Polyethylene Glycol Treatment Research Articles

Drought stress effects on Lathyrus seedlings: A morpho-physiological and molecular study

The experiment aimed to investigate the impact of polyethylene glycol (PEG) treatments, specifically 0% (control), 15% (PEG-I), and 20% (PEG-II), on various seed quality traits, proline content, and morpho-physiological traits at both the seed (9 days) and seedling stage (18 days) in five Lathyrus genotypes and to relate the ISSR markers based molecular characterization of these genotypes osmotic stress. The results unveiled substantial phenotypic and molecular diversity among the accessions concerning morpho-physiological and seed quality traits. Ratan variety exhibited promise as it demonstrated a higher germination percentage (G%) at 62.78±2.42% for PEG-I and 13.33±0.10% for PEG-II, along with a lower mean germination time (MGT) of 3.80±0.071 days for PEG-I and 7.33±0.16 days for PEG-II. P-24 showcased the highest seed vigour index-I (SVI-I) at 872.06±27.02 for PEG-I, whereas Nirmal recorded the highest SVI-I at 80.03±8.53 for PEG-II. Notably, Nirmal displayed the lowest proline content, expressed as μmol per gram of fresh weight (52.45±6.27 units for PEG-I and 111.37±4.75 units for PEG-II) at the seed stage. For the seedling stage, Ratan exhibited the lowest proline content, expressed as μmol per gram of fresh weight (14.18±1.09 units for PEG-I and 10.67±0.851 units for PEG-II). Prateek demonstrated higher seedling length (42.00±1.44 cm for PEG-I and 45.88±0.30 cm for PEG-II), as well as root length (14.11±0.84 cm for PEG-I and 21.29±1.59 cm). Principal component analysis (PCA) highlighted that the most influential variables contributing to the highest variability in the PCA included SVI-I, MGT, and seedling length. Molecular characterization employing ISSR markers resulted in three clusters: CI (Ratan), CII (Pusa-24 and Mahateora), and CIII (Prateek and Nirmal), based on the genetic similarity coefficient. These genotypes exhibit the potential to be recommended and utilized in breeding programs for developing drought-tolerant Lathyrus germplasm.

TabHLH27 orchestrates root growth and drought tolerance to enhance water use efficiency in wheat.

Cultivating high-yield wheat under limited water resources is crucial for sustainable agriculture in semiarid regions. Amid water scarcity, plants activate drought response signaling, yet the delicate balance between drought tolerance and development remains unclear. Through genome-wide association studies and transcriptome profiling, we identified a wheat atypical basic helix-loop-helix (bHLH) transcription factor (TF), TabHLH27-A1, as a promising quantitative trait locus candidate for both relative root dry weight and spikelet number per spike in wheat. TabHLH27-A1/B1/D1 knock-out reduced wheat drought tolerance, yield, and water use efficiency (WUE). TabHLH27-A1 exhibited rapid induction with polyethylene glycol (PEG) treatment, gradually declining over days. It activated stress response genes such as TaCBL8-B1 and TaCPI2-A1 while inhibiting root growth genes like TaSH15-B1 and TaWRKY70-B1 under short-term PEG stimulus. The distinct transcriptional regulation of TabHLH27-A1 involved diverse interacting factors such as TaABI3-D1 and TabZIP62-D1. Natural variations of TabHLH27-A1 influence its transcriptional responses to drought stress, with TabHLH27-A1Hap-II associated with stronger drought tolerance, larger root system, more spikelets, and higher WUE in wheat. Significantly, the excellent TabHLH27-A1Hap-II was selected during the breeding process in China, and introgression of TabHLH27-A1Hap-II allele improved drought tolerance and grain yield, especially under water-limited conditions. Our study highlights TabHLH27-A1's role in balancing root growth and drought tolerance, providing a genetic manipulation locus for enhancing WUE in wheat.

Identification of the Gossypium hirsutum SDG Gene Family and Functional Study of GhSDG59 in Response to Drought Stress.

SET-domain group histone methyltransferases (SDGs) are known to play crucial roles in plant responses to abiotic stress. However, their specific function in cotton's response to drought stress has not been well understood. This study conducted a comprehensive analysis of the SDG gene family in Gossypium hirsutum, identifying a total of 82 SDG genes. An evolutionary analysis revealed that the SDG gene family can be divided into eight subgroups. The expression analysis shows that some GhSDG genes are preferentially expressed in specific tissues, indicating their involvement in cotton growth and development. The transcription level of some GhSDG genes is induced by PEG, with GhSDG59 showing significant upregulation upon polyethylene glycol (PEG) treatment. Quantitative polymerase chain reaction (qPCR) analysis showed that the accumulation of transcripts of the GhSDG59 gene was significantly upregulated under drought stress. Further functional studies using virus-induced gene silencing (VIGS) revealed that silencing GhSDG59 reduced cotton tolerance to drought stress. Under drought conditions, the proline content, superoxide dismutase (SOD) and peroxidase (POD) enzyme activities in the GhSDG59-silenced plants were significantly lower than in the control plants, while the malondialdehyde (MDA) content was significantly higher. Transcriptome sequencing showed that silencing the GhSDG59 gene led to significant changes in the expression levels of 1156 genes. The KEGG enrichment analysis revealed that these differentially expressed genes (DEGs) were mainly enriched in the carbon metabolism and the starch and sucrose metabolism pathways. The functional annotation analysis identified known drought-responsive genes, such as ERF, CIPK, and WRKY, among these DEGs. This indicates that GhSDG59 is involved in the drought-stress response in cotton by affecting the expression of genes related to the carbon metabolism and the starch and sucrose metabolism pathways, as well as known drought-responsive genes. This analysis provides valuable information for the functional genomic study of SDGs and highlights potential beneficial genes for genetic improvement and breeding in cotton.

Appropriate Drought Training Induces Optimal Drought Tolerance by Inducing Stepwise H2O2 Homeostasis in Soybean.

Soybean is considered one of the most drought-sensitive crops, and ROS homeostasis can regulate drought tolerance in these plants. Understanding the mechanism of H2O2 homeostasis and its regulatory effect on drought stress is important for improving drought tolerance in soybean. We used different concentrations of polyethylene glycol (PEG) solutions to simulate the progression from weak drought stress (0.2%, 0.5%, and 1% PEG) to strong drought stress (5% PEG). We investigated the responses of the soybean plant phenotype, ROS level, injury severity, antioxidant system, etc., to different weak drought stresses and subsequent strong drought stresses. The results show that drought-treated plants accumulated H2O2 for signaling and exhibited drought tolerance under the following stronger drought stress, among which the 0.5% PEG treatment had the greatest effect. Under the optimal treatment, there was qualitatively describable H2O2 homeostasis, characterized by a consistent increasing amplitude in H2O2 content compared with CK. The H2O2 signal formed under the optimum treatment induced the capacity of the antioxidant system to remove excess H2O2 to form a primary H2O2 homeostasis. The primary H2O2 homeostasis further induced senior H2O2 homeostasis under the following strong drought and maximized the improvement of drought tolerance. These findings might suggest that gradual drought training could result in stepwise H2O2 homeostasis to continuously improve drought tolerance.

Verification of the peanut vitamin C synthesis-related gene AhPMM and its role in stress resistance

Vitamin C plays an important role in plant antioxidation, photosynthesis, growth and development, and metabolism. In this study, a gene AhPMM, which is involved in vitamin C synthesis and responds significantly to low temperature, NaCl, polyethylene glycol (PEG) and abscisic acid (ABA) treatments, was cloned from peanut. An AhPMM overexpression vector was constructed, and transferred to a peanut variety Junanxiaohong using the pollen tube injection method. PCR test on the T3 generation transgenic peanut plants showed a transgenics positive rate of 42.3%. HPLC was used to determine the content of reducing vitamin C (AsA) and total vitamin C in the leaves of transgenic plants. The results showed that the content of AsA in some lines increased significantly, up to 1.90 times higher than that of the control, and the total vitamin content increased by up to 1.63 times compared to that of the control. NaCl and ABA tolerance tests were carried out on transgenic seeds. The results showed that the salt tolerance of transgenic seeds was significantly enhanced and the sensitivity to ABA was weakened compared to that of the non-transgenic control. Moreover, the salt tolerance of the transgenic plants was also significantly enhanced compared to that of the non-transgenic control. The above results showed that AhPMM gene not only increased the vitamin C content of peanut, but also increased the salt tolerance of transgenic peanut seeds and plants. This study may provide a genetic source for the molecular breeding of peanut for enhanced salt tolerance.

The A subunit of vacuolar H+-ATPase gene (CmVHA-A) plays opposite roles in plant growth and drought tolerance of chrysanthemum under different growing conditions

As the most prominent proton pumps in plants, vacuolar H+-ATPases (VHAs) comprise multiple subunits that are important for physiological processes and stress tolerance in plants. However, few studies on the roles of subunit genes of VHAs in chrysanthemum have been reported to date. In this study, the gene of A subunit of V-ATPase in chrysanthemum (CmVHA-A) was cloned and identified. CmVHA-A was conserved with VHA-A proteins from other plants. Expression analysis showed that CmVHA-A was highly expressed in most tissues of chrysanthemum except for the flower bud, and was readily induced by polyethylene glycol (PEG) treatment. Functional analysis demonstrated that CmVHA-A exerted a negative influence on the growth and development of shoot and root of chrysanthemum under normal conditions. RNA-sequencing (RNA-seq) analysis revealed the possible explanations for phenotypic differences between transgenic and wild-type (WT) plants. Under drought conditions, CmVHA-A positively affected the drought tolerance of chrysanthemum by enhancing antioxidase activity and alleviating photosynthetic disruption. Overall, CmVHA-A plays opposite roles in plant growth and drought tolerance of chrysanthemums under different growing conditions.

Water-deficit stress induces prenylated stilbenoid production and affects biomass in peanut hairy roots: Exploring the role of stilbenoid prenyltransferase downregulation

The peanut plant is one of the most economically important crops around the world. Abiotic stress, such as drought, causes over five hundred million dollars in losses in peanut production per year. Peanuts are known to produce prenylated stilbenoids to counteract biotic stress. However, their role in abiotic stress tolerance has not been elucidated. To address this issue, hairy roots with the capacity to produce prenylated stilbenoids were established. An RNA-interference (RNAi) molecular construct targeting the stilbenoid-specific prenyltransferase AhR4DT-1 was designed and expressed via Agrobacterium rhizogenes-mediated transformation in hairy roots of peanut cultivar Georgia Green. Two transgenic hairy roots with the RNAi molecular construct were established, and the downregulation of AhR4DT-1 was validated using reverse transcriptase quantitative PCR. To determine the efficacy of the RNAi-approach in modifying the levels of prenylated stilbenoids, the hairy roots were co-treated with methyl jasmonate, hydrogen peroxide, cyclodextrin, and magnesium chloride to induce the production of stilbenoids and then the stilbenoids were analyzed in extracts of the culture medium. Highly reduced levels of prenylated stilbenoids were observed in the RNAi hairy roots. Furthermore, the hairy roots were evaluated in a polyethylene glycol (PEG) assay to assess the role of prenylated stilbenoids on water-deficit stress. Upon PEG treatment, stilbenoids were induced and secreted into the culture medium of RNAi and wild-type hairy roots. Additionally, the biomass of the RNAi hairy roots decreased by a higher amount as compared to the wild-type hairy roots suggesting that prenylated stilbenoids might play a role against water-deficit stress.

The miR166 targets CsHDZ3 genes to negatively regulate drought tolerance in tea plant (Camellia sinensis)

Drought is the stressor with a significant adverse impact on the yield stability of tea plants. HD-ZIP III transcription factors (TFs) play important regulatory roles in plant growth, development, and stress responses. However, whether and how HD-ZIP III TFs are involved in drought response and tolerance in tea plants remains unclear. Here, we identified seven HD-ZIP III genes (CsHDZ3–1 to CsHDZ3–7) in tea plant genome. The evolutionary analysis demonstrated that CsHDZ3 members were subjected to purify selection. Subcellular localization analysis revealed that all seven CsHDZ3s located in the nucleus. Yeast self-activation and dual-luciferase reporter assays demonstrated that CsHDZ3–1 to CsHDZ3–4 have trans-activation ability whereas CsHDZ3–5 to CsHDZ3–7 served as transcriptional inhibitors. The qRT-PCR assay showed that all seven CsHDZ3 genes could respond to simulated natural drought stress and polyethylene glycol treatment. Further assays verified that all CsHDZ3 genes can be cleaved by csn-miR166. Overexpression of csn-miR166 inhibited the expression of seven CsHDZ3 genes and weakened drought tolerance of tea leaves. In contrast, suppression of csn-miR166 promoted the expression of seven CsHDZ3 genes and enhanced drought tolerance of tea leaves. These findings established the foundation for further understanding the mechanism of CsHDZ3-miR166 modules' participation in drought responses and tolerance.

Genome-wide identification, gene expression and haplotype analysis of the rhomboid-like gene family in wheat (Triticum aestivum L.).

The rhomboid-like (RBL) gene encodes serine protease, which plays an important role in the response to cell development and diverse stresses. However, genome-wide identification, expression profiles, and haplotype analysis of the RBL family genes have not been performed in wheat (Triticum aestivum L.). This study investigated the phylogeny and diversity of the RBL family genes in the wheat genome through various approaches, including gene structure analysis, evolutionary relationship analysis, promoter cis-acting element analysis, expression pattern analysis, and haplotype analysis. The 41 TaRBL genes were identified and divided into five subfamilies in the wheat genome. RBL family genes were expanded through segmented duplication and purification selection. The cis-element analysis revealed their involvement in various stress responses and plant development. The results of RNA-seq and quantitative real-time-PCR showed that TaRBL genes displayed higher expression levels in developing spike/grain and were differentially regulated under polyethylene glycol, NaCl, and abscisic acid treatments, indicating their roles in grain development and abiotic stress response. A kompetitive allele-specific PCR molecular marker was developed to confirm the single nucleotide polymorphism of TaRBL14a gene in 263 wheat accessions. We found that the elite haplotype TaRBL14a-Hap2 showed a significantly higher 1000-grain weight than TaRBL14a-Hap11 in at least three environments, and the TaRBL14a-Hap2 was positively selected in wheat breeding. The findings will provide a good insight into the evolutionary and functional characteristics of the TaRBL genes family in wheat and lay the foundation for future exploration of the regulatory mechanisms of TaRBL genes in plant growth and development, as well as their response to abiotic stresses.

Evaluation of Suitable Reference Genes for Quantitative Real-Time PCR in Various Tissues of Apocynum venetum.

Apocynum venetum L. is an economically valuable plant with tolerance to drought and salinity. Its leaves are utilized in tea production and pharmaceuticals, while the stem bark serves as a high-quality fiber material. To gain insights into the gene expression patterns of A. venetum using quantitative real-time PCR (qRT-PCR), it is crucial to identify appropriate reference genes. This study selected nine candidate genes, including α-tubulin (TUA), β-tubulin (TUB), actin (ACT), cyclophilin (CYP), elongation factor-1α (EF-1α), the B family of regulatory subunits of protein phosphatase (PPP2R2, PPP2R3, and PPP2R5), and phosphoglycerate kinase (PGK), to determine the most appropriate reference genes in the leaf, stem, and root tissues of A. venetum. A comprehensive ranking by geNorm, NormFinder, BestKeeper, and RefFinder software and Venn diagrams was used to screen more stable reference genes in different tissues. The two most stable reference genes were CYP and TUA in leaves, PGK and PPP2R3 in stems, and TUA and EF-1α in roots, respectively. The relative expression values of the four genes involved in proline metabolism under polyethylene glycol treatment were used to validate the screened reference genes, and they exhibited highly stable expression levels. These findings represent the first set of stable reference genes for future gene expression studies in A. venetum. They significantly contribute to enhancing the accuracy and reliability of gene expression analyses in this economically important plant species.

Genotype-specific germination behavior induced by sustainable priming techniques in response to water deprivation stress in rice.

Water stress brought about by climate change is among the major global concerns threatening food security. Rice is an important staple food which requires high water resources. Being a semi-aquatic plant, rice is particularly susceptible to drought. The aim of this work was to develop techniques directed to promote rice resilience to water deprivation stress during germination by implementing specific seed priming treatments. Five popular Italian rice varieties were subjected to priming treatments using novel, sustainable solutions, like poly-gamma-glutamic acid (γ-PGA), denatured γ-PGA (dPGA), and iron (Fe) pulsing, alone or in combination. The effect of the developed priming methods was tested under optimal conditions as well as under water deprivation stress imposed by polyethylene glycol (PEG) treatments. The priming efficacy was phenotypically determined in terms of germination behavior by measuring a series of parameters (germinability, germination index, mean germination time, seed vigor index, root and shoot length, germination stress tolerance index). Biochemical analyses were carried out to measure the levels of iron uptake and accumulation of reactive oxygen species (ROS). Integrative data analyses revealed that the rice varieties exhibited a strong genotype- and treatment-specific germination behavior. PEG strongly inhibited germination while most of the priming treatments were able to rescue it in all varieties tested except for Unico, which can be defined as highly stress sensitive. Molecular events (DNA repair, antioxidant response, iron homeostasis) associated with the transition from seed to seedling were monitored in terms of changes in gene expression profiles in two varieties sensitive to water deprivation stress with different responses to priming. The investigated genes appeared to be differentially expressed in a genotype-, priming treatment-, stress- and stage-dependent manner. The proposed seed priming treatments can be envisioned as sustainable and versatile agricultural practices that could help in addressing the impact of climate challenges on the agri-food system.

The physiology and anatomy study in leaves of Saragolla and Svevo wheat cultivars under polyethylene glycol-simulated drought stress.

Drought stress is increasing in frequency and severity with the progression of global climate change, thereby becoming a major concern for the growth and yield of crop plants, including wheat. The current challenge is to explore different ways of developing wheat genotypes with increased tolerance to drought. Therefore, we renewed interest in 'ancient' varieties expected to be more tolerant to environmental stress than the few elite varieties nowadays cultivated. This study aimed to perform comparative analysis of the effect of drought-simulating polyethylene glycol (PEG-6000) treatment on morpho-anatomical and physiological foliar traits of two durum wheat seedlings cultivars, Saragolla and Svevo, as these can reflect the adaptability of the plant to the environment to a certain extent. Results demonstrated that drought-stressed Saragolla leaves exhibited a greater reduction of stomatal density, a minor reduction of stomatal pore width, a wider xylem vessel mean area, greater compactness of mesophyll cells, a minor loss of chlorophyll content, as well as better photosynthetic and growth performance compared to the other variety. From such behaviours, we consider the Saragolla cultivar more drought tolerant than Svevo and therefore probably very promising for cultivation in dry areas.

Genome-wide analysis of PvMADS in common bean and functional characterization of PvMADS31 in Arabidopsis thaliana as a player in abiotic stress responses.

Changing climatic conditions with rising temperatures and altered precipitation patterns pose significant challenges to agricultural productivity, particularly for common bean crops. Transcription factors (TFs) are crucial regulators that can mitigate the impact of biotic and abiotic stresses on crop production. The MADS-box TFs family has been implicated in various plant physiological processes, including stress-responsive mechanisms. However, their role in common bean and their response to stressful conditions remain poorly understood. Here, we identified 35 MADS-box gene family members in common bean, with conserved MADS-box domains and other functional domains. Gene duplication events were observed, suggesting the significance of duplication in the evolutionary development of gene families. The analysis of promoter regions revealed diverse elements, including stress-responsive elements, indicating their potential involvement in stress responses. Notably, PvMADS31, a member of the PvMADS-box gene family, demonstrated rapid upregulation under various abiotic stress conditions, including NaCl, polyethylene glycol, drought, and abscisic acid (ABA) treatments. Transgenic plants overexpressing PvMADS31 displayed enhanced lateral root development, root elongation, and seed germination under stress conditions. Furthermore, PvMADS31 overexpression in Arabidopsis resulted in improved drought tolerance, likely attributed to the enhanced scavenging of ROS and increased proline accumulation. These findings suggest that PvMADS31 might play a crucial role in modulating seed germination, root development, and stress responses, potentially through its involvement in auxin and ABA signaling pathways. Overall, this study provides valuable insights into the potential roles of PvMADS-box genes in abiotic stress responses in common bean, offering prospects for crop improvement strategies to enhance resilience under changing environmental conditions.

IbNIEL-mediated degradation of IbNAC087 regulates jasmonic acid-dependent salt and drought tolerance in sweet potato.

Sweet potato (Ipomoea batatas [L.] Lam.) is a crucial staple and bioenergy crop. Its abiotic stress tolerance holds significant importance in fully utilizing marginal lands. Transcriptional processes regulate abiotic stress responses, yet the molecular regulatory mechanisms in sweet potato remain unclear. In this study, a NAC (NAM, ATAF1/2, and CUC2) transcription factor, IbNAC087, was identified, which is commonly upregulated in salt- and drought-tolerant germplasms. Overexpression of IbNAC087 increased salt and drought tolerance by increasing jasmonic acid (JA) accumulation and activating reactive oxygen species (ROS) scavenging, whereas silencing this gene resulted in opposite phenotypes. JA-rich IbNAC087-OE (overexpression) plants exhibited more stomatal closure than wild-type (WT) and IbNAC087-Ri plants under NaCl, polyethylene glycol, and methyl jasmonate treatments. IbNAC087 functions as a nuclear transcriptional activator and directly activates the expression of the key JA biosynthesis-related genes lipoxygenase (IbLOX) and allene oxide synthase (IbAOS). Moreover, IbNAC087 physically interacted with a RING-type E3 ubiquitin ligase NAC087-INTERACTING E3 LIGASE (IbNIEL), negatively regulating salt and drought tolerance in sweet potato. IbNIEL ubiquitinated IbNAC087 to promote 26S proteasome degradation, which weakened its activation on IbLOX and IbAOS. The findings provide insights into the mechanism underlying the IbNIEL-IbNAC087 module regulation of JA-dependent salt and drought response in sweet potato and provide candidate genes for improving abiotic stress tolerance in crops.

<em>In Vitro</em> Effect of PEG and Proline on Callus Growth and Minerals Values in Basmati Rice (<em>Oryza sativa</em>)

Purpose: Drought is a universal issue that disturbs photosynthetic system, adversely affecting quality and crop yield. The study was conducted to determine response of polyethylene glycol (PEG) as stressing agent alone or combination with proline on four fine rice genotypes for callus components as well as biochemical parameters like Chromium (Cr), Magnesium (Mg), Manganese (Mn), Iron (Fe), Phosphorus (P).Research Method: Callus was induced on media having 4.43g/L MS + 4mg/L 2, 4-D (2, 4-dichlorophenoxy acetic acid) + 30g/L sucrose + 1.76g/L phytagel with different levels of PEG “1.25g/L and 2.5g/L” with and without 1ml/L proline.Findings: Callus was used for different analyses after 30 days and results showed that PEG treatments have a negative effect on callus fresh weight, callus dry weight, days to callus induction, callus percentage, and mineral nutrients like K, Cr, Mg, Mn, Fe, P. PEG 2.5g/L showed a greater decrease as compared to PEG 1.25g/L. Proline significantly raises callus growth alone or in combination with PEG but less than control whereas callus dry weight, K, and Ca contents increased more than control when proline applied alone or with PEG combination.Originality/value: Exogenous proline application improves callus growth rate as well as macro- micro elements by mitigating the effect of PEG.

Physiological, agro-morphological, and germination responses of a worldwide chickpea (Cicer arietinum) collection subjected to drought stress by applying polyethylene glycol (PEG) on germinating seeds and by exposure plants to water restriction at the vegetative stage

Given that agriculture uses considerable quantities of water to meet food requirements, the scarcity of rainfall and the drying up of water tables could compromise agricultural production. Faced with the urgency of a world undergoing demographic change and a current agro-climatic trend marked by low rainfall at the vegetative stage, the sustainability of chickpea production requires new varieties with resilience and adaptation to climatic change. The aim of this study is the selection genotypes that are tolerant to early drought stress and able to avoid terminal drought. To this end, a collection of 159 genotypes was evaluated, using an augmented-RCBD (Randomized Complete Block Designs), in two experiments (drought stress by water restriction and stress imposition by Polyethylene glycol (PEG) application) simulating the effect of drought. Our results show significant genetic variability and a fairly significant genotype effect in both trials. We noted an interesting positive correlation between germination percentage in the presence of PEG and pod and seed production under water stress at the vegetative stage, and these same traits showed strong heritability. 16 genotypes had a germination percentage ≥50% in the 20% PEG treatment. In addition, 18 Desi and 4 Kabuli genotypes performed well in both trials, with good germination percentage, pod and seed production, good canopy coverage, better normalized difference vegetation index, and low to medium wilting. It would therefore make sense to exploit these genotypes in hybridization programs for the creation of pure drought-tolerant lines, and also to evaluate them in different arid and semi-arid regions over several years.

Drought tolerance selection of several tomato varieties by using polyethylene glycol

A prolonged dry season can cause drought stress and have an unfavorable impact on the growth of tomato plants, resulting in crop failure. Therefore, research is needed on the resistance of tomato varieties to drought stress. The recommended technique for drought resistance screening in tomatoes is in vitro cultivation using Polyethylene Glycol (PEG). The research aimed to obtain new varieties that could be used as promising lines for varieties tolerant to drought stress. The research method used included using ingredients in the form of 5 varieties of tomatoes (Ratna, Intan, Chung, Palupi, and Amelia) and 5 concentrations of PEG chemicals (0%, 5%, 10%, 15%, and 20%). Each seed of each tomato variety that had been sterilized using hypochlorite was germinated on MS0 media, then the germinated seeds with a size of ± 0.3 cm were transferred to MS0 + PEG treatment medium with each treatment concentration. The seeds that had been planted on the PEG-treated medium were then observed for growth for ± 4 weeks. The research data were analyzed using analysis of variance (ANOVA) and followed with DMRT at the 5% significance level. Based on the results, Palupi variety is the most tolerant variety, and Ratna variety is the most intolerant variety to drought stress. The higher the concentration of PEG used, the more it inhibits plant height, root length, and fresh weight of the roots.

Rice OsANN9 Enhances Drought Tolerance through Modulating ROS Scavenging Systems.

Drought is a critical abiotic stress which leads to crop yield and a decrease in quality. Annexins belong to a multi-gene family of calcium- and lipid-binding proteins and play diverse roles in plant growth and development. Herein, we report a rice annexin protein, OsANN9, which in addition to regular annexin repeats and type-II Ca2+ binding sites, also consists of a C2H2-type zinc-finger domain. We found that the expression of OsANN9 was upregulated by polyethylene glycol (PEG) or water-deficient treatment. Moreover, plants that overexpressed OsANN9 had increased survival rates under drought stress, while both OsANN9-RNAi and osann9 mutants showed sensitivity to drought. In addition, the overexpression of OsANN9 increased superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities, which regulate reactive oxygen species homeostasis. Collectively, these findings indicate that OsANN9 may function as a positive regulator in response to drought stress by modulating antioxidant accumulation. Interestingly, the setting rates of osann9 mutant rice plants significantly decreased in comparison to wild-type plants, suggesting that OsANN9 might be involved in other molecular mechanisms in the rice seed development stage.

Polyploid cell dynamics and death before and after PEG-treatment of a NIH/3T3 derived culture: vinblastine effects on the regulation of cell subpopulations heterogeneity

BackgroundNeoplastic subpopulations can include polyploid cells that can be involved in tumor evolution and recurrence. Their origin can be traced back to the tumor microenvironment or chemotherapeutic treatment, which can alter cell division or favor cell fusion, generating multinucleated cells. Their progeny, frequently genetically unstable, can result in new aggressive and more resistant to chemotherapy subpopulations. In our work, we used NIHs cells, previously derived from the NIH/3T3 line after serum deprivation, that induced a polyploidization increase with the appearance of cells with DNA content ranging from 4 to 24c. This study aimed to analyze the cellular dynamics of NIHs culture subpopulations before and after treatment with the fusogenic agent polyethylene glycol (PEG), which allowed us to obtain new giant polyploid cells. Successively, PEG-untreated and PEG-treated cultures were incubated with the antimicrotubular poison vinblastine. The dynamics of appearance, decrease and loss of cell subpopulations were evaluated by correlating cell DNA content to mono-multinuclearity resulting from cell fusion and division process alteration and to the peculiarities of cell death events.ResultsDNA microfluorimetry and morphological techniques (phase contrast, fluorescence and TEM microscopies) indicated that PEG treatment induced a 4–24c cell increase and the appearance of new giant elements (64–140c DNA content). Ultrastructural analysis and autophagosomal–lysosomal compartment fluorochromization, which allowed us to correlate cytoplasmic changes to death events, indicated that cell depletion occurred through distinct mechanisms: apoptotic death involved 2c, 4c and 8c cells, while autophagic-like death involved intermediate 12–24c cells, showing nuclear (lobulation/micronucleation) and autophagic cytoplasm alterations. Death, spontaneously occurring, especially in intermediate-sized cells, was increased after vinblastine treatment. No evident cell loss by death events was detected in the 64–140c range.ConclusionsPEG-treated NIHs cultures can represent a model of heterogeneous subpopulations originating from cell fusion and division process anomalies. Altogether, our results suggest that the different cell dynamics of NIHs subpopulations can affect the variability of responses to stimuli able to induce cell degeneration and death. Apoptptic, autophagic or hybrid forms of cell death can also depend on the DNA content and ability to progress through the cell cycle, which may influence the persistence and fate of polyploid cell descendants, also concerning chemotherapeutic agent action.

Exogenous Salicylic Acid Alleviates Water Deficit Stress by Protecting Photosynthetic System in Maize Seedlings

Water deficit is a significant abiotic stress affecting crop growth and production. While many studies have indicated that salicylic acid (SA) plays a crucial role in mitigating the detrimental effects of environmental stress on plants, its mechanism regulating the photosynthetic adaptability of maize seedlings under water deficit is still unclear. This study aimed to investigate the impact of exogenous SA on maize seedling performance under polyethylene glycol (PEG)-induced water deficit. The results showed that PEG treatment destroyed the integrity of chloroplast and reduced chlorophyll content and photosynthesis rate (Pn), leading to growth retardation of maize seedlings with lower biomass accumulation and leaf relative water content (RWC). Moreover, chlorophyll fluorescence index, including potential photochemical activity (Fv/Fo), maximum Photosystem II (PSII) quantum yield (Fv/Fm), and energy captured by PSII reaction center for electron transfer (Eto/RC), were decreased, but energy dissipated by unit reaction center (DIo/RC) was enhanced in maize seedlings under water deficit. In addition, PEG treatment also significantly declined the activity of Rubisco and Rubisco activase (RCA) in maize seedlings. In contrast, SA treatment enhanced the content of chlorophyll, as well as the transcription level of psbA, and RCA and Rubisco small subunit (rbcS) reduced the damaging effects of PEG treatment by protecting the integrity of chloroplast and repairing the damaged PSII reaction center, thus positively regulating photosynthetic reaction and water-deficit tolerance in maize seedlings. Our data implied that SA played an important regulatory role in plant resistance to water-deficit stress, and the result will further supply the regulatory network of SA-mediated photosynthetic adaptability.