Stress Tolerance Mechanisms Research Articles

Characterization of the basic leucine zipper transcription factor family of Neoporphyra haitanensis and its role in acclimation to dehydration stress

BackgroundNeoporphyra haitanensis, a major marine crop native to southern China, grows in the harsh intertidal habitats of rocky coasts. The thallus can tolerate fluctuating and extreme environmental stresses, for example, repeated desiccation/rehydration due to the turning tides. It is also a typical model system for investigating stress tolerance mechanisms in intertidal seaweed. The basic leucine zipper (bZIP) transcription factors play important roles in the regulation of plants’ responses to environmental stress stimuli. However, little information is available regarding the bZIP family in the marine crop Nh. haitanensis.ResultsWe identified 19 bZIP genes in the Nh. haitanensis genome and described their conserved domains. Based on phylogenetic analysis, these 19 NhhbZIP genes, distributed unevenly on the 11 superscaffolds, were divided into four groups. In each group, there were analogous exon/intron numbers and motif compositions, along with diverse exon lengths. Cross-species collinearity analysis indicated that 17 and 9 NhhbZIP genes were orthologous to bZIP genes in Neopyropia yezoensis and Porphyra umbilicalis, respectively. Evidence from RNA sequencing (RNA-seq) data showed that the majority of NhhbZIP genes (73.68%) exhibited transcript abundance in all treatments. Furthermore, genes NN 2, 4 and 5 showed significantly altered expression in response to moderate dehydration, severe dehydration, and rehydration, respectively. Gene co-expression network analysis of the representative genes was carried out, followed by gene set enrichment analysis. Two NhhbZIP genes collectively responding to dehydration and rehydration and their co-expressing genes mainly participated in DNA repair, DNA metabolic process, and regulation of helicase activity. Two specific NhhbZIP genes responding to severe dehydration and their corresponding network genes were mainly involved in macromolecule modification, cellular catabolic process, and transmembrane transport. Three specific NhhbZIP genes responding to rehydration and their co-expression gene networks were mainly involved in the regulation of the cell cycle process and defense response.ConclusionsThis study provides new insights into the structural composition, evolution, and function of the NhhbZIP gene family. Our results will help us to further study the functions of bZIP genes in response to dehydration and rehydration in Nh. haitanensis and improve Nh. haitanensis in southern China.

Genome-Wide Identification and Comprehensive Analysis of the GASA Gene Family in Peanuts (Arachis hypogaea L.) under Abiotic Stress

Peanut (Arachis hypogaea L.) is a globally cultivated crop of significant economic and nutritional importance. The role of gibberellic-acid-stimulated Arabidopsis (GASA) family genes is well established in plant growth, development, and biotic and abiotic stress responses. However, there is a gap in understanding the function of GASA proteins in cultivated peanuts, particularly in response to abiotic stresses such as drought and salinity. Thus, we conducted comprehensive in silico analyses to identify and verify the existence of 40 GASA genes (termed AhGASA) in cultivated peanuts. Subsequently, we conducted biological experiments and performed expression analyses of selected AhGASA genes to elucidate their potential regulatory roles in response to drought and salinity. Phylogenetic analysis revealed that AhGASA genes could be categorized into four distinct subfamilies. Under normal growth conditions, selected AhGASA genes exhibited varying expressions in young peanut seedling leaves, stems, and roots tissues. Notably, our findings indicate that certain AhGASA genes were downregulated under drought stress but upregulated under salt stress. These results suggest that specific AhGASA genes are involved in the regulation of salt or drought stress. Further functional characterization of the upregulated genes under both drought and salt stress will be essential to confirm their regulatory roles in this context. Overall, our findings provide compelling evidence of the involvement of AhGASA genes in the mechanisms of stress tolerance in cultivated peanuts. This study enhances our understanding of the functions of AhGASA genes in response to abiotic stress and lays the groundwork for future investigations into the molecular characterization of AhGASA genes.

Toxicity of mercuric oxide nanoparticles on freshwater microalgae: Comprehensive analysis on their interactive effects and detoxification pathways

So far, there is limited research on the potential risks and environmental consequences of mercuric oxide nanoparticles (HgO-NPs) on phytoplankton. To this end, we investigated the moderate and acute concentrations of HgO-NPs (0.8 and 1.6 mg/L, respectively) on the growth, photosynthesis, and detoxification processes in two microalgae, namely Scenedesmus obliquus and Nostoc muscorum. Compared to N. muscorum, S. obliquus had greater accumulation and removal efficiencies of HgO-NPs (92.8 %, 91.4 %) at moderate and acute levels. HgO-NPs accumulation inhibited the growth and decreased photosynthesis, RuBisCo activity and chlorophyll a content in a dose-dependent manner. At oxidative damage level, acute level of HgO-NPs evoked severe lipid and protein peroxidation, and increased NADPH oxidase activity particularly in N. muscorum. Exposure to HgO-NPs also resulted in distinct metabolic perturbations in both microalgal species. Notably, there was a dose-dependent increase in the activity of antioxidant enzymes (e.g., peroxidase and superoxide dismutase), as well as metabolites like tocopherols and flavonoids in S. obliquus. However, the activity of catalase, ascorbate peroxidase and dehydroascorbate reductase enzymes, and ascorbate levels were significantly increased in N. muscorum. At HgO-NPs detoxification level, S. obliquus increased glutathione level and glutathione-S-transferases activity. However, N. muscorum showed high levels of metal chelator (phytochelatins and metalothionine). Investigating the HgO-NPs bioremediation capacity and stress tolerance mechanisms opens possibilities to introduce S. obliquus as a promising bioremediator to relieve ecological risk of HgO-NPs.

Identification, characterization and expression analysis of wheat RSH family genes under abiotic stress

Guanosine pentaphosphate and guanosine tetraphosphate are collectively called (p)ppGpp (Guanosine tetraphosphate and pentaphosphate). (p)ppGpp content in plants is affected by conditions such as light, salt, pH, UV light, and environmental phytohormones. The synthesis and hydrolysis of (p)ppGpp in plants is accomplished by a class of proteins called RSH (RelA/SpoT homologs). To date, a systematic and comprehensive genome-wide analysis of the RSH gene family in wheat and its closely related species has not been conducted. In this study, 15, 14, 12, and 8 members of RSH were identified in wheat (Triticum aestivum), Triticum dicoccoides, Triticum urartu and Aegilops tauschii respectively. Based on the conserved structural domains of the RSH genes, the TaRSHs have been categorized into TaRSH and TaCRSH. The gene duplications in the TaRSH gene family were all identified as segmental duplications indicating that the TaRSH family plays a significant role in expansion and that segmental duplications maintain a degree of genetic stability. Through the analysis of transcriptome data and RT-qPCR experiments, it was observed that the expression levels of TaRSHs were upregulated in response to abiotic stress. This upregulation suggests that TaRSHs play a crucial role in enhancing the resilience of wheat to adverse environmental conditions during its growth and development. Their increased expression likely contributes to the acquisition of stress tolerance mechanisms in wheat. Especially under NaCl stress, the expression levels increased most significantly. The more detailed systematic analysis provided in this article will help us understand the role of TaRSHs and provide a reference for further research on its molecular biological functions in wheat.

Endophyte Inoculation Enhances Growth, Secondary Metabolites and Biological Activity of Endostemon obtusifolius Grown Under Drought Stress

There is a need to cultivate medicinal plants to meet the growing demand. Their cultivation is hampered by extreme environmental conditions such as drought that affect plant growth and its pharmacological potential. Application of stress-tolerant endophytic species may potentially attenuate these negative impacts. This study assessed the effects of individual and co-inoculation of two native endophytic species (bacterium Paenibacillus polymyxa and fungus Fusarium oxysporum) on growth, physiological responses, metabolite accumulation and therapeutic efficacy of Endostemon obtusifolius subjected to varying watering regimes (well watered, mild and severe stress) under greenhouse conditions. Drought stress negatively affected root and shoot biomass, carotenoid content, chlorophyll fluorescence and relative water content in E. obtusifolius. Electrolyte leakage and malondialdehyde and hydrogen peroxide accumulation increased with drought stress. Individual and co-inoculation endophyte treatments significantly improved growth and stress tolerance mechanisms via increased osmolyte production (soluble sugars, proline), up-regulation of the enzymatic antioxidant system (superoxide dismutase) and increased antioxidant metabolite content (total phenolics, flavonoids). Antioxidant (DPPH, FRAP) and in vitro α-glucosidase activity of ethyl acetate leaf extracts were negatively affected by water stress but significantly improved when plantlets were subjected to endophyte inoculation. The most active extracts were from plants subjected to mild water stress with co-inoculation. Thus severe drought stress negatively affected growth and therapeutic efficacy of E. obtusifolius. Inoculation with beneficial endophytes enhanced the biochemical responses, osmoregulatory network and improved the therapeutic efficacy of E. obtusifolius.

Taxonomic identification and temperature stress tolerance mechanisms of Aequorivita marisscotiae sp. nov

The deep sea harbours microorganisms with unique life characteristics and activities due to adaptation to particular environmental conditions, but the limited sample collection and pure culture techniques available constrain the study of deep-sea microorganisms. In this study, strain Ant34-E75 was isolated from Antarctic deep-sea sediment samples and showed the highest 16 S rRNA gene sequence similarity (97.18%) with the strain Aequorivita viscosa 8-1bT. Strain Ant34-E75 is psychrotrophic and can effectively increase the cold tolerance of Chlamydomonas reinhardtii (a model organism). Subsequent transcriptome analysis revealed multiple mechanisms involved in the Ant34-E75 response to temperature stress, and weighted gene co-expression network analysis (WGCNA) showed that the peptidoglycan synthesis pathway was the key component. Overall, this study provides insights into the characteristics of a deep-sea microorganism and elucidates mechanisms of temperature adaptation at the molecular level.

Genome sequencing of Syzygium cumini (jamun) reveals adaptive evolution in secondary metabolism pathways associated with its medicinal properties.

Syzygium cumini, also known as jambolan or jamun, is an evergreen tree widely known for its medicinal properties, fruits, and ornamental value. To understand the genomic and evolutionary basis of its medicinal properties, we sequenced S. cumini genome for the first time from the world's largest tree genus Syzygium using Oxford Nanopore and 10x Genomics sequencing technologies. We also sequenced and assembled the transcriptome of S. cumini in this study. The tetraploid and highly heterozygous draft genome of S. cumini had a total size of 709.9 Mbp with 61,195 coding genes. The phylogenetic position of S. cumini was established using a comprehensive genome-wide analysis including species from 18 Eudicot plant orders. The existence of neopolyploidy in S. cumini was evident from the higher number of coding genes and expanded gene families resulting from gene duplication events compared to the other two sequenced species from this genus. Comparative evolutionary analyses showed the adaptive evolution of genes involved in the phenylpropanoid-flavonoid (PF) biosynthesis pathway and other secondary metabolites biosynthesis such as terpenoid and alkaloid in S. cumini, along with genes involved in stress tolerance mechanisms, which was also supported by leaf transcriptome data generated in this study. The adaptive evolution of secondary metabolism pathways is associated with the wide range of pharmacological properties, specifically the anti-diabetic property, of this species conferred by the bioactive compounds that act as nutraceutical agents in modern medicine.

Identifying biomass yield potential of tetra‐, hexa‐, and octoploid prairie cordgrass populations grown on marginal lands

AbstractAs the demand for renewable energy sources with reduced carbon emissions to the atmosphere increases, bioenergy crops remain an attractive alternative to fossil fuels. Another appeal of bioenergy crops is the potential utilization of marginal lands not suitable for food crops. Prairie cordgrass is a perennial warm‐season polyploid grass species that is considered a bioenergy crop that also exhibits a high tolerance for salinity and flooding. The ploidy level of prairie cordgrass has previously been suggested to correlate with agronomic traits. However, little is known about the agricultural performance of prairie cordgrass on marginal lands and if a correlation of ploidy level and stress tolerance exists. In this experiment, the productivity of tetra‐, hexa‐, and octoploids was investigated when grown on three different marginal sites, including waterlogged, saline, and low‐nutrient gravelly soils. Here, we found that prairie cordgrass populations annually produced dry biomass on a wet marginal site comparable to normal cropland. However, the productivity was remarkedly decreased at both a salt‐affected site and a limestone mine reclamation site. We were unable to conclude that different ploidy levels affected the biomass yield of prairie cordgrass grown under abiotic stress. However, there was a differential response of populations to various types of marginal sites. These results indicate potential genetic resources for developing breeding targets and identifying mechanisms of abiotic stress tolerance. Moreover, we highlight the need to generate diverse ploidy levels of prairie cordgrass in the same genetic backgrounds for future testing.

Drought stress tolerance in rice: a critical insight

Drought is currently a serious threat for farming especially in rice cultivation, due to its substantial water requirements throughout its lifecycle. Drought is one of the major environmental constraints disrupting the growth and yield of rice plants, affecting them at physiological, morphological, biochemical and molecular levels. Global climate change exacerbates this issue, leading to substantial economic losses. As rice is a major food crop worldwide, the demand for rice production is increasing in tandem with the expanding human population. Consequently, it has become imperative to utilize drought-prone areas for agriculture and develop drought-tolerant rice genotypes. In addition to conventional breeding methods, the application of multi-omics approaches proves most effective in meeting the need to enhance drought tolerance in rice plants. Protective mechanisms, such as morphological adaptation, physiological acclimatization, cellular adjustments and antioxidant defense, play pivotal roles in helping plants overcome drought stress. Plant-microbial interactions are important for plants to overcome drought-induced adversities. Furthermore, applications of conventional approaches, omics approaches and nanotechnology are very promising for generating climate smart agriculture. Our aim in this review is to focus on drought stress tolerance in rice including drought-tolerant rice genotypes, their adaptation mechanisms, the unveiling the genes, transcription factors, microRNAs (miRNA) involved, microbial assistance and exploring approaches to mitigate drought stress in rice plants. The present review might throw some light on understanding the mechanism of drought stress tolerance in rice, including its molecular crosstalk and biochemical dynamics, for future researchers.

Telomere-to-telomere genome of the allotetraploid legume Sesbania cannabina reveals transposon-driven subgenome divergence and mechanisms of alkaline stress tolerance.

Alkaline soils pose an increasing problem for agriculture worldwide, but using stress-tolerant plants as green manure can improve marginal land. Here, we show that the legume Sesbania cannabina is very tolerant to alkaline conditions and, when used as a green manure, substantially improves alkaline soil. To understand genome evolution and the mechanisms of stress tolerance in this allotetraploid legume, we generated the first telomere-to-telomere genome assembly of S. cannabina spanning ∼2,087 Mb. The assembly included all centromeric regions, which contain centromeric satellite repeats, and complete chromosome ends with telomeric characteristics. Further genome analysis distinguished A and B subgenomes, which diverged approximately 7.9 million years ago. Comparative genomic analysis revealed that the chromosome homoeologs underwent large-scale inversion events (>10 Mb) and a significant, transposon-driven size expansion of the chromosome 5A homoeolog. We further identified four specific alkali-induced phosphate transporter genes in S. cannabina; these may function in alkali tolerance by relieving the deficiency in available phosphorus in alkaline soil. Our work highlights the significance of S. cannabina as a green tool to improve marginal lands and sheds light on subgenome evolution and adaptation to alkaline soils.

Novel insights into the mechanism(s) of silicon-induced drought stress tolerance in lentil plants revealed by RNA sequencing analysis

BackgroundLentil is an essential cool-season food legume that offers several benefits in human nutrition and cropping systems. Drought stress is the major environmental constraint affecting lentil plants’ growth and productivity by altering various morphological, physiological, and biochemical traits. Our previous research provided physiological and biochemical evidence showing the role of silicon (Si) in alleviating drought stress in lentil plants, while the molecular mechanisms are still unidentified. Understanding the molecular mechanisms of Si-mediated drought stress tolerance can provide fundamental information to enhance our knowledge of essential gene functions and pathways modulated by Si during drought stress in plants. Thus, the present study compared the transcriptomic characteristics of two lentil genotypes (drought tolerant-ILL6002; drought sensitive-ILL7537) under drought stress and investigated the gene expression in response to Si supplementation using high-throughput RNA sequencing.ResultsThis study identified 7164 and 5576 differentially expressed genes (DEGs) from drought-stressed lentil genotypes (ILL 6002 and ILL 7537, respectively), with Si treatment. RNA sequencing results showed that Si supplementation could alter the expression of genes related to photosynthesis, osmoprotection, antioxidant systems and signal transduction in both genotypes under drought stress. Furthermore, these DEGs from both genotypes were found to be associated with the metabolism of carbohydrates, lipids and proteins. The identified DEGs were also linked to cell wall biosynthesis and vasculature development. Results suggested that Si modulated the dynamics of biosynthesis of alkaloids and flavonoids and their metabolism in drought-stressed lentil genotypes. Drought-recovery-related DEGs identified from both genotypes validated the role of Si as a drought stress alleviator. This study identified different possible defense-related responses mediated by Si in response to drought stress in lentil plants including cellular redox homeostasis by reactive oxygen species (ROS), cell wall reinforcement by the deposition of cellulose, lignin, xyloglucan, chitin and xylan, secondary metabolites production, osmotic adjustment and stomatal closure.ConclusionOverall, the results suggested that a coordinated interplay between various metabolic pathways is required for Si to induce drought tolerance. This study identified potential genes and different defence mechanisms involved in Si-induced drought stress tolerance in lentil plants. Si supplementation altered various metabolic functions like photosynthesis, antioxidant defence system, osmotic balance, hormonal biosynthesis, signalling, amino acid biosynthesis and metabolism of carbohydrates and lipids under drought stress. These novel findings validated the role of Si in drought stress mitigation and have also provided an opportunity to enhance our understanding at the genomic level of Si’s role in alleviating drought stress in plants.

Understanding of effect and mechanism of abiotic stress tolerance in legumes and recent development

The present changing climatic conditions are affecting crop productivity worldwide. The crop growth and productivity are adversely hit by perturbed climatic conditions and climate change. Being sessile, plants are openly exposed to biotic and abiotic stresses which limit the crop productivity. Crop plants exhibit tolerance and susceptibility under adverse conditions through various attributes at different levels like morphological, physiological, biochemical and genetic level, although their magnitude of response varies. Crops responses toward abiotic stresses have increased in the recent years by advancement of technology and understanding of physiology, molecular and genetic level of crops response to these stresses. In the processes of development of stress-tolerant plants, several genes associated tolerance and adaptation get activated leading to modulate several biochemical, physiological and metabolic pathways. Stress also induces the production of reactive oxygen species (ROS) and subsequently change in signal transduction in the plants switches towards enhancement of antioxidant system. Both abiotic and biotic stresses affect all the physiological processes of the legume plants, especially photosynthesis, respiration, water use efficiency, nutrient use efficiency etc. The activity of cell organelles like mitochondria, chloroplast and vacuoles is also affected by stress. The present study is focusing on the impact of diverse abiotic stresses at different levels in legume crops and changes at physiological, biochemical and molecular level. It also discusses the opportunities to ameliorate the ability of the legumes to enhance abiotic stress tolerance for crop improvement and agriculture sustainability.

Alleviation role of exogenous cadaverine on cell cycle, endogenous polyamines amounts and biochemical enzyme changes in barley seedlings under drought stress

Cadaverine (Cad), which has an independent synthesis pathway compared to other polyamine (PA) types, contributes to the health of plants by regulating plant growth and development, abiotic stress tolerance and antioxidant defense mechanisms. In this work, experiments were carried out to understand the effects of exogenous Cad (10 µM) application under drought stress (%22 PEG 6000) and without stress on cell cycle, total protein content, endogenous PA levels, and biochemical enzyme activities in barley (Hordeum vulgare cv. Burakbey) considering the potential of Cad to stimulate the drought-related tolerance system. Cad application in a stress-free environment showed an effect almost like low-impact drought stress, causing changes in all parameters examined compared to samples grown in distilled water environment (Control). The results clearly show that Cad applied against the negative effects of drought stress on all parameters creates a drought resistance mechanism of the plant. Accordingly, Cad applied together with drought stress increased the density of cells in the cell cycle (G1–S and S–G2 phases) and the amount of endogenous (spermidine 10% and spermine 40%) PAs. In addition, while superoxide dismutase (SOD) (5%), (CAT) (55%) and ascorbate peroxidase (APX) (18%) enzyme levels increased, a stress response mechanism occurred due to the decrease in total protein content (20%) and malondialdehyde (MDA) (80%). As a result, exogenous application of 10 µM Cad showed that it reduced the negative effects of drought stress on endogenous PA amounts, cell division and biochemical activities in barley.

CGMP functions as an important messenger involved in SlSAMS1-regulated salt stress tolerance in tomato

Salt stress adversely affects the growth, development, and yield of tomato (Solanum lycopersicum). SAM Synthetase (SAMS), which is responsible for the biosynthesis of S-adenosylmethionine (SAM, a precursor of polyamine biosynthesis), participates in plant response to abiotic stress. However, the regulatory mechanism of SAMS-mediated salt stress tolerance remains elusive. In this study, we characterized a SAMS homologue SlSAMS1 in tomato. We found that SlSAMS1 is highly expressed in tomato roots, and its expression can be induced by salt stress. Crucially, overexpression of SlSAMS1 in tomato enhances salt stress tolerance. Through metabolomic profiling, we identified some differentially accumulated metabolites, especially, a secondary messenger guanosine 3′,5′-cyclic monophosphate (cGMP) which may play a key role in SlSAMS1-regulated salt tolerance. A series of physiological and biochemical data suggest that cGMP alleviates salt stress-induced growth inhibition, and potentially acts downstream of the polyamine-nitric oxide (PA-NO) signaling pathway to trigger H2O2 signaling in response to salt stress. Taken together, the study reveals that SlSAMS1 regulates tomato salt tolerance via the PA–NO–cGMP-H2O2 signal module. Our findings elucidate the regulatory pathway of SlSAMS1-induced plant response to salt stress and indicate a pivotal role of cGMP in salt tolerance.

Establishment of an Efficient and Rapid Regeneration System for a Rare Shrubby Desert Legume Eremosparton songoricum.

Eremosparton songoricum (Litv.) Vass. is a rare and extremely drought-tolerant legume shrub that is distributed in Central Asia. E. songoricum naturally grows on bare sand and can tolerate multiple extreme environmental conditions. It is a valuable and important plant resource for desertification prevention and environmental protection, as well as a good material for the exploration of stress tolerance mechanisms and excellent tolerant gene mining. However, the regeneration system for E. songoricum has not yet been established, which markedly limits the conservation and utilization of this endangered and valuable desert legume. Assimilated branches derived from seedlings were cultured on several MS mediums supplemented with various concentrations of TDZ or 6-BA in different combinations with NAA. The results showed that the most efficient multiplication medium was MS medium supplemented with 0.4 mg/L 6-BA and 0.1 mg/L NAA. The most efficient rooting medium was WPM + 25 g/L sucrose. The highest survival rate (77.8%) of transplantation was achieved when the ratio of sand to vermiculite was 1:1. In addition, the optimal callus induction medium was MS + 30 g/L sucrose + 2 mg/L TDZ + 0.5 mg/L NAA in darkness. The E. songoricum callus treated with 100 mM NaCl and 300 mM mannitol on MS medium could be used in proper salt and drought stress treatments in subsequent gene function tests. A rapid and efficient regeneration system for E. songoricum that allowed regeneration within 3 months was developed. The protocol will contribute to the conservation and utilization of this rare and endangered desert stress-tolerant species and also provide a fundamental basis for gene functional analysis in E. songoricum.

TaGPX1-D overexpression provides salinity and osmotic stress tolerance in Arabidopsis

Glutathione peroxidases (GPXs) are known to play an essential role in guarding cells against oxidative stress by catalyzing the reduction of hydrogen peroxide and organic hydroperoxides. The current study aims functional characterization of the TaGPX1-D gene of bread wheat (Triticum aestivum) for salinity and osmotic stress tolerance. To achieve this, we initially performed the spot assays of TaGPX1-D expressing yeast cells. The growth of recombinant TaGPX1-D expressing yeast cells was notably higher than the control cells under stress conditions. Later, we generated transgenic Arabidopsis plants expressing the TaGPX1-D gene and investigated their tolerance to various stress conditions. The transgenic plants exhibited improved tolerance to both salinity and osmotic stresses compared to the wild-type plants. The higher germination rates, increased antioxidant enzymes activities, improved chlorophyll, carotenoid, proline and relative water contents, and reduced hydrogen peroxide and MDA levels in the transgenic lines supported the stress tolerance mechanism. Overall, this study demonstrated the role of TaGPX1-D in abiotic stress tolerance, and it can be used for improving the tolerance of crops to environmental stressors, such as salinity and osmotic stress in future research.

Identification of genes associated with abiotic stress tolerance in sweetpotato using weighted gene co-expression network analysis.

Sweetpotato, Ipomoea batatas (L.), a key food security crop, is negatively impacted by heat, drought, and salinity stress. The orange-fleshed sweetpotato cultivar "Beauregard" was exposed to heat, salt, and drought treatments for 24 and 48 h to identify genes responding to each stress condition in leaves. Analysis revealed both common (35 up regulated, 259 down regulated genes in the three stress conditions) and unique sets of up regulated (1337 genes by drought, 516 genes by heat, and 97 genes by salt stress) and down regulated (2445 genes by drought, 678 genes by heat, and 204 genes by salt stress) differentially expressed genes (DEGs) suggesting common, yet stress-specific transcriptional responses to these three abiotic stressors. Gene Ontology analysis of down regulated DEGs common to both heat and salt stress revealed enrichment of terms associated with "cell population proliferation" suggestive of an impact on the cell cycle by the two stress conditions. To identify shared and unique gene co-expression networks under multiple abiotic stress conditions, weighted gene co-expression network analysis was performed using gene expression profiles from heat, salt, and drought stress treated 'Beauregard' leaves yielding 18 co-expression modules. One module was enriched for "response to water deprivation," "response to abscisic acid," and "nitrate transport" indicating synergetic crosstalk between nitrogen, water, and phytohormones with genes encoding osmotin, cell expansion, and cell wall modification proteins present as key hub genes in this drought-associated module. This research lays the groundwork for exploring to a further degree, mechanisms for abiotic stress tolerance in sweetpotato.

Salicylic acid alleviates Zn-induced inhibition of growth via enhancing antioxidant system and glutathione metabolism in alfalfa

Zinc (Zn) is considered as one of the heavy metal pollutants in soil affecting agriculture. Salicylic acid (SA) is an important phytohormone that can mitigate effects against various abiotic stresses in plants, however, its exploration to improve Zn stress tolerance in alfalfa plants is still elusive. Thus, in the present study, exogenous SA treatment was conducted on alfalfa plants under Zn stress. The effects of exogenous SA on the physiological effects of alfalfa plants and the expression levels related genes were studied. This study tested the biomass, relative water content, chlorophyll levels, photosynthetic capacity, proline and soluble sugar contents, detected the activity of antioxidant enzymes (such as peroxidase and superoxide dismutase), glutathione biosynthesis, and endogenous SA levels, and quantified the genes associated with the antioxidant system and glutathione metabolism-mediated Zn stress. The results showed that exogenous SA could elevate the physiological adaptability of alfalfa plants through enhancing photosynthesis, proline and soluble sugar levels, stimulating antioxidant system and glutathione metabolism, and inducing the transcription level of related genes, thereby diminishing oxidative stress, inhibiting excessive Zn accumulation of alfalfa plants, increasing tolerance to Zn stress, and reducing the toxicity of Zn. Collectively, the application of SA alleviates Zn toxicity in alfalfa plants. The findings gave first insights into the regulatory mechanism of the Zn stress tolerance of alfalfa by exogenous SA and this might have positive implications for managing other plants which are suffering Zn stress.

Plants Stress: Salt Stress and Mechanisms of Stress Tolerance

A diverse combination of biotic and abiotic pressures makes up the environment that plants naturally inhabit. These pressures cause similarly complicated responses in plants. The purpose of the review is to critically evaluate the effects of various stress stimuli on higher plants with an emphasis on the typical and distinctive dose-dependent responses that are essential for plant growth and development. In order to improve agricultural productivity, breed new salt-tolerant cultivars, and make the most of saline land, it is essential to comprehend the mechanisms underlying plant salt tolerance. Soil salinization has emerged as a global problem. Locating regulatory centres in complex networks is made possible by systems biology techniques, enabling a multi-targeted approach. The goal of systems biology is to organise the molecular constituents of an organism (transcripts, proteins, and metabolites) into functioning networks or models that describe and forecast the dynamic behaviours of that organism in diverse contexts. This review focuses on the molecular, physiological, and pharmacological mechanisms that underlie how stress affects genomic instability, including DNA damage. Additionally, a summary of the physiological mechanisms behind salt tolerance, including the removal of reactive oxygen species (ROS) and osmotic adjustment, has been provided. The salt overly sensitive (SOS), calcium-dependent protein kinase (CDPK), mitogen-activated protein kinase (MAPKs), and abscisic acid (ABA) pathways are the four main signalling pathways for stress. According to earlier research, salt stress causes harm to plants by inhibiting photosynthesis, upsetting ion homeostasis, and peroxiding membranes. listed a few genes that are sensitive to salt stress and correspond to physiological systems. The review describes the most recent tactics and procedures for boosting salt tolerance in plants. We can make predictions about how plants will behave in the field and better understand how they respond to different levels of stress by understanding both the positive and negative aspects of stress responses, including genomic instability. The new knowledge can be put to use to enhance crop productivity and develop more resilient plant kinds, ensuring a consistent supply of food for the global population, which is currently undergoing rapid expansion.

Omics for Elucidating Heat Stress Tolerance Mechanisms in Wheat: A Review Update

For the vast majority of people on earth, wheat is a primary staple food crop. It is one of the most vulnerable crops, the production of which significantly suffers from the harmful effects of climate change. As the predicted increase in global temperature is supposed to jeopardize production, wheat improvement towards heat stress-resilience has gained pivotal importance. The large and complex allohexaploid wheat genome represents a genetic puzzle, where deciphering any trait-genetics is always challenging. Fortunately, the advancement in the ‘omics’ approach has paved the way for solving these issues in a multidisciplinary convergent manner. The approach has significantly contributed towards the complex molecular mechanisms of the heat stress tolerance in wheat. In the recent past, salient attainments have been observed in exploring heat tolerance mechanisms in wheat addressed through omics technologies. All these approaches have identified some of the key regulators behind this complex trait, the conglomeration of which is definitely promising for achieving heat tolerant cultivars. Besides, the epigenetic regulation of this important trait as well as the significant achievements in developing heat tolerant lines through a transgenic approach has been enumerated. This summarized review of an issue of global importance should enlighten the understanding of the complex regulation of heat tolerance mechanism in wheat, which is a prerequisite for the development of stable heat tolerant wheat cultivars in near future. Here we discussed current research on the genetic and molecular variables that alter one's ability to tolerate heat, including the effects of epigenetic regulation. At the end, we concluded the review by discussing integrative methods for enhancing heat tolerance through the use of current germplasm, such as contemporary cultivars, landraces, and related species.