terms of in vitro clonal propagation, namely somatic embryogenesis. In this work, a protocol of indirect somatic embryogenesis was applied to obtain embryogenic and non-embryogenic callus from leaf segments. Nuclear magnetic resonance spectroscopy was used to analyze the primary metabolome of these distinct calli to elucidate possible differentiation mechanisms from the common genetic background callus. Standard multivariate analysis methods were then applied, and were complemented by univariate statistical methods to identify differentially expressed primary metabolites and related metabolic pathways. The results showed carbohydrate and lipid metabolism to be the most relevant in all the calli assayed, with most discriminant metabolites being fructose, glucose and to a lesser extent choline. The glycolytic rate was higher in embryogenic calli, which shows, overall, a higher rate of sugar catabolism and a different profile of phospholipids with a choline/ethanolamine analysis. In general, our results show that a distinct primary metabolome between embryogenic and non-embryogenic calli occurs and that intracellular levels of fructose and sucrose and the glucose to sucrose ratio seem to be good candidates as biochemical biomarkers of embryogenic competence.

Coal fly ash application as an eco-friendly approach for modulating the growth, yield, and biochemical constituents of Withania somnifera L. plants

The solid waste known as fly ash, which is produced when coal is burned in thermal power plants, is sustainably used in agriculture. It is an excellent soil supplement for plant growth and development since it contains some desired nutrients (macro and micro), as well as being porous. The present study was done to evaluate the effect of different fly ash levels on Withania somnifera. The present study aimed to assess the impact of various fly ash (FA) concentrations on growth, yield, photosynthetic pigments, biochemical parameters, and cell viability of W. somnifera. The results showed that FA enhanced physical and chemical properties of soil like pH, electric conductivity, porosity, water-holding capacity, and nutrients. The low doses of FA-amended soil (15%) significantly increased the shoot length (36%), root length (24.5%), fresh weight of shoots and roots (107.8 and 50.6%), dry weight of shoots and roots (61.9 and 47.1%), number of fruits (70.4%), carotenoid (43%), total chlorophyll (44.3%), relative water content (109.3%), protein content (20.4%), proline content (110.3%), total phenols (116.1%), nitrogen (20.3%), phosphorus (16.9%), and potassium (26.4%). On the other hand, the higher doses, i.e., 25% of fly ash showed a negative effect on all the above parameters and induced oxidative stress by increasing lipid peroxidation (33.1%) and hydrogen peroxide (102.0%) and improving the activities of antioxidant enzymes and osmolytes. Compared to the control plants, the plants growing in soil enriched with 15 and 25% fly ash had larger stomata pores when examined using a scanning electron microscope. In addition, according to a confocal microscopic analysis of the roots of W. somnifera, higher fly ash concentrations caused membrane damage, as evidenced by an increase in the number of stained nuclei. Moreover, several functional groups and peaks of the biomolecules represented in the control and 15% of fly ash were alcohols, phenols, allenes, ketenes, isocynates, and hydrocarbons. Gas chromatography-mass spectrometry analysis of the methanol extract of W. somnifera leaves cultivated in soil amended with 15% fly ash shows the presence of 47 bioactive compounds. The most abundant compounds in the methanol extract were cis-9-hexadecenal (22.33%), n-hexadecanoic acid (9.68%), cinnamic acid (6.37%), glycidyl oleate (3.88%), nonanoic acid (3.48%), and pyranone (3.57%). The lower concentrations of FA (15%) can be used to enhance plant growth and lower the accumulation of FA that results in environmental pollution.

Acinetobacter oleivorans IRS14 alleviates cold stress in wheat by regulating physiological and biochemical factors

AIMS

Climate change is responsible for extreme cold winters, causing a significant loss in crop yield and productivity due to chilling stress. This study aims to investigate the potential of psychrotrophic plant growth-promoting rhizobacteria (PGPR) strain to promote wheat growth under cold stress and explore the adaptive responses of wheat.

METHODS AND RESULTS

Wheat seeds and seedlings were inoculated with the psychrotrophic strain IRS14 and the plants were cultivated for five weeks at 6°C ± 2°C. The genetic, biochemical, physiological, and molecular analysis of the bacterium and plant was done to evaluate the effect of the PGPR strain in alleviating chilling stress. IRS14 possesses antioxidant activity and produced multiple phytohormones, which enhanced seed germination (∼50%) and plant growth (∼50%) during chilling stress.

CONCLUSIONS

Here, we reported that the application of IRS14 helps to regulate the biochemical and metabolic pathways in wheat plants. It alleviates chilling stress and increases plant growth rate and biomass. Strain IRS14 in wheat effectively increased chlorophyll content, antioxidants, carotenoid, proline, and endogenous phytohormones compared with untreated wheat.

Application of green synthesized bimetallic nZVI-Cu nanoparticle as a sustainable alternative to chemical fertilizers to enhance growth and photosynthetic efficiency of rice seedlings

Application of nanomaterials in agriculture has been extensively explored over the past decade leading to a wide ambit of nanoparticle-based agrochemicals. Metallic nanoparticles consisting of plant macro- and micro-nutrients have been used as nutritional supplements for plants through soil amendments, foliar sprays, or seed treatment. However, most of these studies emphasize monometallic nanoparticles which limit the range of usage and effectivity of such nanoparticles (NPs). Hence, we have employed a bimetallic nanoparticle (BNP) consisting of two different micro-nutrients (Cu & Fe) in rice plants to test its efficacy in terms of growth and photosynthesis. Several experiments were designed to assess growth (root-shoot length, relative water content) and photosynthetic parameters (pigment content, relative expression of rbcS, rbcL & ChlGetc.). To determine whether the treatment induced any oxidative stress or structural anomalies within the plant cells, histochemical staining, anti-oxidant enzyme activities, FTIR, and SEM micrographs were undertaken. Results indicated that foliar application of 5 mg L-1 BNP increased vigor and photosynthetic efficiency whereas 10 mg L-1 concentration induced oxidative stress to some extent. Furthermore, the BNP treatment did not perturb the structural integrity of the exposed plant parts and also did not induce any cytotoxicity. Application of BNPs in agriculture has not been explored extensively to date and this study is one of the first reports that not only documents the effectivity of Cu-Fe BNP but also critically explores the safety of its usage on rice plants making it a useful lead to design new BNPs and explore their efficacy.

Proline Enhances Resistance and Recovery of Oilseed Rape after a Simulated Prolonged Drought

This study was carried out to evaluate the effect of exogenous proline on the growth, biochemical responses, and plant recovery of drought-stressed oilseed rape plants after renewed irrigation. The experiment was conducted under controlled laboratory conditions. After 21 days of cultivation, 3-4 leaf stage seedlings were sprayed with proline (1 mM), then subjected to prolonged drought stress for 8 days to achieve a severe water deficit, next, irrigation was resumed and recovery was assessed after 4 days. The results show that exogenous application of proline reduced the drought-induced growth inhibition of seedlings while maintaining relative water content (RWC) and growth parameters closer to those of irrigated plants. Proline had a positive effect on chlorophyll accumulation and membrane permeability while decreasing ethylene, H₂O₂, and MDA levels. Moreover, after 4 days of recovery, the H₂O₂ content of the proline-treated plants was significantly lower (2-fold) and the MDA content was close to that of continuously irrigated plants. Thus, all these biochemical reactions influenced plant survival: after drought + proline treatment, the number of surviving plants was two times higher than that of drought-treated plants. The findings show that exogenous proline has antioxidant, osmotic, and growth-promoting properties that improve the drought tolerance of winter oilseed rape plants and is, therefore, beneficial for drought adaptation in oilseed rape.

The Effects of Seed Pretreatment with Endophytic Bacteria Bacillus subtilis on the Water Balance of Spring and Winter Wheat Seedlings under Short-Time Water Deficit

We investigated the effect of pre-sowing seed treatment with endophytic Bacillus subtilis 10-4 (B. subtilis) on spring and winter wheat (Triticum aestivum L.; cultivars Ekada-70 (Ek) and Scepter (Sc), respectively) growth and tolerance under 1-24 h of drought stress, modulated by 12% polyethylene glycol 6000 (PEG). The results showed that drought decreased transpiration intensity (TI), root relative water content (RWC), osmotic potential (Ψ_π) of cell sap, and induced proline accumulation and electrolyte leakage (EL) in both wheat cultivars. It was revealed that Sc was more responsive to PEG and B. subtilis treatments than Ek. Under drought, Ek did not significantly change root length, shoot height, or dry biomass. The pretreatment of wheat plants with B. subtilis performed significantly better under drought conditions through the enhanced TI, RWC, and Ψ_π of the cell sap in comparison with the plants treated with 12% PEG alone. B. subtilis also reduced stress-caused EL, especially in the Sc cultivar. Under water deficit wheat seedlings, pretreated with B. subtilis, have a higher proline accumulation in comparison to untreated stressed plants. Taken together, our results demonstrate the crucial role of endophytic B. subtilis in ameliorating the adverse effects of water stress on the water balance of both winter and spring wheat cultivars.

Combined Effect of Salicylic Acid and Proline Mitigates Drought Stress in Rice (Oryza sativa L.) through the Modulation of Physiological Attributes and Antioxidant Enzymes

Salicylic acid (SA) and proline exhibit protective effects against a wide range of stresses. However, the combined impact of SA and proline on rice under drought stress is still unknown. Therefore, we investigated the protective roles of SA and/or proline in conferring drought tolerance in rice. There were eight treatments comprising the control (T1; 95-100% FC), 1.5 mM SA (T2), 2 mM proline (T3), 0.75 mM SA + 1 mM proline (T4), 45-50% FC (T5, drought stress), T5 + 1.5 mM SA (T6), T5 + 2 mM proline (T7), and T5 + 0.75 mM SA + 1 mM proline (T8), and two rice varieties: BRRI dhan66 and BRRI dhan75. Drought stress significantly decreased the plant growth, biomass, yield attributes, photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), photosynthetic pigments (chlorophyll and carotenoids content), relative water content (RWC), membrane stability index (MSI), soluble sugar and starch content, and uptake of N, P and K⁺ in roots and shoots. Drought-induced oxidative stress in the form of increased hydrogen peroxide (H₂O₂) production and lipid peroxidation (MDA) was observed. The combined application of SA (0.75 mM) + proline (1 mM) was found to be more effective than the single application of either for drought stress mitigation in rice. A combined dose of SA + proline alleviated oxidative stress through boosting antioxidant enzymatic activity in contrast to their separate application. The application of SA + proline also enhanced proline, soluble sugar and starch content, which resulted in the amelioration of osmotic stress. Consequently, the combined application of SA and proline significantly increased the gas exchange characteristics, photosynthetic pigments, RWC, MSI, nutrient uptake, plant growth, biomass and yield of rice. Therefore, the combined application of SA and proline alleviated the detrimental impacts of drought stress more pronouncedly than their separate application did by increasing osmoprotectants, improving nutrient transport, up-regulating antioxidant enzyme activity and inhibiting oxidative stress.

Sunflower Hybrids and Inbred Lines Adopt Different Physiological Strategies and Proteome Responses to Cope with Water Deficit

Sunflower is a hybrid crop that is considered moderately drought-tolerant and adapted to new cropping systems required for the agro-ecological transition. Here, we studied the impact of hybridity status (hybrids vs. inbred lines) on the responses to drought at the molecular and eco-physiological level exploiting publicly available datasets. Eco-physiological traits and leaf proteomes were measured in eight inbred lines and their sixteen hybrids grown in the high-throughput phenotyping platform Phenotoul-Heliaphen. Hybrids and parental lines showed different growth strategies: hybrids grew faster in the absence of water constraint and arrested their growth more abruptly than inbred lines when subjected to water deficit. We identified 471 differentially accumulated proteins, of which 256 were regulated by drought. The amplitude of up- and downregulations was greater in hybrids than in inbred lines. Our results show that hybrids respond more strongly to water deficit at the molecular and eco-physiological levels. Because of presence/absence polymorphism, hybrids potentially contain more genes than their parental inbred lines. We propose that detrimental homozygous mutations and the lower number of genes in inbred lines lead to a constitutive defense mechanism that may explain the lower growth of inbred lines under well-watered conditions and their lower reactivity to water deficit.

A novel study for producing complexed and encapsulated nutrients at nanometric scale to enhance plant growth

Complexation of micronutrients with complexing agents reduce undesirable reactions of fertilizers in soil water system. In the form of complex structure nutrients remain available to plants in the useable form. Nanoform fertilizer enhances the surface area of particles and less amount of fertilizer contact with large area of plant roots which reduce fertilizer cost. Controlling release of fertilizer using polymeric material like sodium alginate makes agriculture practices more efficient and cost effective. Several fertilizers and nutrients are used at a large scale to improve crop yields globally and almost more than half goes to waste. Therefore, there is a dire need to improve plant-available nutrients in soil, using feasible, environmentally friendly technologies. In the present research, complexed micronutrients were successfully encapsulated using a novel technique at nanometric scale. The nutrients were complexed with proline and encapsulated using sodium alginate (polymer). Sweet basil was subjected to seven treatments over three months in a moderately controlled environment (25 °C of temperature and 57% of humidity) to study the effects of synthesized complexed micronutrient nano fertilizers. The structural modifications of the complexed micronutrient nanoforms of fertilizers were examined, through X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The size of manufactured fertilizers was between 1 and 200 nm. Fourier transform infrared (FTIR) spectroscopy stretching vibration peaks at 1600.9 cm^-1 (C=O), 3336 cm^-1 (N-H) and at 1090.2 cm^-1 (N-H in a twisting and rocking) corresponds to the pyrrolidine ring. Gas chromatography-mass spectrometry was used to analyze the chemical makeup of the essential oil of the basil plants. Essential oil yield of basil plants increased from 0.0035 to 0.1226% after treatments. The findings of the present research show that complexation and encapsulation improve crop quality, essential oil yield, and antioxidant potential of basil.

Eukaryotic Translation Elongation Factor OsEF1A Positively Regulates Drought Tolerance and Yield in Rice

Drought is one of the most serious stresses affecting rice growth. Drought stress causes accelerated senescence, reduced fertility, and subsequent reductions in crop yield. Eukaryotic translation elongation factor EF1A is an important multifunctional protein that plays an essential role in the translation of eukaryotic proteins. In this study, we localized and cloned the OsEF1A gene in rice (Oryza sativa) in order to clarify its role in drought tolerance and yield. Subcellular localization revealed that it was mainly localized to the cell membrane, cytoskeleton and nucleus. Compared with the wild-type, OsEF1A overexpressing transgenic plants had significantly more tillers and grains per plant, resulting in a significantly higher yield. Increases in the relative water content and proline content were also observed in the transgenic seedlings under drought stress, with a decrease in the malondialdehyde content, all of which are representative of drought tolerance. Taken together, these findings suggest that OsEF1A plays a positive regulatory role in rice nutritional development under drought stress. These findings will help support future studies aimed at improving yield and stress tolerance in rice at the molecular level, paving the way for a new green revolution.

Development of light-emitting Episcia lilacina leaf by applying Vibrio campbellii RMT1 and extending the glowing by CaCl2 and yeast extract

Glowing Episcia lilacina was generated through foliar application of the bioluminescent bacterium Vibrio campbellii RMT1. Firstly, different nutrient formulas were tested, incorporating yeast extract and various inorganic salts, such as CaCl₂, MgCl₂, MgSO₄, KH₂PO₄, K₂HPO₄, and NaCl, in order to enhance bacterial growth and light emission. The combination of 0.15% of yeast extract and 0.3% of CaCl₂ in a nutrient broth (NB) + 1% NaCl medium extended light emission to 24 h and resulted in higher light intensity compared to other combinations of yeast extract and inorganic salts. The peak intensity reached approximately 1.26 × 10⁸ relative light units (RLU) at 7 h. The optimal presence of inorganic salt ions likely contributed to enhanced light emission, while the yeast extract acted as a nutrient source. Secondly, the effect of proline on salt-induced stress symptoms was investigated by applying 20 mM proline to the glowing plant. Additionally, a 0.5% agar nutrient was spread on the leaves prior to bacteria application to support bacterial growth and penetration. Exogenous proline application led to a significant accumulation of proline in plant cells, resulting in decreased malondialdehyde (MDA) levels. However, the proline accumulation also reduced the light intensity of the bioluminescent bacteria. This study demonstrates the potential for generating light on a living plant using bioluminescent bacteria. Further understanding of the interaction between plants and light-emitting bacteria could contribute to the development of sustainably light-emitting plants.

Management of Antracnosis with Electrochemically Activated Salt Solutions (EASSs) on Bean Culture

Common bean (Phaseolus vulgaris L.) is an important crop for food security and for national economics for several countries worldwide. One of the most important factors of risk in common bean production is the fungal disease anthracnose caused by Colletotrichum lindemuthianum, which, in some cases, causes complete yield losses; this kind of plant disease is usually managed through the application of chemical products such as fungicides that are commonly not accepted by society. This rejection is based on the relationship of pesticides with health damage and environmental contamination. In order to help in solving these drawbacks, the present work proposes the use of electrochemically activated salt solutions (EASSs) as a safer pathogen control agent in crops, due to it having shown an elicitor and biostimulant effect on plants. With this background, this manuscript presents in vitro results of the evaluation of the inhibitory effect for multiple bean pathogens and in vivo results of EASS in the common bean-Colletotrichum pathosystem by evaluation of the infection severity and defense activation, such as secondary metabolite production and antioxidant activity. EASS presence in growth media had a strong inhibitory effect at the beginning of experiments for some of the evaluated fungi. EASSs showed an effect against the development of the disease when applied in specific doses to prevent distress in plants.

Comparative Evaluation of Antioxidant Status and Mineral Composition of Diploschistes ocellatus, Calvatia candida (rostk.) Hollós, Battarrea phalloides and Artemisia lerchiana in Conditions of High Soil Salinity

Natural reserves play a fundamental role in maintaining flora and fauna biodiversity, but the biochemical characteristics of such ecosystems have been studied in an extremely fragmentary way. For the first time, mineral composition and antioxidant status of three systematic groups of organisms, lichens (Diplischistes ocellatus), mushrooms (Calvatia candida and Battarrea phalloides) and wormwood (Artemisia lerchiana) have been described at the territory of Bogdinsko-Baskunchak Nature Reserve (Astrakhan region, Russia), characterized by high salinity and solar radiation, and water deficiency. Through ICP-MS, it was determined that scale lichen D. ocellatus accumulated up to 10-15% Ca, 0.5% Fe, 15 mg kg^-1 d.w. iodine (I), 54.5 mg kg^-1 Cr. Battarrea phalloides demonstrated anomalously high concentrations of B, Cu, Fe, Mn Se, Zn, Sr and low Na levels, contrary to Calvatia candida mushrooms accumulating up to 10,850 mg kg^-1 Na and only 3 mg kg^-1 Sr. The peculiarity of A. lerchiana plants was the high accumulation of B (22.23 mg kg^-1 d.w.), Mn (57.48 mg kg^-1 d.w.), and antioxidants (total antioxidant activity: 68.6 mg GAE g^-1 d.w.; polyphenols: 21.0 mg GAE g^-1 d.w.; and proline: 5.45 mg g^-1 d.w.). Diploschistes ocellatus and Calvatia candida demonstrated the lowest antioxidant status: 3.6-3.8 mg GAE g^-1 d.w. total antioxidant activity, 1.73-2.10 mg GAE g^-1 d.w. polyphenols and 2.0-5.3 mg g^-1 d.w. proline. Overall, according to the elemental analysis of lichen from Baskunchak Nature Reserve compared to the Southern Crimean seashore, the vicinity of Baskunchak Salty Lake elicited increased environmental levels of Cr, Si, Li, Fe, Co, Ni and Ca.

Glutathione to ameliorate growth criterions and chemical constituents of geranium irrigated with salt water

Essential oil of geranium (Pelargonium graveolensL) has biological activities that make it used in food and pharmaceutical manufactures. High salinity is one of the factors that lead to lack of expansion in the production of medicinal and aromatic plants, especially in the new reclaimed soil located at arid and semi arid regions. Glutathione is a natural antioxidant that can help plants to withstand unfavorable environmental conditions such as the salinity of irrigation water. This trial aimed to diminish the undesirable effect of exposure to irrigation with salt water on geranium herbs through subjected them to exogenous application of glutathione. Geranium plants were irrigated with various concentrations of salt water with sodium chloride (0.0, 34.2, 51.3, and 68.4 mM) without (0 mg/L) or with glutathione (375 mg/L). Plants exposed to various rates of saline irrigation water with glutathione resulted in higher values of growth criterions (fresh and dry aerial parts), photosynthetic pigments, carbohydrates, protein, proline, essential oil (% or yield), antioxidant enzymes (peroxidase and superoxide dismutase), nitrogen, phosphorous, potassium, calcium, iron, zinc, manganese and copper than those subjected to saline irrigation water without glutathione. Higher amounts were found in sodium and chloride of plant treated with saline irrigation water than those treated saline irrigation water with glutathione. It may be summarized that productivity of geranium plants can be improved with adapting them under saline irrigation conditions by adding glutathione. This trial benefits the producers of geranium to alleviate the hurtful effects of salinity in reclaimed regions with adding glutathione.

Spirulina platensis extract improves the production and defenses of the common bean grown in a heavy metals-contaminated saline soil

Plants have to cope with several abiotic stresses, including salinity and heavy metals (HMs). Under these stresses, several extracts have been used as effective natural biostimulants, however, the use of Spirulina platensis (SP) extract (SPE) remains elusive. The effects of SPE were evaluated as soil addition (SA) and/or foliar spraying (FS) on antioxidant defenses and HMs content of common bean grown in saline soil contaminated with HMs. Individual (40 or 80 mg SPE/hill added as SA or 20 or 40 mg SPE/plant added as FS) or integrative (SA+FS) applications of SPE showed significant improvements in the following order: SA-80+FS-40 > SA-80+FS-20 > SA-40+FS-40 > SA-40+FS-20 > SA-80 > SA-40 > FS-40 > FS-20 > control. Therefore, the integrative SA+FS with 40 mg SP/plant was the most effective treatment in increasing plant growth and production, overcoming stress effects and minimizing contamination of the edible part. It significantly increased plant growth (74%-185%) and yield (107%-227%) by enhancing net photosynthetic rate (78.5%), stomatal conductance (104%), transpiration rate (124%), and contents of carotenoids (60.0%), chlorophylls (49%-51%), and NPK (271%-366%). These results were concurrent with the marked reductions in malondialdehyde (61.6%), hydrogen peroxide (42.2%), nickel (91%-94%), lead (80%-9%), and cadmium (74%-91%) contents due to the improved contents of glutathione (87.1%), ascorbate (37.0%), and α-tocopherol (77.2%), and the activities of catalase (18.1%), ascorbate peroxidase (18.3%), superoxide dismutase (192%), and glutathione reductase (52.2%) as reinforcing mechanisms. Therefore, this most effective treatment is recommended to mitigate the stress effects of salinity and HMs on common bean production while minimizing HMs in the edible part.

Expression of TaNCL2-A ameliorates cadmium toxicity by increasing calcium and enzymatic antioxidants activities in arabidopsis

Cadmium (Cd) is a heavy metal that occurs naturally in the environment and is toxic to both animals and plants. The impact of Cd toxicity is shown to be reduced by the exogenous application of calcium (Ca) in crop plants. The sodium/calcium exchanger-like (NCL) protein is involved in Ca enrichment in the cytoplasm by transporting it from the vacuole in the exchange of cytosolic sodium (Na). However, it has not been utilized to ameliorate the Cd toxicity, to date. An elevated expression of TaNCL2-A gene in the root and shoot tissues of bread wheat seedlings, and a higher growth rate of recombinant yeast cells, suggested its role in Cd stress response. The TaNCL2-A expressing transgenic Arabidopsis lines exhibited significant Cd tolerance with increased Ca (∼10-fold) accumulation. The proline content and antioxidant enzymes activities were increased while oxidative stress-related molecules such as H₂O₂ and MDA were reduced in the transgenic lines. In addition, the growth and yield parameters of transgenic lines such as seed germination rate, root length, leaf biomass, leaf area index, rosette diameter, leaf length and width, and silique count, along with various physiological indicators like chlorophyll, carotenoid, and relative water contents were also improved in comparison to the control plants. Further, the transgenic lines exhibited significant salinity and osmotic stress tolerance, as well. Taken together, these results suggested that the TaNCL2-A could mitigate Cd toxicity along with salinity and osmotic stress. This gene may also be utilized for phytoremediation and Cd sequestration in future studies.

Sweet Potato as a Key Crop for Food Security under the Conditions of Global Climate Change: A Review

Sweet potato is one of the most economically important crops for addressing global food security and climate change issues, especially under conditions of extensive agriculture, such as those found in developing countries. However, osmotic stress negatively impacts the agronomic and economic productivity of sweet potato cultivation by inducing several morphological, physiological, and biochemical changes. Plants employ many signaling pathways to respond to water stress by modifying their growth patterns, activating antioxidants, accumulating suitable solutes and chaperones, and making stress proteins. These physiological, metabolic, and genetic modifications can be employed as the best indicators for choosing drought-tolerant genotypes. The main objective of sweet potato breeding in many regions of the world, especially those affected by drought, is to obtain varieties that combine drought tolerance with high yields. In this regard, the study of the physiological and biochemical features of certain varieties is important for the implementation of drought resistance measures. Adapted genotypes can be selected and improved for particular growing conditions by using suitable tools and drought tolerance-related selection criteria. By regulating genetics in this way, the creation of drought-resistant varieties may become cost-effective for smallholder farmers. This review focuses on the drought tolerance mechanisms of sweet potato, the effects of drought stress on its productivity, its crop management strategies for drought mitigation, traditional and molecular sweet potato breeding methods for drought tolerance, and the use of biotechnological methods to increase the tolerance of sweet potato to drought.

Salt and drought stress-mitigating approaches in sugar beet (Beta vulgaris L.) to improve its performance and yield

MAIN CONCLUSION

Although sugar beet is a salt- and drought-tolerant crop, high salinity, and water deprivation significantly reduce its yield and growth. Several reports have demonstrated stress tolerance enhancement through stress-mitigating strategies including the exogenous application of osmolytes or metabolites, nanoparticles, seed treatments, breeding salt/drought-tolerant varieties. These approaches would assist in achieving sustainable yields despite global climatic changes. Sugar beet (Beta vulgaris L.) is an economically vital crop for ~ 30% of world sugar production. They also provide essential raw materials for bioethanol, animal fodder, pulp, pectin, and functional food-related industries. Due to fewer irrigation water requirements and shorter regeneration time than sugarcane, beet cultivation is spreading to subtropical climates from temperate climates. However, beet varieties from different geographical locations display different stress tolerance levels. Although sugar beet can endure moderate exposure to various abiotic stresses, including high salinity and drought, prolonged exposure to salt and drought stress causes a significant decrease in crop yield and production. Hence, plant biologists and agronomists have devised several strategies to mitigate the stress-induced damage to sugar beet cultivation. Recently, several studies substantiated that the exogenous application of osmolytes or metabolite substances can help plants overcome injuries induced by salt or drought stress. Furthermore, these compounds likely elicit different physio-biochemical impacts, including improving nutrient/ionic homeostasis, photosynthetic efficiency, strengthening defense response, and water status improvement under various abiotic stress conditions. In the current review, we compiled different stress-mitigating agricultural strategies, prospects, and future experiments that can secure sustainable yields for sugar beets despite high saline or drought conditions.

Allantoin alleviates chromium phytotoxic effects on wheat by regulating osmolyte accumulation, secondary metabolism, ROS homeostasis and nutrient acquisition

Allantoin is a nitrogen metabolite with significant potential to mediate plant defense responses under salinity. However, the impact of allantoin on ions homeostasis and ROS metabolism has yet to be established in plants under Cr toxicity. In the current study, chromium (Cr) notably diminished growth, photosynthetic pigments, and nutrient acquisition in two wheat cultivars (Galaxy-2013 and Anaj-2017). Plants subjected to Cr toxicity displayed excessive Cr accumulation. Chromium produced substantial oxidative stress reflected as higher levels of O₂^•, H₂O₂, MDA, methylglyoxal (MG) and lipoxygenase activity. Plants manifested marginally raised antioxidant enzyme activities due to Cr stress. Further, reduced glutathione (GSH) levels diminished with a concurrent rise in oxidized glutathione levels (GSSG). Plants exhibited a considerable abridge in GSH:GSSG due to Cr toxicity. Allantoin (200 and 300 mg L¹) subsided metal phytotoxic effects by strengthening the activities of antioxidant enzymes and levels of antioxidant compounds. Plants administered allantoin displayed a considerable rise in endogenous H₂S and nitric oxide (NO) levels that, in turn, lessened oxidative injury in Cr-stressed plants. Allantoin diminished membrane damage and improved nutrient acquisition under Cr stress. Allantoin markedly regulated the uptake and distribution of Cr in wheat plants, abridging the degree of metal phytotoxic effect.

PeMPK17 interacts with PeMKK7 and participates in para-hydroxybenzoic acid stress resistance by removing reactive oxygen species

Mitogen-activated protein kinase (MAPK) plays a crucial role in plant stress response. Poplar is one of the most important afforestation and timber species and inevitably encounters allelopathy effects during continuous cropping. para-hydroxybenzoic acid (pHBA) is a primary soil allelochemical, which can restrict the growth and biomass of poplar. However, the involvement of MAPKs in the underlying physiological and molecular regulatory mechanisms in response to pHBA stress remains unclear. In this study, PeMPK17, a gene encoding a group D MAPK, was cloned from Populus × euramericana. PeMPK17 protein was localized in both nucleus and plasma membrane. Quantitative real-time polymerase chain reaction analysis demonstrated that PeMPK17 expression in poplar increased when treated with pHBA, PEG, and H₂O₂. Exogenous pHBA and H₂O₂ induced PeMPK17 expression mediated by reactive oxygen species (ROS). The transgenic poplar plants overexpressing PeMPK17 demonstrated attenuated phenotypic injury, higher relative water content in leaves, and lower ion leakage under pHBA stress. In transgenic poplar, the activity and expression of antioxidant enzymes including superoxide dismutase, peroxidase, and catalase increased, while the content of H₂O₂, O₂·^-, and malondialdehyde decreased. These results suggested that PeMPK17 protects cell membranes from oxidative damage by removing excess ROS. In addition, overexpression of PeMPK17 promoted osmoprotectant accumulation including soluble sugar and free proline, which may aid in the regulation of ROS balance under pHBA treatment. Furthermore, the interaction between PeMPK17 and PeMKK7 was confirmed. Collectively, these data identify the molecular mechanisms and signal pathways associated with PeMPK17 that regulate pHBA response in poplar.

Aluminum-Immobilizing Rhizobacteria Modulate Root Exudation and Nutrient Uptake and Increase Aluminum Tolerance of Pea Mutant E107 (brz)

It is well known that plant-growth-promoting rhizobacteria (PGPRs) increase the tolerance of plants to abiotic stresses; however, the counteraction of Al toxicity has received little attention. The effects of specially selected Al-tolerant and Al-immobilizing microorganisms were investigated using pea cultivar Sparkle and its Al-sensitive mutant E107 (brz). The strain Cupriavidus sp. D39 was the most-efficient in the growth promotion of hydroponically grown peas treated with 80 µM AlCl₃, increasing the plant biomass of Sparkle by 20% and of E107 (brz) by two-times. This strain immobilized Al in the nutrient solution and decreased its concentration in E107 (brz) roots. The mutant showed upregulated exudation of organic acids, amino acids, and sugars in the absence or presence of Al as compared with Sparkle, and in most cases, the Al treatment stimulated exudation. Bacteria utilized root exudates and more actively colonized the root surface of E107 (brz). The exudation of tryptophan and the production of IAA by Cupriavidus sp. D39 in the root zone of the Al-treated mutant were observed. Aluminum disturbed the concentrations of nutrients in plants, but inoculation with Cupriavidus sp. D39 partially restored such negative effects. Thus, the E107 (brz) mutant is a useful tool for studying the mechanisms of plant-microbe interactions, and PGPR plays an important role in protecting plants against Al toxicity.

Oxidative stress indices induced by industrial and urban PM2.5-bound metals in A549 cells

The detrimental effects of atmospheric fine particulate matter (PM_2.5) on human health are of major global concern. PM_2.5-bound metals are toxic compounds that contribute to cellular damage. To investigate the toxic effects of water-soluble metals on human lung epithelial cells and their bioaccessibility to lung fluid, PM_2.5 samples were collected from both urban and industrial areas in the metropolitan city of Tabriz, Iran. Oxidative stress indices, including proline content, total antioxidant capacity (TAC), cytotoxicity, and DNA damage levels of water-soluble components of PM_2.5, were evaluated. Furthermore, an in vitro test was conducted to assess the bioaccessibility of various PM_2.5-bound metals to the respiratory system using simulated lung fluid. PM_2.5 average concentrations in urban and industrial areas were 83.11 and 97.71 μg/m³, respectively. The cytotoxicity effects of PM_2.5 water-soluble constituents from urban areas were significantly higher than in industrial areas and the IC₅₀ was found to be 96.76 ± 3.34 and 201.31 ± 5.96 μg/mL for urban and industrial PM_2.5 samples, respectively. In addition, higher PM_2.5 concentrations increased the proline content in a concentration-dependent manner in A549 cells, which plays a protective role against oxidative stress and prevents PM_2.5-induced DNA damage. Also, the partial least squares regression revealed that Be, Cd, Co, Ni, and Cr, were significantly correlated with DNA damage and proline accumulation, which caused cell damage through oxidative stress. The results of this study showed that PM_2.5-bound metals in highly polluted metropolitan city caused substantial changes in the cellular proline content, DNA damage levels and cytotoxicity in human lung A549 cells.

Autophagy and multivesicular body pathways cooperate to protect sulfur assimilation and chloroplast functions

Autophagy and multivesicular bodies (MVBs) represent 2 closely related lysosomal/vacuolar degradation pathways. In Arabidopsis (Arabidopsis thaliana), autophagy is stress-induced, with deficiency in autophagy causing strong defects in stress responses but limited effects on growth. LYST-INTERACTING PROTEIN 5 (LIP5) is a key regulator of stress-induced MVB biogenesis, and mutation of LIP5 also strongly compromises stress responses with little effect on growth in Arabidopsis. To determine the functional interactions of these 2 pathways in Arabidopsis, we generated mutations in both the LIP5 and AUTOPHAGY-RELATED PROTEIN (ATG) genes. atg5/lip5 and atg7/lip5 double mutants displayed strong synergistic phenotypes in fitness characterized by stunted growth, early senescence, reduced survival, and greatly diminished seed production under normal growth conditions. Transcriptome and metabolite analysis revealed that chloroplast sulfate assimilation was specifically downregulated at early seedling stages in the atg7/lip5 double mutant prior to the onset of visible phenotypes. Overexpression of adenosine 5'-phosphosulfate reductase 1, a key enzyme in sulfate assimilation, substantially improved the growth and fitness of the atg7/lip5 double mutant. Comparative multi-omic analysis further revealed that the atg7/lip5 double mutant was strongly compromised in other chloroplast functions including photosynthesis and primary carbon metabolism. Premature senescence and reduced survival of atg/lip5 double mutants were associated with increased accumulation of reactive oxygen species and overactivation of stress-associated programs. Blocking PHYTOALEXIN DEFICIENT 4 and salicylic acid signaling prevented early senescence and death of the atg7/lip5 double mutant. Thus, stress-responsive autophagy and MVB pathways play an important cooperative role in protecting essential chloroplast functions including sulfur assimilation under normal growth conditions to suppress salicylic-acid-dependent premature cell-death and promote plant growth and fitness.

Wild vs. Cultivated Zingiber striolatum Diels: Nutritional and Biological Activity Differences

Compositional, functional, and nutritional properties are important for the use-value assessments of wild and cultivated edible plants. The aim of this study was to compare the nutritional composition, bioactive compounds, volatile compounds, and potential biological activities of cultivated and wild Zingiber striolatum. Various substances, such as soluble sugars, mineral elements, vitamins, total phenolics, total flavonoids, and volatiles, were measured and analyzed using UV spectrophotometry, ICP-OES, HPLC, and GC-MS methods. The antioxidant capacity of a methanol extract of Z. striolatum, as well as the hypoglycemic abilities of its ethanol and water extracts, were tested. The results showed that the contents of soluble sugar, soluble protein, and total saponin in the cultivated samples were higher, while the wild samples contained higher amounts of K, Na, Se, vitamin C, and total amino acids. The cultivated Z. striolatum also showed a higher antioxidant potential, while the wild Z. striolatum exhibited a better hypoglycemic activity. Thirty-three volatile compounds were identified using GC-MS in two plants, with esters and hydrocarbons being the main volatile compounds. This study demonstrated that both cultivated and wild Z. striolatum have a good nutritional value and biological activity, and can be used as a source of nutritional supplementation or even in medication.

Phenolic Content, Amino Acids, Volatile Compounds, Antioxidant Capacity, and Their Relationship in Wild Garlic (A. ursinum L.)

Allium ursinum L. is a wild relative of garlic, and it is abundant in many antioxidant compounds. Sulfur compounds, primarily cysteine sulfoxides (CSOs), are converted through several reactions into various volatile molecules, which are considered the principal flavor compounds of Alliums. In addition to secondary metabolites, wild garlic is abundant in primary compounds, such as amino acids, which serve not only as building blocks for the health-promoting sulfur compounds but also as antioxidants. The aim of this study was to investigate the link between individual amino acid contents, the total phenolic content, and the profile of volatile compounds as well as their influence on the antioxidant capacity of both the leaves and bulbs of wild garlic populations in Croatia. Both univariate and multivariate methods were used to study the differences in the phytochemical compositions among the wild garlic plant organs and the link between individual compounds and antioxidant capacity. Both the plant organ and location, as well as their interaction, have a significant impact on the content of total phenolic content, amino acids, volatile organic compounds, and the antioxidant capacity of wild garlic.

Phytoremediation as a way to clean technogenically polluted areas of Kazakhstan

One of the most serious problems worldwide is heavy metal (HM) pollution. HMs can have a toxic effect on human health and thus cause serious diseases. To date, several methods have been used to clean environments contaminated by HMs, but most of them are expensive, and it is difficult to achieve the desired result. Phytoremediation is currently an effective and affordable processing solution used to clean and remove HMs from the environment. This review article discusses in detail the technology of phytoremediation and mechanisms of HM absorption. In addition, methods are described using genetic engineering of various plants to enhance the resistance and accumulation of HMs. Thus, phytoremediation technology can become an additional aid to traditional methods of purification.