The glutathione S-transferase gene superfamily: an in silico approach to study the post translational regulation

Biochemical and molecular responses of the ascorbate-glutathione cycle in wheat seedlings exposed to different forms of selenium

Biofortification aims to increase selenium (Se) concentration and bioavailability in edible parts of crops such as wheat (Triticum aestivum L.), resulting in increased concentration of Se in plants and/or soil. Higher Se concentrations can disturb protein structure and consequently influence glutathione (GSH) metabolism in plants which can affect antioxidative and other detoxification pathways. The aim of this study was to elucidate the impact of five different concentrations of selenate and selenite (0.4, 4, 20, 40 and 400 mg kg-1) on the ascorbate-glutathione cycle in wheat shoots and roots and to determine biochemical and molecular tissue-specific responses. Content of investigated metabolites, activities of detoxification enzymes and expression of their genes depended both on the chemical form and concentration of the applied Se, as well as on the type of plant tissue. The most pronounced changes in the expression level of genes involved in GSH metabolism were visible in wheat shoots at the highest concentrations of both forms of Se. Obtained results can serve as a basis for further research on Se toxicity and detoxification mechanisms in wheat. New insights into the Se impact on GSH metabolism could contribute to the further development of biofortification strategies.

Hub Genes and Pathways Related to Lemon (Citrus limon) Leaf Response to Plenodomus tracheiphilus Infection and Influenced by Pseudomonas mediterranea Biocontrol Activity

The lemon industry in the Mediterranean basin is strongly threatened by "mal secco" disease (MSD) caused by the fungus Plenodomus tracheiphlilus. Leaf pretreatments with Pseudomonas mediterranea 3C have been proposed as innovative tools for eco-sustainable interventions aimed at controlling the disease. In this study, by exploiting the results of previously performed RNAseq analysis, WCGNA was conducted among gene expression patterns in both inoculated (Pt) and pretreated and fungus-inoculated lemon plants (Citrus limon L.) (3CPt), and two indicators of fungal infection, i.e., the amount of fungus DNA measured in planta and the disease index (DI). The aims of this work were (a) to identify gene modules significantly associated with those traits, (b) to construct co-expression networks related to mal secco disease; (c) to define the effect and action mechanisms of P. mediterranea by comparing the networks. The results led to the identification of nine hub genes in the networks, with three of them belonging to receptor-like kinases (RLK), such as HERK1, CLAVATA1 and LRR, which play crucial roles in plant-pathogen interaction. Moreover, the comparison between networks indicated that the expression of those receptors is not induced in the presence of P. mediterranea, suggesting how powerful WCGNA is in discovering crucial genes that must undergo further investigation and be eventually knocked out.

Transcriptomic profile of lettuce seedlings (Lactuca sativa) response to microalgae extracts used as biostimulant agents

To reduce the use of chemical fertilizers and maximize agricultural yields, the use of microalgae extracts as biostimulants has recently attracted significant attention due to their favourable impact on both plant growth and their ability to induce tolerance towards environmental stressors. Lettuce (Lactuca sativa) is one of the most important fresh vegetables that often requires applications of chemical fertilizers to increase quality and productivity. Accordingly, the purpose of this study was to analyse the transcriptome reprogramming of lettuce (L. sativa) seedlings in response to either Chlorella vulgaris or Scenedesmus quadricauda extracts by applying an RNAseq approach. Differential gene expression analysis revealed that the core gene set that responded to microalgal treatments in a species-independent manner includes 1330 clusters, 1184 of which were down-regulated and 146 up-regulated, clearly suggesting that the repression of gene expression is the main effect of algal treatments. The deregulation of 7197 transcripts in the C. vulgaris treated seedlings compared to control samples (LsCv vs. LsCK) and 7118 transcripts in the S. quadricauda treated seedlings compared to control samples (LsSq vs. LsCK) were counted. Although the number of deregulated genes turned out to be similar between the algal treatments, the level of deregulation was higher in LsCv versus LsCK than in LsSq versus LsCK. In addition, 2439 deregulated transcripts were observed in the C. vulgaris treated seedlings compared to S. quadricauda treated samples (LsCv vs. LsSq comparison) suggesting that a specific transcriptomic profile was induced by the single algal extracts. 'Plant hormone signal transduction' category includes a very elevated number of DEGs, many of them specifically indicating that C. vulgaris actives both genes involved in the auxin biosynthesis and transduction pathways, whereas S. quadricauda up-regulates genes implicated in the cytokinin biosynthesis pathway. Finally, algal treatments induced the deregulation of genes encoding small hormone-like molecules that are known to act alone or by interacting with major plant hormones. In conclusion, this study offers the groundwork to draw up a list of putative gene targets with the aim of lettuce genetic improvement that will allow a limited or even null use of synthetic fertilizers and pesticides in the management of this crop.

Genome-wide identification and characterization of Glutathione S-Transferases (GSTs) and their expression profile under abiotic stresses in tobacco (Nicotiana tabacum L.)

BACKGROUND

Glutathione S-transferases (GSTs) are large and multifunctional proteases that play an important role in detoxification, protection against biotic and abiotic stresses, and secondary metabolite transportation which is essential for plant growth and development. However, there is limited research on the identification and function of NtGSTs.

RESULTS

This study uses K326 and other six tobacco varieties (Hongda, HG, GDH11, Va116, VG, and GDH88) as materials to conduct comprehensive genome-wide identification and functional characterization of the GST gene in tobacco. A total of 59 NtGSTs were identified and classified into seven subfamilies via the whole-genome sequence analysis, with the Tau type serving as the major subfamily. The NtGSTs in the same branch of the evolutionary tree had similar exon/intron structure and motif constitution. There were more than 42 collinear blocks between tobacco and pepper, tomato, and potato, indicating high homology conservation between them. Twelve segmental duplicated gene pairs and one tandem duplication may have had a substantial impact on the evolution and expansion of the tobacco GST gene family. The RT-qPCR results showed that the expression patterns of NtGSTs varied significantly among tissues, varieties, and multiple abiotic stresses, suggesting that NtGST genes may widely respond to various abiotic stresses and hormones in tobacco, including NtGSTF4, NtGSTL1, NtGSTZ1, and NtGSTU40.

CONCLUSIONS

This study provides a comprehensive analysis of the NtGST gene family, including structures and functions. Many NtGSTs play a critical regulatory role in tobacco growth and development, and responses to abiotic stresses. These findings offer novel and valuable insights for understanding the biological function of NtGSTs and the reference materials for cultivating highly resistant varieties and enhancing the yield and quality of crops.

Genome-wide identification and characterization of glutathione S-transferase gene family in Musa acuminata L. AAA group and gaining an insight to their role in banana fruit development

Glutathione S-transferases are a multifunctional protein superfamily that is involved in diverse plant functions such as defense mechanisms, signaling, stress response, secondary metabolism, and plant growth and development. Although the banana whole-genome sequence is available, the distribution of GST genes on banana chromosomes, their subcellular localization, gene structure, their evolutionary relation with each other, conserved motifs, and their roles in banana are still unknown. A total of 62 full-length GST genes with the canonical thioredoxin fold have been identified belonging to nine GST classes, namely tau, phi, theta, zeta, lambda, DHAR, EF1G, GHR, and TCHQD. The 62 GST genes were distributed into 11 banana chromosomes. All the MaGSTs were majorly localized in the cytoplasm. Gene architecture showed the conservation of exon numbers in individual GST classes. Multiple Em for Motif Elicitation analyses revealed few class-specific motifs and many motifs were found in all the GST classes. Multiple sequence alignment of banana GST amino acid sequences with rice, Arabidopsis, and soybean sequences revealed the Ser and Cys as conserved catalytic residues. Gene duplication analyses showed the tandem duplication as a driving force for GST gene family expansion in banana. Cis-regulatory element analysis showed the dominance of light-responsive element followed by stress- and hormone-responsive elements. Expression profiling analyses were also done by RNA-seq data. It was observed that MaGSTs are involved in various stages of fruit development. MaGSTU1 was highly upregulated. The comprehensive and organized studies of MaGST gene family provide groundwork for further functional analysis of MaGST genes in banana at molecular level and further for plant breeding approaches.

Global leaf and root transcriptome in response to cadmium reveals tolerance mechanisms in Arundo donax L

The expected increase of sustainable energy demand has shifted the attention towards bioenergy crops. Due to their know tolerance against abiotic stress and relatively low nutritional requirements, they have been proposed as election crops to be cultivated in marginal lands without disturbing the part of lands employed for agricultural purposes. Arundo donax L. is a promising bioenergy crop whose behaviour under water and salt stress has been recently studied at transcriptomic levels. As the anthropogenic activities produced in the last years a worrying increase of cadmium contamination worldwide, the aim of our work was to decipher the global transcriptomic response of A. donax leaf and root in the perspective of its cultivation in contaminated soil. In our study, RNA-seq libraries yielded a total of 416 million clean reads and 10.4 Gb per sample. De novo assembly of clean reads resulted in 378,521 transcripts and 126,668 unigenes with N50 length of 1812 bp and 1555 bp, respectively. Differential gene expression analysis revealed 5,303 deregulated transcripts (3,206 up- and 2,097 down regulated) specifically observed in the Cd-treated roots compared to Cd-treated leaves. Among them, we identified genes related to “Protein biosynthesis”, “Phytohormone action”, “Nutrient uptake”, “Cell wall organisation”, “Polyamine metabolism”, “Reactive oxygen species metabolism” and “Ion membrane transport”. Globally, our results indicate that ethylene biosynthesis and the downstream signal cascade are strongly induced by cadmium stress. In accordance to ethylene role in the interaction with the ROS generation and scavenging machinery, the transcription of several genes (NADPH oxidase 1, superoxide dismutase, ascorbate peroxidase, different glutathione S-transferases and catalase) devoted to cope the oxidative stress is strongly activated. Several small signal peptides belonging to ROTUNDIFOLIA, CLAVATA3, and C-TERMINALLY ENCODED PEPTIDE 1 (CEP) are also among the up-regulated genes in Cd-treated roots functioning as messenger molecules from root to shoot in order to communicate the stressful status to the upper part of the plants. Finally, the main finding of our work is that genes involved in cell wall remodelling and lignification are decisively up-regulated in giant reed roots. This probably represents a mechanism to avoid cadmium uptake which strongly supports the possibility to cultivate giant cane in contaminated soils in the perspective to reserve agricultural soil for food and feed crops.

De Novo Transcriptome Sequencing of Rough Lemon Leaves (Citrus jambhiri Lush.) in Response to Plenodomus tracheiphilus Infection

Mal secco is one of the most severe diseases of citrus, caused by the necrotrophic fungus Plenodomus tracheiphilus. With the main aim of identifying candidate genes involved in the response of citrus plants to "Mal secco", we performed a de novo transcriptome analysis of rough lemon seedlings subjected to inoculation of P. tracheiphilus. The analysis of differential expressed genes (DEGs) highlighted a sharp response triggered by the pathogen as a total of 4986 significant DEGs (2865 genes up-regulated and 2121 down-regulated) have been revealed. The analysis of the most significantly enriched KEGG pathways indicated that a crucial role is played by genes involved in "Plant hormone signal transduction", "Phenylpropanoid biosynthesis", and "Carbon metabolism". The main findings of this work are that under fungus challenge, the rough lemon genes involved both in the light harvesting and the photosynthetic electron flow were significantly down-regulated, thus probably inducing a shortage of energy for cellular functions. Moreover, the systemic acquired resistance (SAR) was activated through the induced salicylic acid cascade. Interestingly, RPM1 interacting protein 4, an essential positive regulator of plant defense, and BIR2, which is a negative regulator of basal level of immunity, have been identified thus representing useful targets for molecular breeding.

Transcriptional response of giant reed (Arundo donax L.) low ecotype to long-term salt stress by unigene-based RNAseq

The giant reed is a fast growing herbaceous non-food crop considered as eligible alternative energy source to reduce the usage of fossil fuels. Tolerance of this plant to abiotic stress has been demonstrated across a range of stressful conditions, thus allowing cultivation in marginal or poorly cultivated land in order not to compromise food security and to overcome land use controversies. In this work, we de novo sequenced, assembled and analyzed the A. donax low G34 ecotype leaf transcriptome (RNAseq analysis) subjected to severe long-term salt stress (256.67 mM NaCl corresponding to 32 dS m^-1 electric conductibility). In order to shed light upon the response to high salinity of this non model plant, we analyzed clusters related to salt sensory and signaling transduction, transcription factors, hormone regulation, Reactive Oxygen Species (ROS) scavenging and osmolyte biosynthesis, all of them showing different regulation compared to untreated plants. The analysis of clusters related to ethylene biosynthesis and signaling indicated that gene transcription is modulated towards the minimization of ethylene negative effects upon plant growth. Certainly, the photosynthesis is strongly affected since genes involved in Rubisco biosynthesis and assembly are down-regulated. However, a shift towards C4 photosynthesis is likely to occur as gene regulation is aimed to activate the primary CO₂ fixation to PEP (phosphoenolpyruvate). The analysis of "carbon metabolism" category revealed that G34 ecotype under salt stress induces the expression of glycolysis and Krebs cycle related genes, this being consistent with the hypothesis that some sort of salt avoidance might be occurred in A. donax G34 low ecotype. By comparing our results with findings obtained with other giant reed ecotype, we identified several differences in the response to salt that are in accordance with the possibility that heritable phenotypic differences among clones of A. donax might be accumulated especially in ecotypes originating from distant geographical areas, despite their asexual reproduction modality. Additionally, 26,838 simple sequence repeat (SSR) markers were identified and validated. This SSR dataset definitely expands the marker catalogue of A. donax facilitating the genotypic characterization of this species.

Glutathione S-transferase: a versatile protein family

Glutathione-S transferase (GST) is a most ancient protein superfamily of multipurpose roles and evolved principally from gene duplication of an ancestral GSH binding protein. They have implemented in diverse plant functions such as detoxification of xenobiotic, secondary metabolism, growth and development, and majorly against biotic and abiotic stresses. The vital structural features of GSTs like highly divergent functional topographies, conserved integrated architecture with separate binding pockets for substrates and ligand, the stringent structural fidelity with high Tm values (50º-60º), and stress-responsive cis-regulatory elements in the promoter region offer this protein as most flexible plant protein for plant breeding approaches, biotechnological applications, etc. This review article summarizes the recent information of GST evolution, and their distribution and structural features with emphasis on the assorted roles of Ser and Cys GSTs with the signature motifs in their active sites, alongside their recent biotechnological application in the area of agriculture, environment, and nanotechnology have been highlighted.

Genome-wide identification of the glutathione transferase superfamily in the model organism Brachypodium distachyon

The detoxification of harmful metabolites can determine the effectiveness of plant stress responses. Scavenging some of these toxic stress by-products through the reduced form of glutathione is catalysed by members of the glutathione transferase (GST) enzyme superfamily. The involvement of these enzymes was studied in the model organism Brachypodium distachyon (L.)P.Beauv. Bd21 and in its derivative Bd21-3, a more drought tolerant line. Osmotic stress treatment resulted in a decrease in the water potential of both Brachypodium genotypes, the difference between the control and treated plant's ψw decreased by the last sampling day in Bd21-3, suggesting some degree of adaptation to the applied osmotic stress. Increased GST activity revealed a severe defence reaction against the harmful imbalance of the redox environment. Screening for the gene sequences led to the identification of 91 full-length or partial GST sequences. Although purple false brome has a relatively small genome, the number of identified GST genes was almost as high as the number predicted in wheat. The estimation of GST expression showed stress-induced differences: higher expression levels or the fast induction of BdGSTF8, BdGSTU35 and BdGSTU42 gene products presumably indicate a strong detoxification under osmotic stress.

RNASeq analysis of giant cane reveals the leaf transcriptome dynamics under long-term salt stress

BACKGROUND

To compensate for the lack of information about the molecular mechanism involved in Arundo donax L. response to salt stress, we de novo sequenced, assembled and analyzed the A. donax leaf transcriptome subjected to two levels of long-term salt stress (namely, S3 severe and S4 extreme).

RESULTS

The picture that emerges from the identification of differentially expressed genes is consistent with a salt dose-dependent response. Hence, a deeper re-programming of the gene expression occurs in those plants grew at extreme salt level than in those subjected to severe salt stress, probably representing for them an "emergency" state. In particular, we analyzed clusters related to salt sensory and signaling, transcription factors, hormone regulation, Reactive Oxygen Species (ROS) scavenging, osmolyte biosynthesis and biomass production, all of them showing different regulation either versus untreated plants or between the two treatments. Importantly, the photosynthesis is strongly impaired in samples treated with both levels of salinity stress. However, in extreme salt conditions, a dramatic switch from C3 Calvin cycle to C4 photosynthesis is likely to occur, this probably being the more impressive finding of our work.

CONCLUSIONS

Considered the distinct response to salt doses, genes either involved in severe or in extreme salt response could constitute useful markers of the physiological status of A. donax to deepen our understanding of its biology and productivity in salinized soil. Finally, many of the unigenes identified in the present study have the potential to be used for the development of A. donax varieties with improved productivity and stress tolerance, in particular the knock out of the GTL1 gene acting as negative regulator of water use efficiency has been proposed as good target for genome editing.

Comprehensive analysis of miRNA profiles reveals the role of Schistosoma japonicum miRNAs at different developmental stages

Schistosomiasis is an important zoonotic disease affecting up to 40 kinds of animals and 250 million people. It has been reported that the miRNAs play a role in the metabolism, differentiation, development and reproduction in many organisms. However, the roles of miRNAs regulating the development, maturation and production in schistosome in both females and males remains unclear. Here we present the dynamic transcriptome analysis of all 79 known Schistosoma japonicum miRNAs from pairing to production, including 14 days post-infection (dpi), 16, 18, 20, 22, 24, 26, 28 dpi female and male, by small RNA sequencing. The miRNA expression profiles showed time-related characteristics in male and female from paring to production, which could be clustered into three patterns, characterized by pairing stage highly expressed (cluster 1), maturating stage highly expressed (cluster 2), and egg producing stage highly expressed (cluster 3). The enrichment of miRNA cluster targeted genes in female and male were distinctly different. Network analysis of miRNAs and their target regulation showed that cluster 1 had 15 miRNAs involved in the regulation of interaction, communication, immune response in female–male and parasite–host. The other 11 miRNAs were involved in gender differentiation and the meiotic cell cycle process. In cluster 2, 11 miRNAs were involved in development and sexual maturation. In cluster 3, 45 miRNAs possibly regulate metabolism and synthesis of the substance for egg production. Analysis of the miRNA regulation network would contribute to understanding the molecular mechanism in S. japonicum development and egg production.

Genome-Wide Identification, Characterization, and Expression Profiling of Glutathione S-Transferase (GST) Family in Pumpkin Reveals Likely Role in Cold-Stress Tolerance

Plant growth and development can be adversely affected by cold stress, limiting productivity. The glutathione S-transferase (GST) family comprises important detoxifying enzymes, which play major roles in biotic and abiotic stress responses by reducing the oxidative damage caused by reactive oxygen species. Pumpkins (Cucurbitamaxima) are widely grown, economically important, and nutritious; however, their yield can be severely affected by cold stress. The identification of putative candidate genes responsible for cold-stress tolerance, including the GST family genes, is therefore vital. For the first time, we identified 32 C. maxima GST (CmaGST) genes using a combination of bioinformatics approaches and characterized them by expression profiling. These CmaGST genes represent seven of the 14 known classes of plant GSTs, with 18 CmaGSTs categorized into the tau class. The CmaGSTs were distributed across 13 of pumpkin's 20 chromosomes, with the highest numbers found on chromosomes 4 and 6. The large number of CmaGST genes resulted from gene duplication; 11 and 5 pairs of CmaGST genes were segmental- and tandem-duplicated, respectively. In addition, all CmaGST genes showed organ-specific expression. The expression of the putative GST genes in pumpkin was examined under cold stress in two lines with contrasting cold tolerance: cold-tolerant CP-1 (C. maxima) and cold-susceptible EP-1 (Cucurbita moschata). Seven genes (CmaGSTU3, CmaGSTU7, CmaGSTU8, CmaGSTU9, CmaGSTU11, CmaGSTU12, and CmaGSTU14) were highly expressed in the cold-tolerant line and are putative candidates for use in breeding cold-tolerant crop varieties. These results increase our understanding of the cold-stress-related functions of the GST family, as well as potentially enhancing pumpkin breeding programs.

Proteomic and biochemical assays of glutathione-related proteins in susceptible and multiple herbicide resistant Avena fatua L

Extensive herbicide usage has led to the evolution of resistant weed populations that cause substantial crop yield losses and increase production costs. The multiple herbicide resistant (MHR) Avena fatua L. populations utilized in this study are resistant to members of all selective herbicide families, across five modes of action, available for A. fatua control in U.S. small grain production, and thus pose significant agronomic and economic threats. Resistance to ALS and ACCase inhibitors is not conferred by target site mutations, indicating that non-target site resistance mechanisms are involved. To investigate the potential involvement of glutathione-related enzymes in the MHR phenotype, we used a combination of proteomic, biochemical, and immunological approaches to compare their constitutive activities in herbicide susceptible (HS1 and HS2) and MHR (MHR3 and MHR4) A. fatua plants. Proteomic analysis identified three tau and one phi glutathione S-transferases (GSTs) present at higher levels in MHR compared to HS plants, while immunoassays revealed elevated levels of lambda, phi, and tau GSTs. GST specific activity towards 1-chloro-2,4-dinitrobenzene was 1.2-fold higher in MHR4 than in HS1 plants and 1.3- and 1.2-fold higher in MHR3 than in HS1 and HS2 plants, respectively. However, GST specific activities towards fenoxaprop-P-ethyl and imazamethabenz-methyl were not different between untreated MHR and HS plants. Dehydroascorbate reductase specific activity was 1.4-fold higher in MHR than HS plants. Pretreatment with the GST inhibitor NBD-Cl did not affect MHR sensitivity to fenoxaprop-P-ethyl application, while the herbicide safener and GST inducer mefenpyr reduced the efficacy of low doses of fenoxaprop-P-ethyl on MHR4 but not MHR3 plants. Mefenpyr treatment also partially reduced the efficacy of thiencarbazone-methyl or mesosulfuron-methyl on MHR3 or MHR4 plants, respectively. Overall, the GSTs described here are not directly involved in enhanced rates of fenoxaprop-P-ethyl or imazamethabenz-methyl metabolism in MHR A. fatua. Instead, we propose that the constitutively elevated GST proteins and related enzymes in MHR plants are representative of a larger, more global suite of abiotic stress-related changes.

Metabolic pathways of benzimidazole anthelmintics in harebell (Campanula rotundifolia)

Benzimidazoles anthelmintics, which enter into environment primarily through excretion in the feces or urine of treated animals, can affect various organisms and disrupt ecosystem balance. The present study was designed to test the phytotoxicity and biotransformation of the three benzimidazole anthelmintics albendazole (ABZ), fenbendazole (FBZ) and flubendazole (FLU) in the harebell (Campanula rotundifolia). This meadow plant commonly grows in pastures and comes into contact with anthelmintics through the excrements of treated animals. Suspensions of harebell cells in culture medium were used as an in vitro model system. ABZ, FLU and FBZ were not found to be toxic for harebell cells, which were able to metabolize ABZ, FLU and FBZ via the formation of a wide scale of metabolites. Ultrahigh-performance liquid chromatography coupled with high mass accuracy tandem mass spectrometry (UHPLC-MS/MS) led to the identification of 24, 18 and 29 metabolites of ABZ, FLU and FBZ, respectively. Several novel metabolites were identified for the first time. Based on the obtained results, the schemes of the metabolic pathways of these anthelmintics were proposed. Most of these metabolites can be considered deactivation products, but a substantial portion of them may readily be decomposed to biologically active substances which could negatively affect ecosystems.

Association between GSTP1 Ile105Val polymorphism and urinary system cancer risk: evidence from 51 studies

The GSTP1 gene plays an important role in detoxification of carcinogens. GSTP1 gene polymorphisms may alter the susceptibility of urinary system cancer. Numerous studies have been performed to investigate the association between GSTP1 Ile105Val (rs1695 A>G) polymorphism and urinary system cancer risk. Nevertheless, the results remain controversial and only prostate cancer and bladder cancer are covered. We identified eligible studies from PubMed, Elsevier, and three equivalent Chinese databases including the Chinese National Knowledge Infrastructure, Wanfang, and Weipu. Pooled odds ratios and 95% confidence intervals were used to assess the strength of the association between GSTP1 Ile105Val polymorphism and urinary system cancer risk. In total, 11,762 cases and 15,150 controls from 51 studies were included in the final meta-analysis. The pooled results from all included studies showed a statistically significant association between GSTP1 Ile105Val polymorphism and urinary system cancer. In the subgroup analyses, the GSTP1 Ile105Val polymorphism was found to be significantly associated with prostate cancer risk and also a risk factor for urinary system cancer among Asians. In conclusion, our meta-analysis indicated that GSTP1 Ile105Val polymorphism was associated with urinary system cancer susceptibility, which needs to be validated by more rigorous data from further large-scale population studies with different ethnicities.

Tobacco plants over-expressing the sweet orange tau glutathione transferases (CsGSTUs) acquire tolerance to the diphenyl ether herbicide fluorodifen and to salt and drought stresses

The glutathione transferases (GSTs) are members of a superfamily of enzymes with pivotal role in the detoxification of both xenobiotic and endogenous compounds. In this work, the generation and characterization of transgenic tobacco plants over-expressing tau glutathione transferases from Citrus sinensis (CsGSTU1 and CsGSTU2) and several cross-mutate forms of these genes are reported. Putative transformed plants were verified for the presence of the transgenes and the relative quantification of transgene copy number was evaluated by Taqman real time PCR. The analysis of gene expression revealed that transformed plants exhibit high levels of CsGSTU transcription suggesting that the insertion of the transgenes occurred in transcriptional active regions of the tobacco genome. In planta studies demonstrate that transformed tobacco plants gain tolerance against fluorodifen. Simultaneously, the wild type CsGSTU genes were in vitro expressed and their kinetic properties were determined using fluorodifen as substrate. The results show that CsGSTU2 follows a Michaelis-Menten hyperbolic kinetic, whereas CsGSTU1 generates a sigmoid plot typical of the regulatory enzymes, thus suggesting that when working at sub-lethal fluorodifen concentrations CsGSTU2 can counteract the herbicide injury more efficiently than the CsGSTU1. Moreover, the transgenic tobacco plant over-expressing CsGSTs exhibited both drought and salinity stress tolerance. However, as we show that CsGSTUs do not function as glutathione peroxidase in vitro, the protective effect against salt and drought stress is not due to a direct scavenging activity of the oxidative stress byproducts. The transgenic tobacco plants, which are described in the present study, can be helpful for phytoremediation of residual xenobiotics in the environment and overall the over-expression of CsGSTUs can be helpful to develop genetically modified crops with high resistance to abiotic stresses.

Italian ryegrass for the phytoremediation of solutions polluted with terbuthylazine

The phytoextraction capacity of Italian ryegrass (Lolium multiflorum L.) to remove terbuthylazine (TBA) from aqueous solution has been assessed using a plant-based biotest (RHIZOtest). Three TBA concentrations (0.5, 1.0 and 2.0 mg L(-1)) were chosen to evaluate the tolerance capacity of the ryegrass. Even though the treatments negatively affected plants, they were able to remove up to 30-40% of TBA. In addition, some enzymatic activities involved in the response to TBA-induced stress were determined. Glutathione S-transferase (GST) has been activated with a TBA-dose dependent trend; ascorbate peroxidase (APX) activities have been induced within the first hours after the treatments, followed by decreases or disappearance in plants exposed to two higher dosages. In conclusion, this case-study highlights that the combination of ryegrass and RHIZOtest resulted to be effective in the remediation of aqueous solutions polluted by TBA.