Comparative studies focusing on transgenic through cp4EPSPS gene and non-transgenic soybean plants: an analysis of protein species and enzymes

Proteomic and Metabolomic Evaluation of Insect- and Herbicide-Resistant Maize Seeds

Label-free quantitative proteomic (LFQ) and widely targeted metabolomic analyses were applied in the safety evaluation of three genetically modified (GM) maize varieties, BBL, BFL-1, and BFL-2, in addition to their corresponding non-GM parent maize. A total of 76, 40, and 25 differentially expressed proteins (DEPs) were screened out in BBL, BFL-1, and BFL-2, respectively, and their abundance compared was with that in their non-GM parents. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that most of the DEPs participate in biosynthesis of secondary metabolites, biosynthesis of amino acids, and metabolic pathways. Metabolomic analyses revealed 145, 178, and 88 differentially accumulated metabolites (DAMs) in the BBL/ZH58, BFL-1/ZH58, and BFL-2/ZH58×CH72 comparisons, respectively. KEGG pathway enrichment analysis showed that most of the DAMs are involved in biosynthesis of amino acids, and in arginine and proline metabolism. Three co-DEPs and 11 co-DAMs were identified in the seeds of these GM maize lines. The proteomic profiling of seeds showed that the GM maize varieties were not dramatically different from their non-GM control. Similarly, the metabolomic profiling of seeds showed no dramatic changes in the GM/non-GM maize varieties compared with the GM/GM and non-GM/non-GM maize varieties. The genetic background of the transgenic maize was found to have some influence on its proteomic and metabolomic profiles.

Proteomic Profile of Glyphosate-Resistant Soybean under Combined Herbicide and Drought Stress Conditions

While some genetically modified (GM) plants have been targeted to confer tolerance to abiotic stressors, transgenes are impacted by abiotic stressors, causing adverse effects on plant physiology and yield. However, routine safety analyses do not assess the response of GM plants under different environmental stress conditions. In the context of climate change, the combination of abiotic stressors is a reality in agroecosystems. Therefore, the aim of this study was to analyze the metabolic cost by assessing the proteomic profiles of GM soybean varieties under glyphosate spraying and water deficit conditions compared to their non-transgenic conventional counterparts. We found evidence of cumulative adverse effects that resulted in the reduction of enzymes involved in carbohydrate metabolism, along with the expression of amino acids and nitrogen metabolic enzymes. Ribosomal metabolism was significantly enriched, particularly the protein families associated with ribosomal complexes L5 and L18. The interaction network map showed that the affected module representing the ribosome pathway interacts strongly with other important proteins, such as the chloro-plastic gamma ATP synthase subunit. Combined, these findings provide clear evidence for increasing the metabolic costs of GM soybean plants in response to the accumulation of stress factors. First, alterations in the ribosome pathway indicate that the GM plant itself carries a metabolic burden associated with the biosynthesis of proteins as effects of genetic transformation. GM plants also showed an imbalance in energy demand and production under controlled conditions, which was increased under drought conditions. Identifying the consequences of altered metabolism related to the interaction between plant transgene stress responses allows us to understand the possible effects on the ecology and evolution of plants in the medium and long term and the potential interactions with other organisms when these organisms are released in the environment.

Proteomic analysis of the seeds of transgenic rice lines and the corresponding nongenetically modified isogenic variety

BACKGROUND

An isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analysis was employed to study the seeds of two genetically modified (GM) rice lines, T2A-1 and T1C-19, and their nontransgenic isogenic variety, MH63, to investigate the unintended effects of genetic modification.

RESULTS

A total of 3398 proteins were quantitatively identified. Seventy-seven differentially abundant proteins (DAPs) were identified in the T2A-1/MH63 comparison, and 70 and 7 of these DAPs were upregulated and downregulated, respectively. A pathway enrichment analysis showed that most of these DAPs participated in metabolic pathways and protein processing in endoplasmic reticulum and were ribosome components. Some 181 DAPs were identified from the T1C-19/MH63 comparison, and these included 115 upregulated proteins and 66 downregulated proteins. The subsequent pathway enrichment analysis showed that these DAPs mainly participated in protein processing in endoplasmic reticulum and carbon fixation in photosynthetic organisms and were ribosome components. None of these DAPs were identified as new unintended toxins or allergens, and only changes in abundance were detected. Fifty-four co-DAPs were identified in the seeds of the two GM rice lines, and protein-protein interaction analysis of these co-DAPs demonstrated that some interacting proteins were involved in protein processing in endoplasmic reticulum and metabolic pathways, whereas others were identified as ribosome components. Representative co-DAPs and proteins related to nutrients were analyzed using qRT-PCR to determine their transcriptional levels.

CONCLUSIONS

The results suggested that the seed proteomic profiles of the two GM rice lines studied were not substantially altered from those of their natural isogenic control. © 2020 Society of Chemical Industry.

Comparison of generational effect on proteins and metabolites in non-transgenic and transgenic soybean seeds through the insertion of the cp4-EPSPS gene assessed by omics-based platforms

This work evaluates different generations of transgenic (cp4-EPSPS gene) and non-transgenic soybean plants through proteomics and metabolomics. For proteomics purpose, 24 differentially abundant protein spots were found through 2-D DIGE, being 4 belonging to transgenic plants. From this total, 19 were successfully identified, storage proteins as predominant class. Some identified proteins are involved in growing and cell division, and stress response, such as LEA and dehydrin. For metabolomics, 17 compounds were putatively annotated, mainly belonging to the secondary metabolism, such as flavonoids. From these analyzes, all generations and varieties of the soybean are prone to be differentiate by PLS-DA. According to our results, transgenic plants appear to be more stable than non-transgenic ones. In addition, the omics-based approaches allowed access some relations between those differential spot proteins and metabolites, mainly those storage proteins and flavonoid.

iTRAQ-based quantitative proteomic analysis of two transgenic soybean lines and the corresponding non-genetically modified isogenic variety

To investigate the unintended effects of genetically modified (GM) crops, an isobaric tags for relative and absolute quantitation (iTRAQ)-based comparative proteomic analysis was performed with seed cotyledons of two GM soybean lines, MON87705 and MON87701×MON89788, and the corresponding non-transgenic isogenic variety A3525. Thirty-five differentially abundant proteins (DAPs) were identified in MON87705/A3525, 27 of which were upregulated and 8 downregulated. Thirty-eight DAPs were identified from the MON87701×MON89788/A3525 sample, including 29 upregulated proteins and 9 downregulated proteins. Pathway analysis showed that most of these DAPs participate in protein processing in endoplasmic reticulum and in metabolic pathways. Protein-protein interaction analysis of these DAPs demonstrated that the main interacting proteins are associated with post-translational modification, protein turnover, chaperones and signal transduction mechanisms. Nevertheless, these DAPs were not identified as new unintended toxins or allergens and only showed changes in abundance. All these results suggest that the seed cotyledon proteomic profiles of the two GM soybean lines studied were not dramatically altered compared with that of their natural isogenic control.

Evaluation of some effects on plant metabolism through proteins and enzymes in transgenic and non-transgenic soybeans after cultivation with silver nanoparticles

To evaluate the effects of silver nanoparticles (AgNP) exposition, transgenic (through gene cp4EPSPS) and non-isogenic non-transgenic soybeans were cultivated in the presence or absence of AgNP or silver nitrate (AgNO3) at 50 mg/kg of silver. Physiological aspects of the plants including mass production and development of roots, proteomics such as protein amount and differential proteins, enzymes and lipid peroxidation were determined after exposition. The mass production of non-transgenic plants treated with AgNP or AgNO3 was decreased by 25 and 19%, respectively, on their mass based, while for transgenic soybean this effect was observed for AgNP cultivation only. Fifty-nine proteins were identified from the differentially abundant spots by two-dimensional difference gel electrophoresis and nano-electrospray ionization liquid chromatography coupled tandem mass spectrometry. Identified species as ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), ATP synthase, superoxide dismutase (SOD), related to plant metabolism were less abundant for the cultivation with either AgNP and AgNO3 than the control. Finally, this work demonstrated significant correlation as evidenced by changes in lipid peroxidation content and catalase activity, which were a result of exposure to either AgNP or AgNO3 cultivations. Further, necrotic areas in the basal part of the stems and damage or chlorotic areas were found in the leaves. SIGNIFICANCE: Once nanoparticles have been employed for several applications in recent years and they can be released in the environmental matrices, this study highlights proteomic and enzymatic alterations in transgenic and non-transgenic soybeans, an important crop, after cultivation with silver nanoparticles. Such strategy employing proteomic and enzymatic approaches to evaluate soybeans exposed to silver nanoparticles has not yet been reported. Therefore, the results obtained in this study can expand the information concerning the effects of silver nanoparticles in soybean plants.

Reply to 'Comments on two recent publications on GM maize and Roundup'

The opinion expressed by Eriksson and colleagues' fails to recognise that there are no standard experimental designs for academic investigations involving omics analyses of genetically modified crops and that the only valid comparator to determine the effect of the process of transgenesis is a near isogenic variety grown at the same time and location, as was the case in our investigation of NK603 maize. Eriksson does not acknowledge that the quality of the rat liver tissues in our chronic Roundup toxicity study has neither been questioned nor branded as unsuitable for further investigation. In addition, Eriksson fails to appreciate that the statistical methods we used to analyse the liver metabolomics dataset are recognised as appropriate as some of a number of approaches that can be taken. Moreover, Eriksson neglects to mention that the proteomics analysis of the liver tissues highlights structural and functional damage from Roundup exposure. Thus our results are sound and the claims by Eriksson and colleagues of experimental flaws are unfounded.Replying to: Eriksson et al. Sci Rep 8 (2018); https://doi.org/10.1038/s41598-018-30440-7 .

Evaluation of changes in the macro and micronutrients homeostasis of transgenic and non-transgenic soybean plants after cultivation with silver nanoparticles through ionomic approaches

An ionomic approach is conducted for evaluating the silver distribution, in different soybean plant compartments, as well as its influence on the homeostasis of some macro (P and S) and micro (Cu, Fe, Mn and Zn) nutrients. Silver is added to transgenic and non-transgenic soybean plants as nanoparticles or silver nitrate for comparative purposes. The transgenic plants translocate a higher amount of silver (100 and 65% for silver nanoparticles and silver nitrate expositions, respectively) than non-transgenic, and considering the treatments, the cultivation with silver nanoparticles results in a higher translocation rate (100 and 21% for transgenic and non-transgenic plants, respectively). In addition, significant differences are found (p < 0.05) considering those macro and micronutrients in all plant compartments, mainly in the roots of those treated plants, indicating not only that both silver forms evaluated interfere in the plant metabolism, but also their toxicities.

Changes in Amino Acid Profile in Roots of Glyphosate Resistant and Susceptible Soybean (Glycine max) Induced by Foliar Glyphosate Application

Amino acid profiles are useful to analyze the responses to glyphosate in susceptible and resistant soybean lines. Comparisons of profiles for 10 amino acids (Asp, Asn, Glu, Gln, Ser, His, Gly, Thr, Tyr, Leu) by HPLC in soybean roots were performed in two near isogenic pairs (four varieties). Foliar application of glyphosate was made to soybean plants after 5 weeks of seeding. Roots of four varieties were collected at 0 and 72 h after glyphosate application (AGA) for amino acid analysis by HPLC. Univariate analysis showed a significant increase of several amino acids in susceptible as well as resistant soybean lines; however, amino acids from the major pathways of carbon (C) and nitrogen (N) metabolism, such as Asp, Asn, Glu and Gln, and Ser, increased significantly in susceptible varieties at 72 h AGA. Multivariate analysis using principal component analysis (2D PCA and 3D PCA) allowed different groups to be identified and discriminated based on the soybean genetic origin, showing the amino acid responses on susceptible and resistant varieties. Based on the results, it is possible to infer that the increase of Asn, Asp, Glu, Gln, and Ser in susceptible varieties would be related to the deregulation of C and N metabolism, as well as changes in the growth mechanisms regulated by Ser.

Proteomic analysis of phytase transgenic and non-transgenic maize seeds

Proteomics has become a powerful technique for investigating unintended effects in genetically modified crops. In this study, we performed a comparative proteomics of the seeds of phytase-transgenic (PT) and non-transgenic (NT) maize using 2-DE and iTRAQ techniques. A total of 148 differentially expressed proteins (DEPs), including 106 down-regulated and 42 up-regulated proteins in PT, were identified. Of these proteins, 32 were identified through 2-DE and 116 were generated by iTRAQ. It is noteworthy that only three proteins could be detected via both iTRAQ and 2-DE, and most of the identified DEPs were not newly produced proteins but proteins with altered abundance. These results indicated that many DEPs could be detected in the proteome of PT maize seeds and the corresponding wild type after overexpression of the target gene, but the changes in these proteins were not substantial. Functional classification revealed many DEPs involved in posttranscriptional modifications and some ribosomal proteins and heat-shock proteins that may generate adaptive effects in response to the insertion of exogenous genes. Protein-protein interaction analysis demonstrated that the detected interacting proteins were mainly ribosomal proteins and heat-shock proteins. Our data provided new information on such unintended effects through a proteomic analysis of maize seeds.

In vitro oral bioaccessibility and total content of Cu, Fe, Mn and Zn from transgenic (through cp4 EPSPS gene) and nontransgenic precursor/successor soybean seeds

In this paper, Cu, Fe, Mn and Zn contents in transgenic (T - MSOY7122RR) and non-transgenic (NT - MSOY8200) soybean seeds, sown at summer and winter cultivation periods are investigated using four microwave decomposition methods. Student's t tests demonstrate significant differences (p=0.05; n=4), for Cu, Mn and Zn (namely, 8, 9 and 26% higher concentrations in T compared to NT seeds, respectively). Through principal component analysis, precursor and successor soybean seeds are identified. Cu is demonstrated to play an important role in the differentiation of the cultivars, whereas Fe and Zn are of particular relevance in the classification of seeds cultivated in winter against those in summer. Using in vitro extraction based on the Unified Bioaccessibility Method, the bioaccessibility of the above nutrients is proven to differ in both the gastric and gastrointestinal phases on the basis of the transgenesis and the cultivation periods.

Glyphosate Can Decrease Germination of Glyphosate-Resistant Soybeans

We investigated the effects of different concentrations of glyphosate acid and one of its formulations (Roundup) on seed germination of two glyphosate-resistant (GR) and one non-GR variety of soybean. As expected, the herbicide affected the shikimate pathway in non-GR seeds but not in GR seeds. We observed that glyphosate can disturb the mitochondrial electron transport chain, leading to H2O2 accumulation in soybean seeds, which was, in turn, related to lower seed germination. In addition, GR seeds showed increased activity of antioxidant systems when compared to non-GR seeds, making them less vulnerable to oxidative stress induced by glyphosate. The differences in the responses of GR varieties to glyphosate exposure corresponded to their differences in enzymatic activity related to H2O2 scavenging and mitochondrial complex III (the proposed site of ROS induction by glyphosate). Our results showed that glyphosate ought to be used carefully as a pre-emergence herbicide in soybean field crop systems because this practice may reduce seed germination.

Abscisic acid-deficient sit tomato mutant responses to cadmium-induced stress

There is a very effective cross-talk between signals triggered by reactive oxygen species and hormonal responses in plants, activating proteins/enzymes likely to be involved in stress tolerance. Abscisic acid (ABA) is known as a stress hormone that takes part in the integration of signals. This work aimed to characterize the biochemical response and ultrastructural changes induced by cadmium (Cd) in the Micro-Tom (MT) sitiens ABA-deficient mutant (sit) and its wild-type (MT) counterpart. MT and sit plants were grown over a 96-h period in the presence of Cd (0, 10, and 100 μM CdCl₂). The overall results indicated increases in lipid peroxidation, hydrogen peroxide content and in the activities of the key antioxidant enzymes such as catalase, glutathione reductase, and ascorbate peroxidase in both genotypes. On the other hand, no alteration was observed in chlorophyll content, while the activity of another antioxidant enzyme, superoxide dismutase, remained constant or even decreased in the presence of Cd. Roots and shoots of the sit mutant and MT were analyzed by light and transmission electron microscopy in order to characterize the structural changes caused by the exposure to this metal. Cd caused a decrease in intercellular spaces in shoots and a decrease in cell size in roots of both genotypes. In leaves, Cd affected organelle shape and internal organization of the thylakoid membranes, whereas noticeable increase in the number of mitochondria and vacuoles in MT and sit roots were observed. These results add new information that should help unravel the relative importance of ABA in regulating the cell responses to stressful conditions induced by Cd apart from providing the first characterization of this mutant to oxidative stress.

An integrated multi-omics analysis of the NK603 Roundup-tolerant GM maize reveals metabolism disturbances caused by the transformation process

Glyphosate tolerant genetically modified (GM) maize NK603 was assessed as 'substantially equivalent' to its isogenic counterpart by a nutrient composition analysis in order to be granted market approval. We have applied contemporary in depth molecular profiling methods of NK603 maize kernels (sprayed or unsprayed with Roundup) and the isogenic corn to reassess its substantial equivalence status. Proteome profiles of the maize kernels revealed alterations in the levels of enzymes of glycolysis and TCA cycle pathways, which were reflective of an imbalance in energy metabolism. Changes in proteins and metabolites of glutathione metabolism were indicative of increased oxidative stress. The most pronounced metabolome differences between NK603 and its isogenic counterpart consisted of an increase in polyamines including N-acetyl-cadaverine (2.9-fold), N-acetylputrescine (1.8-fold), putrescine (2.7-fold) and cadaverine (28-fold), which depending on context can be either protective or a cause of toxicity. Our molecular profiling results show that NK603 and its isogenic control are not substantially equivalent.

Comparative Proteomics of Leaves from Phytase-Transgenic Maize and Its Non-transgenic Isogenic Variety

To investigate unintended effects in genetically modified crops (GMCs), a comparative proteomic analysis between the leaves of the phytase-transgenic maize and the non-transgenic plants was performed using two-dimensional gel electrophoresis and mass spectrometry. A total of 57 differentially expressed proteins (DEPs) were successfully identified, which represents 44 unique proteins. Functional classification of the identified proteins showed that these DEPs were predominantly involved in carbohydrate transport and metabolism category, followed by post-translational modification. KEGG pathway analysis revealed that most of the DEPs participated in carbon fixation in photosynthesis. Among them, 15 proteins were found to show protein-protein interactions with each other, and these proteins were mainly participated in glycolysis and carbon fixation. Comparison of the changes in the protein and tanscript levels of the identified proteins showed that most proteins had a similar pattern of changes between proteins and transcripts. Our results suggested that although some significant differences were observed, the proteomic patterns were not substantially different between the leaves of the phytase-transgenic maize and the non-transgenic isogenic type. Moreover, none of the DEPs was identified as a new toxic protein or an allergenic protein. The differences between the leaf proteome might be attributed to both genetic modification and hybrid influence.

Proteomic analysis of mature barley grains from C-hordein antisense lines

Hordeins are the major storage proteins in barley grains and are responsible for their low nutritional quality. Previously, antisense C-hordein barley lines were generated and were shown to contain a more balanced amino acid composition and an altered storage protein profile. In the present study, a proteomic approach that combined two-dimensional gel electrophoresis (2-DE) and mass spectrometry was used to (1) identify the changes in the protein profile of non-storage proteins (salt soluble fraction) in antisense C-hordein barley lines (L1, L2 and L3) and (2) map the differentially expressed proteins compared to the non-transgenic control line (Hordeum vulgare cv. Golden Promise). Moreover, the changes in the proteins were correlated with the more balanced amino acid composition of these lines, with special attention to the lysine content. The results showed that suppression of C-hordein expression does not exclusively affect hordein synthesis and accumulation. The more balanced amino acid composition observed in the transgenic lines L1, L2 and L3 was an indirect result of the profound alterations in the patterns of the non-storage proteins. The observed changes included up-regulated expression of the proteins involved in stress and detoxification (L1), defence (L2 and L3), and storage globulins (L1, L2 and L3). To a lesser extent, the proteins involved in grain metabolism were also changed. Thus, the increased essential amino acids content results from changes in distinct protein sources among the three antisense C-hordein lines analyzed, although the up-regulated expression of lysine-rich proteins was consistently observed in all lines.

Evaluation of proteome alterations induced by cadmium stress in sunflower (Helianthus annuus L.) cultures

The present study evaluates, at a proteomic level, changes in protein abundance in sunflower leaves in the absence or presence (at 50 or 700mg) of cadmium (as CdCl2). At the end of the cultivation period (45 days), proteins are extracted from leaves with phenol, separated by two-dimensional difference gel electrophoresis (2-D DIGE), and excised from the gels. The differential protein abundances (for proteins differing by more than 1.8 fold, which corresponds to 90% variation) are characterized using nESI-LC-MS/MS. The protein content decreases by approximately 41% in plants treated with 700mg Cd compared with control plants. By comparing all groups of plants evaluated in this study (Control vs. Cd-lower, Control vs. Cd-higher and Cd-lower vs. Cd-higher), 39 proteins are found differential and 18 accurately identified; the control vs. Cd-higher treatment is that presenting the most differential proteins. From identified proteins, those involved in energy and disease/defense (including stress), are the ribulose bisphosphate carboxylase large chain, transketolase, and heat shock proteins are the most differential abundant proteins. Thus, at the present study, photosynthesis is the main process affected by Cd in sunflowers, although these plants are highly tolerant to Cd.

Evaluation of protein extraction methods for enhanced proteomic analysis of tomato leaves and roots

Proteomics is an outstanding area in science whose increasing application has advanced to distinct purposes. A crucial aspect to achieve a good proteome resolution is the establishment of a methodology that results in the best quality and wide range representation of total proteins. Another important aspect is that in many studies, limited amounts of tissue and total protein in the tissue to be studied are found, making difficult the analysis. In order to test different parameters, combinations using minimum amount of tissue with 4 protocols for protein extraction from tomato (Solanum lycopersicum L.) leaves and roots were evaluated with special attention to their capacity for removing interferents and achieving suitable resolution in bidimensional gel electrophoresis, as well as satisfactory protein yield. Evaluation of the extraction protocols revealed large protein yield differences obtained for each one. TCA/acetone was shown to be the most efficient protocol, which allowed detection of 211 spots for leaves and 336 for roots using 500 µg of leaf protein and 800 µg of root protein per gel.

Tropical soils with high aluminum concentrations cause oxidative stress in two tomato genotypes

Tropical and subtropical soils are usually acidic and have high concentrations of aluminum (Al). Aluminum toxicity in plants is caused by the high affinity of the Al cation for cell walls, membranes, and metabolites. In this study, the response of the antioxidant-enzymatic system to Al was examined in two tomato genotypes: Solanum lycopersicum var. esculentum (Calabash Rouge) and Solanum lycopersicum var. cerasiforme (CNPH 0082) grown in tropical soils with varying levels of Al. Plant growth; activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPOX), and glutathione reductase (GR) enzymes; stress-indicating compounds (malondialdehyde (MDA) and hydrogen peroxide); and morphology (root length and surface area) were analyzed. Increased levels of Al in soils were correlated with reduced shoot and root biomass and with reduced root length and surface area. Calabash Rouge exhibited low Al concentrations and increased growth in soils with the highest levels of Al. Plants grown in soils with high availability of Al exhibited higher levels of stress indicators (MDA and hydrogen peroxide) and higher enzyme activity (CAT, APX, GPOX, and GR). Calabash Rouge absorbed less Al from soils than CNPH 0082, which suggests that the genotype may possess mechanisms for Al tolerance.

A transcriptomic analysis for identifying the unintended effects of introducing a heterologous glyphosate-tolerant EPSP synthase into Escherichia coli

Glyphosate is one of the most commonly used broad-spectrum herbicides with little to no hazard to animals, human beings, or the environment. Some microbial 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase variants are not inhibited by glyphosate, and they provide a powerful tool to engineer glyphosate-tolerant plants. However, the unintended effects of EPSP synthase expression patterns on microbes are not yet clear. Here, we use an Affymetrix GeneChip analysis to study how introduction of a heterologous glyphosate-tolerant EPSP synthase into a model microorganism Escherichia coli (E. coli) affects the global gene expression profile. The profile showed that 161 of 4071 genes were differentially expressed after the introduction of the synthase: 19 (0.47%) were up-regulated and 143 (3.49%) were down-regulated. The microarray results, in combination with BiOLOG substrate utilization and amino acid composition assays, suggested that heterologous EPSP synthase expression had very minor effects on E. coli. Although a small number of genes and metabolites were affected by EPSP synthase expression, no functional correlations were identified among the dataset. This study may shed light on the effect of EPSP synthase expression on microbes, which should help in the assessment of environmental safety.

Comparative proteomics and metallomics studies in Arabidopsis thaliana leaf tissues: evaluation of the selenium addition in transgenic and nontransgenic plants using two-dimensional difference gel electrophoresis and laser ablation imaging

The main goal of this work is to evaluate some differential protein species in transgenic (T) and nontransgenic (NT) Arabidopsis thaliana plants after their cultivation in the presence or absence of sodium selenite. The transgenic line was obtained through insertion of CaMV 35S controlling nptII gene. Comparative proteomics through 2D-DIGE is carried out in four different groups (NT × T; NT × Se-NT (where Se is selenium); Se-NT × Se-T, and T × Se-T). Although no differential proteins are achieved in the T × Se-T group, for the others, 68 differential proteins (by applying a regulation factor ≥1.5) are achieved, and 27 of them accurately characterized by ESI-MS/MS. These proteins are classified into metabolism, energy, signal transduction, disease/defense categories, and some of them are involved in the glycolysis pathway-Photosystems I and II and ROS combat. Additionally, laser ablation imaging is used for evaluating the Se and sulfur distribution in leaves of different groups, corroborating some results obtained and related to proteins involved in the glycolysis pathway. From these results, it is possible to conclude that the genetic modification also confers to the plant resistance to oxidative stress.

Evaluation of Fe uptake and translocation in transgenic and non-transgenic soybean plants using enriched stable (57)Fe as a tracer

A tracer experiment is carried out with transgenic T (variety M 7211 RR) and non-transgenic NT (variety MSOY 8200) soybean plants to evaluate if genetic modification can influence the uptake and translocation of Fe. A chelate of EDTA with enriched stable (57)Fe is applied to the plants cultivated in vermiculite plus substrate and the (57)Fe acts as a tracer. The exposure of plants to enriched (57)Fe causes the dilution of the natural previously existing Fe in the plant compartments and then the changed Fe isotopic ratio ((57)Fe/(56)Fe) is measured using a quadrupole-based inductively coupled plasma mass spectrometer equipped with a dynamic reaction cell (DRC). Mathematical calculations based on the isotope dilution methodology allow distinguishing the natural abundance Fe from the enriched Fe (incorporated during the experiment). The NT soybean plants acquire higher amounts of Fe from natural abundance (originally present in the soil) and from enriched Fe (coming from the (57)Fe-EDTA during the experiment) than T soybean ones, demonstrating that the NT soybean plants probably absorb higher amounts of Fe, independently of the source. The percentage of newly incorporated Fe (coming from the treatment) was approximately 2.0 and 1.1% for NT and T soybean plants, respectively. A higher fraction (90.1%) of enriched Fe is translocated to upper parts, and a slightly lower fraction (3.8%) is accumulated in the stems by NT plants than by T ones (85.1%; 5.1%). Moreover, in both plants, the Fe-EDTA facilitates the transport and translocation of Fe to the leaves. The genetic modification is probably responsible for differences observed between T and NT soybean plants.