Molecular cloning, identification of GSTs family in sunflower and their regulatory roles in biotic and abiotic stress

Glutathione S-transferase in mediating adaptive responses of oats (Avena sativa) to osmotic and cadmium stress: genome-wide analysis

BACKGROUND

Glutathione S-transferases (GSTs) are essential multifunctional enzymes. In the face of abiotic stresses such as drought and heavy metal exposure, plants utilize GSTs for detoxification and antioxidant defense, as these enzymes facilitate the conjugation of glutathione (GSH) with toxic compounds. Specific details of this process, however, remain unknown.

RESULTS

This study identified 118 Avena sativa GST (AsGST) genes within the A. sativa genome and classified them into five subfamilies: Tau, Phi, Zeta, Lambda, and EF1Bγ. Phylogenetic analysis revealed that AsGSTs exhibit significant similarity to corresponding GST categories in Arabidopsis thaliana and Oryza sativa, indicating a possible common ancestor. Gene structure and conserved motif analysis demonstrated that AsGST genes within the same subfamily shares similarities in the number and positioning of exons and introns, as well as in motif composition, suggesting that these genes may perform analogous biological functions in A. sativa. The promoter regions of the identified genes are enriched with various cis-acting elements that play roles in plant growth and development, stress response, and hormone signaling. Transcriptomic analysis and real-time quantitative PCR (RT-qPCR) validation indicated that the expression of four AsGST genes (AsGSTU12, AsGSTU13, AsGSTU14, and AsGSTU15) was significantly up-regulated in the roots of A. sativa under both PEG-induced drought stress and CdCl2-induced cadmium stress. These genes likely regulate reactive oxygen species (ROS) levels by catalyzing their scavenging through glutathione (GSH) substrates, and may also participate in ABA signaling and the maintenance of osmotic homeostasis. Under cadmium stress, these genes may mitigate cadmium toxicity by enhancing the chelation and sequestration of cadmium via GSH or through its compartmentalization, as evident from the subcellular localization studies.

CONCLUSION

This study systematically described the GST gene family in A. sativa, characterized its expression patterns and potential functions in response to drought and cadmium stress, and confirmed the essential role of the AsGST gene family in mediating stress responses. The findings enhance our understanding of the mechanisms underlying stress tolerance and offer valuable genetic resources for breeding stress-tolerant A. sativa. The work also provides a theoretical framework and identifies gene targets for the development of stress-resistant A. sativa varieties.

Transgenerational combined toxicity effects of neonicotinoids and triazole pesticides at environmentally relevant concentrations on D. magna: From individual to population level

The transgenerational impacts of pesticide mixture on Daphnia magna (D. magna) following long-term exposure, particularly regarding transcriptomic effects, remain poorly understood. We analyzed 470 irrigation water samples from various Chinese provinces. Imidacloprid (IMI, 71.1 %), clothianidin (CLO, 60.43 %), and tebuconazole (TEB, 64.68 %) were the most frequently detected pesticides, with nearly 50 % of samples showing mixtures of TEB with IMI or CLO. D. magna were exposed to environmentally relevant concentrations (0.89-1.62 μg/L) over 12 generations. Key effects included reduced fecundity, delayed development, and smaller body size, with these impacts exacerbating across generations. A Leslie matrix model revealed declines in population size, intrinsic rates of increase, and age structure. Notably, mixed pesticide exposures induced specific pathways related to oocyte meiosis, resulting in greater toxicity than single exposures. Additionally, disrupted lipid metabolism and feeding behaviors were linked to insufficient energy for growth and reproduction, affecting ovarian development. These findings highlight the ecological risks of long-term pesticide exposure and offer insights for mitigation strategies in aquatic ecosystems.

Genome-Wide Identification and Drought-Responsive Functional Analysis of the GST Gene Family in Potato (Solanum tuberosum L.)

Glutathione S-transferases (GSTs) play crucial roles in crop stress tolerance through protection against oxidative damage. In this study, we conducted genome-wide identification and expression analysis of the GST gene family in the autotetraploid potato cultivar Cooperative-88 (C88) using bioinformatic approaches. We identified 366 GST genes in the potato genome, which were classified into 10 subfamilies. Chromosomal mapping revealed that StGSTs were distributed across all 12 chromosomes, with 13 tandem duplication events observed in three subfamilies. Analysis of protein sequences identified 10 conserved motifs, with motif 1 potentially representing the GST domain. Analysis of cis-acting elements in the StGSTs promoter regions suggested their involvement in stress response pathways. RNA-seq analysis revealed that most StGSTs responded to both drought stress and DNA demethylation treatments. Quantitative PCR validation of 16 selected StGSTs identified four members that showed strong responses to both treatments, with distinct expression patterns between drought-tolerant (QS9) and drought-sensitive (ATL) varieties. Transient expression assays in tobacco demonstrated that these four StGSTs enhanced drought tolerance and may be regulated through DNA methylation pathways, though the precise mechanisms require further investigation. These findings provide a theoretical foundation for understanding the response and epigenetic regulation of potato GST genes under drought stress.

Overlooked and misunderstood: can glutathione conjugates be clues to understanding plant glutathione transferases?

Plant glutathione transferases (GSTs) constitute a large and diverse family of enzymes that are involved in plant stress response, metabolism and defence, yet their physiological functions remain largely elusive. Consistent with the traditional view on GSTs across organisms as detoxification enzymes, in vitro most plant GSTs catalyse glutathionylation, conjugation of the tripeptide glutathione (GSH; γ-Glu-Cys-Gly) onto reactive molecules. However, when it comes to elucidating GST functions, it remains a key challenge that the endogenous plant glutathione conjugates (GS-conjugates) that would result from such glutathionylation reactions are rarely reported. Furthermore, GSTs often display high substrate promiscuity, and their proposed substrates are prone to spontaneous chemical reactions with GSH; hence, single-gene knockouts rarely provide clear chemotypes or phenotypes. In a few cases, GS-conjugates are demonstrated to be biosynthetic intermediates that are rapidly further metabolized towards a pathway end product, explaining their low abundance and rare detection. In this review, we summarize the current knowledge of plant GST functions and how and possibly why evolution has resulted in a broad and extensive expansion of the plant GST family. Finally, we demonstrate that endogenous GS-conjugates are more prevalent in plants than assumed and suggest they are overlooked as clues towards the identification of plant GST functions. This article is part of the theme issue 'The evolution of plant metabolism'.

Using Transcriptomics to Determine the Mechanism for the Resistance to Fusarium Head Blight of a Wheat-Th. elongatum Translocation Line

Fusarium head blight (FHB), caused by the Fusarium graminearum species complex, is a destructive disease in wheat worldwide. The lack of FHB-resistant germplasm is a barrier in wheat breeding for resistance to FHB. Thinopyrum elongatum is an important relative that has been successfully used for the genetic improvement of wheat. In this study, a translocation line, YNM158, with the YM158 genetic background carrying a fragment of diploid Th. elongatum 7EL chromosome created using 60Co-γ radiation, showed high resistance to FHB under both field and greenhouse conditions. Transcriptome analysis confirmed that the horizontal transfer gene, encoding glutathione S-transferase (GST), is an important contributor to FHB resistance in the pathogen infection stage, whereas the 7EL chromosome fragment carries other genes regulated by F. graminearum during the colonization stage. Introgression of the 7EL fragment affected the expression of wheat genes that were enriched in resistance pathways, including the phosphatidylinositol signaling system, protein processing in the endoplasmic reticulum, plant-pathogen interaction, and the mitogen-activated protein kinase (MAPK) signaling pathway at different stages after F. graminearium infection. This study provides a novel germplasm for wheat resistance to FHB and new insights into the molecular mechanisms of wheat resistance to FHB.

Hydrogen sulfide priming enhanced salinity tolerance in sunflower by modulating ion hemostasis, cellular redox balance, and gene expression

BACKGROUND

The salinity threat represents an environmental challenge that drastically affects plant growth and yield. Besides salinity stress, the escalating world population will greatly influence the world's food security in the future. Therefore, searching for effective strategies to improve crop salinity resilience and sustain agricultural productivity under high salinity is a must. Seed priming is a reliable, simple, low-risk, and low-cost technique. Therefore, this work aimed to evaluate the impact of seed priming with 0.5 mM NaHS, as a donor of H2S, in mitigating salinity effects on sunflower seedlings. Primed and nonprime seeds were established in nonsaline soil irrigated with tape water for 14 d, and then exposed to 150 mM NaCl for 7 d.

RESULTS

Salinity stress significantly reduced the seedling growth, biomass accumulation, K+, Ca2+, and salinity tolerance index while elevating Na+ uptake and translocation. Salinity-induced adverse effects were significantly alleviated by H2S priming. Upregulation in gene expression (HaSOS2, HaGST) under NaCl stress was further enhanced by H2S priming. Also, H2S reduced lipid peroxidation, electrolyte leakage, and H2O2 content, but elevated the antioxidant defense system. NaCl-induced levels of ascorbate, glutathione, and α tocopherol, as well as the activities of AsA-GSH cycle enzymes: ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and glutathione S-transferase, were further enhanced by H2S priming. Increased level of H2S and total thiol by NaCl was also further stimulated by H2S priming.

CONCLUSION

H2S priming has proved to be an efficient strategy to improve sunflower seedlings' salinity tolerance by retaining ion homeostasis, detoxifying oxidative damage, modulating gene expression involved in ion homeostasis and ROS scavenging, and boosting endogenous H2S. These findings suggested that H2S acts as a regulatory molecule activating the functional processes responsible for sunflower adaptive mechanisms and could be adopted as a crucial crop management strategy to combat saline conditions. However, it would be of great interest to conduct further studies in the natural saline field to broaden our understanding of crop adaptive mechanisms and to support our claims.

Acute toxicity, oxidative stress, and apoptosis due to short-term triclosan exposure and multi- and transgenerational effects on in vivo endpoints, antioxidant defense, and DNA damage response in the freshwater water flea Daphnia magna

In this study, we measured the acute toxicity of triclosan (TCS) in neonate and adult Daphnia magna water fleas. The median lethal concentrations were 184.689 and 349.511 μg/L, respectively. Oxidative stress induced by TCS was analyzed based on changes in reactive oxygen species (ROS) content and antioxidant enzymatic activities in D. magna. Based on these endpoints, TCS concentrations of 50 and 100 μg/L induced oxidative stress. However, several apoptosis-mediated proteins showed TCS-induced oxidative-stress damage in response to 25 μg/L, indicating that apoptotic proteins were the most sensitive mediators. We also evaluated the multi- and transgenerational effects of TCS on D. magna over three generations in terms of various in vivo endpoints, DNA damage responses, and biochemical reactions. The transgenerational group exposed to TCS exhibited greater negative impacts on antioxidant responses, DNA fragmentation status, and biological endpoints compared with the multigenerational exposure group, leading to decreased reproductive rates and higher ROS content. The transcriptional expression levels of glutathione S-transferase genes in the transgenerational exposure group were upregulated compared to those in the multigenerational group but were fully recovered in F2 offspring. Our findings provide an in-depth understanding of the adaptive effects of multigenerational exposure to TCS.

Genome-Wide Identification and Expression Profiling of Glutathione S-Transferase Gene Family in Foxtail Millet (Setaria italica L.)

Glutathione S-transferases (GSTs) are a critical superfamily of multifunctional enzymes in plants. As a ligand or binding protein, GSTs regulate plant growth and development and detoxification. Foxtail millet (Setaria italica (L.) P. Beauv) could respond to abiotic stresses through a highly complex multi-gene regulatory network in which the GST family is also involved. However, GST genes have been scarcely studied in foxtail millet. Genome-wide identification and expression characteristics analysis of the foxtail millet GST gene family were conducted by biological information technology. The results showed that 73 GST genes (SiGSTs) were identified in the foxtail millet genome and were divided into seven classes. The chromosome localization results showed uneven distribution of GSTs on the seven chromosomes. There were 30 tandem duplication gene pairs belonging to 11 clusters. Only one pair of SiGSTU1 and SiGSTU23 were identified as fragment duplication genes. A total of ten conserved motifs were identified in the GST family of foxtail millet. The gene structure of SiGSTs is relatively conservative, but the number and length of exons of each gene are still different. The cis-acting elements in the promoter region of 73 SiGST genes showed that 94.5% of SiGST genes possessed defense and stress-responsive elements. The expression profiles of 37 SiGST genes covering 21 tissues suggested that most SiGST genes were expressed in multiple organs and were highly expressed in roots and leaves. By qPCR analysis, we found that 21 SiGST genes were responsive to abiotic stresses and abscisic acid (ABA). Taken together, this study provides a theoretical basis for identifying foxtail millet GST family information and improving their responses to different stresses.

Glutathione S-transferase interactions enhance wheat resistance to powdery mildew but not wheat stripe rust

Wheat stripe rust and powdery mildew are important worldwide diseases of wheat (Triticum aestivum). The wheat cultivar Xingmin318 (XM318) is resistant to both wheat stripe rust and powdery mildew, which are caused by Puccinia striiformis f. sp. tritici (Pst) and Blumeria graminis f. sp. tritici (Bgt), respectively. To explore the difference between wheat defense response against Pst and Bgt, quantitative proteomic analyses of XM318 inoculated with either Pst or Bgt were performed using tandem mass tags technology. A total of 741 proteins were identified as differentially accumulated proteins (DAPs). Bioinformatics analyses indicated that some functional categories, including antioxidant activity and immune system process, exhibited obvious differences between Pst and Bgt infections. Intriguingly, only 42 DAPs responded to both Pst and Bgt infections. Twelve DAPs were randomly selected for reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis, and the mRNA expression levels of 11 were consistent with their protein expression. Furthermore, gene silencing using the virus-induced gene silencing system indicated that glutathione S-transferase (TaGSTU6) has an important role in resistance to Bgt but not to Pst. TaGSTU6 interacted with the cystathionine beta-synthase (CBS) domain-containing protein (TaCBSX3) in both Pst and Bgt infections. Knockdown of TaCBSX3 expression only reduced wheat resistance to Bgt infection. Overexpression of TaGSTU6 and TaCBSX3 in Arabidopsis (Arabidopsis thaliana) promoted plant resistance to Pseudomonas syringae pv. Tomato DC3000. Our results indicate that TaGSTU6 interaction with TaCBSX3 only confers wheat resistance to Bgt, suggesting that wheat has different response mechanisms to Pst and Bgt stress.

Fine-mapping of a putative glutathione S-transferase (GST) gene responsible for yellow seed colour in flax (Linum usitatissimum)

Objective

The brown seed coat colour of flax (Linum ustiatissimum) results from proanthocyanidin synthesis and accumulation. Glutathione S-transferases (GSTs), such as the TT19 protein in Arabidopsis, have been implicated in the transport of anthocyanidins during the synthesis of the brown proanthocyanidins. This study fine mapped the g allele responsible for yellow seed colour in S95407 and identified it as a putative mutated GST.

Results

We developed a Recombinant Inbred Line population with 320 lines descended from a cross between CDC Bethune (brown seed coat) and S95407 (yellow seed) and used molecular markers to fine map the G gene on Chromosome 6 (Chr 6). We used Next Generation Sequencing (NGS) to identify a putative GST was identified in this region and Sanger sequenced the gene from CDC Bethune, S95407 and other yellow seeded genotypes. The putative GST from S95407 had 13 SNPs encoding, including four non-synonymous amino acid changes, compared to the CDC Bethune reference sequence and the other genotypes. The GST encoded by Lus10019895 is a lambda-GST in contrast to the Arabidopsis TT19 which is a phi-GST.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-05964-x.

Natural occurrence of mesta yellow vein mosaic virus and DNA-satellites in ornamental sunflower (Helianthus spp.) in Pakistan

Weeds and ornamental plants serve as a reservoir for geminiviruses and contribute to their dissemination, genome recombination and/or satellite capture. Ornamental sunflower (Helianthus spp.) plants exhibiting mild leaf curl symptoms were subjected to begomovirus and DNA-satellites isolation. The full-length genome of the isolated begomovirus clone (Od1-A) showed 96.8% nucleotide (nt) sequence identity with mesta yellow vein mosaic virus (MeYVMV; accession no. FR772081) whereas, alphasatellite (Od1-a) and betasatellite (Od1-b) clones showed their highest nt sequence identities at 97.4% and 98.2% with ageratum enation alphasatellite (AEA; accession no. FR772085) and papaya leaf curl betasatellite (PaLCuB; accession. no. LN878112), respectively. The evolutionary relationships, average evolutionary divergence and the recombination events were also inferred. The MeYVMV exhibited 9.5% average evolutionary divergence and its CP and Rep had 9.3% and 12.2%, concomitantly; the alphasatellite and the betasatellite had 8.3% and 5.2%, respectively. The nt substitution rates (site^-1 year⁻¹) were found to be 6.983 × 10^-04 and 5.702 × 10^-05 in the CP and Rep of MeYVMV, respectively. The dN/dS ratio and the Tajima D value of MeYVMV CP demonstrated its possible role in host switching. The absolute quantification of the begomovirus demonstrated that mild symptoms might have a correlation with low virus titer. This is the first identification of MeYVMV and associated DNA-satellites from ornamental sunflower in Pakistan. The role of sequence divergence, recombination and importance of MeYVMV along with DNA-satellites in extending its host range is discussed.

Identification of glutathione transferase gene associated with partial resistance to Sclerotinia stem rot of soybean using genome-wide association and linkage mapping

KEY MESSAGE

Association and linkage mapping techniques were used to identify and verify single nucleotide polymorphisms (SNPs) associated with Sclerotinia sclerotiorum resistance. A novel resistant gene, GmGST , was cloned and shown to be involved in soybean resistance to SSR. Sclerotinia stem rot (SSR), caused by the fungus Sclerotinia sclerotiorum, is one of the most devastating diseases in soybean (Glycine max (Linn.) Merr.) However, the genetic architecture underlying soybean resistance to SSR is poorly understood, despite several mapping and gene mining studies. In the present study, the identification of quantitative trait loci (QTLs) involved in the resistance to S. sclerotiorum was conducted in two segregating populations: an association population that consisted of 261 diverse soybean germplasms, and the MH population, derived from a cross between a partially resistant cultivar (Maple arrow) and a susceptible cultivar (Hefeng25). Three and five genomic regions affecting resistance were detected by genome-wide association study to control the lesion length of stems (LLS) and the death rate of seedling (DRS), respectively. Four QTLs were detected to underlie LLS, and one QTL controlled DRS after SSR infection. A major locus on chromosome (Chr.) 13 (qDRS13-1), which affected both DRS and LLS, was detected in both the natural population and the MH population. GmGST, encoding a glutathione S-transferase, was cloned as a candidate gene in qDRS13-1. GmGST was upregulated by the induction of the partially resistant cultivar Maple arrow. Transgenic experiments showed that the overexpression of GmGST in soybean increased resistance to S. sclerotiorum and the content of soluble pigment in stems of soybean. The results increase our understanding of the genetic architecture of soybean resistance to SSR and provide a framework for the future marker-assisted breeding of resistant soybean cultivars.

Quaternary ammonium iminofullerenes promote root growth and osmotic-stress tolerance in maize via ROS neutralization and improved energy status

In the present study, the role of quaternary ammonium iminofullerenes (IFQA) on the root growth of plant seedlings was investigated. The root elongation of Arabidopsis and maize exposed to 20 and 50 mg/L of IFQA was promoted under normal and osmotic stress conditions, respectively. In the meantime, the root active absorption area and adenosine triphosphate content in roots of maize seedlings were enhanced by IFQA treatment, however, the contents of hydrogen peroxide (H₂O₂) and malondialdehyde in roots were down-regulated. IFQA application improved glutathione transferase and glutathione reductase activities and the ratios of glutathione/oxidized glutathione and ascorbic acid/dehydroascorbic acid, and restored the inhibition of root elongation caused by the excess accumulation of H₂O₂ in roots of maize seedlings under osmotic stress. Furthermore, the expression of 14 proteins involved in cell growth, energy metabolism, and stress response in maize roots was upregulated by two-dimensional electrophoresis combined with mass spectrometry. This analysis revealed that IFQA stimulated the redox pathway to maintain balance levels of reactive oxygen species to ensure normal cell metabolism, promote energy production for root growth, and enhance osmotic-stress tolerance. It provided crucial information to elucidate the mechanism of the root growth of crop seedlings enhanced by water-soluble fullerene-based nanomaterials.

Genome-wide identification, characterization, and expression analysis related to autotoxicity of the GST gene family in Cucumis melo L

Glutathione S-transferase (GST) plays an important role in plant resistance to biotic and abiotic stresses. In this paper, the characteristics of melon GST gene family members were analyzed from a genome-wide perspective. Forty-nine GSTs were identified in melon genome, belonging to eight classes. Through the phylogenetic analysis of GST proteins in melon and other plants, it was found that members from the same subfamily in different species clustered together, indicating that the subfamilies of GST have diversified before the divergence within these species. The results of chromosome mapping showed that GSTs were present in all chromosomes except for chromosome 5. Gene replication events played an important role in the expansion and evolution of melon GST gene family. Ten GSTs with significant differential expression were screened in the transcriptome database related to melon autotoxicity stress. The differential expression of these 10 GSTs was detected in roots and leaves of melon seedlings treated with cinnamic acid. The relative expression level of CmGSTU7, CmGSTU10, CmGSTU18, CmGSTF2 and CmGSTL1 in roots of melon seedlings was significantly higher than that in control group. It suggested that the five GSTs might play an important role in cinnamic acid mediated autotoxicity stress in melon. The results of this paper were helpful to reveal the evolution and functional succession of GST family and further understand the response of GST to autotoxicity stress in melon.

Association of Genetic Polymorphisms in GSTP1, GSTM1, and GSTT1 Genes with Vesicoureteral Reflux Susceptibility in the Children of Southeast Iran

Background:

Vesicoureteral reflux (VUR) disease is the most common type of urinary tract anomalies in children. Genetic risk factors may be associated with the etiology of VUR. The role of the Glutathione S-transferases (GSTs) as multifunctional enzymes is cellular oxidative stress handling. This is the first study aimed at evaluating the relative risk of GSTP1, GSTM1, and GSTT1 polymorphisms in VUR susceptibility in children and provides new important insights into the genetics of affected children.

Methods:

The study was done in 2013 in Sistan and Baluchestan University, eastern Iran. Genotyping of three GSTP1, GSTM1, and GSTT1 genes were determined using the multiplex polymerase chain reaction assay in 216 reactions for 72 VUR children and 312 reactions for 104 healthy controls.

Results:

The presence of GSTT1 deletion was associated with high risk of VUR in children, whereas GSTP1 and GSTM1 genotypes did not show the same effect. Furthermore, the combination of GSTT1/GSTM1 and GSTT1/ GSTP1 genotypes showed a significant influence on lower risk of VUR in children.

Conclusion:

Deletion of GSTT1 functional gene is a genetic risk factor causing VUR in children. Interestingly, the combination of GSTM1 and GSTP1 null genotypes with GSTT1 has shown a protective role against risk of GSTT1 deletion.

Genome-wide identification of glutathione S-transferase gene family in pepper, its classification, and expression profiling under different anatomical and environmental conditions

Glutathione S-transferases (GSTs) compose a family of multifunctional enzymes involved in the numerous aspects of regulating plant growth, development, and stress response. An in silico genome-wide analysis of pepper (Capsicum annuum L.) was performed to identify eighty-five GST genes that were annotated according to their chromosomal location. Segmental duplication contributed more than tandem duplication for the expansion of GST gene family in pepper. All the identified members belong to ten different classes which are highly conserved among Arabidopsis, rice, tomato and potato counterparts indicating the pre-dicot-monocot split diversification of GST classes. Gene structure, protein domain, and motif organization were found to be notably conserved over the distinct phylogenetic groups, which demonstrated the evolutionary significant role of each class. Expression of most of the CaGST transcripts as well as the total pepper GST activity was found to be significantly up-regulated in response to cold, heat, drought, salinity and osmotic stress conditions. Presence of various hormone and stress-responsive cis-elements on most of the putative CaGST promoter regions could be directly correlated with the alteration of their transcripts. All these findings might provide opportunities for future functional validation of this important gene family in pepper.