Barley Seedlings Research Articles

Paenibacillus oenotherae W2-3 degraded Welan gum to produce growth-promoting oligosaccharides.

Based on the biodegradation of Welan gum, this paper studies the properties of Welan gum degrading enzymes, degradation rules, and the application of Welan gum oligosaccharides. In order to study the biodegradation of Welan gum, a strain W2-3 capable of degrading Welan gum, was isolated from soil and identified as Paenibacillus sp. The properties of Welan gum degrading enzymes, degradation rules, and the application of Welan gum oligosaccharides were studied. After degradation, the average molecular weight of Welan gum oligosaccharides could be degraded to 500Da, and the molecular weight distribution range was wide. Through the hydroponic culture of barley seedlings, it was proved that the degradation products of Welan gum had a positive effect on plant growth. The results showed that Welan gum oligosaccharides could significantly increase the root length, plant height, and fresh weight of barley, and could be used as a growth regulator in agricultural production.

Stress-Inducible Expression of HvABF2 Transcription Factor Improves Water Deficit Tolerance in Transgenic Barley Plants.

Barley (Hordeum vulgare L.), a major cereal crop grown in arid and semi-arid regions, faces significant yield variability due to drought and heat stresses. In this study, the HvABF2 gene, encoding an ABA-dependent transcription factor, was cloned using specific primers from water deficit-stressed barley seedlings. Gene expression analysis revealed high HvABF2 expression in developing caryopses and inflorescences, with significant induction under stress conditions. The HvABF2 coding sequence was utilized to generate transgenic barley plants with both stress-inducible and constitutive expression, driven by the rice SNAC1 and maize Ubiquitin promoters, respectively. Selected transgenic barley lines, along with control lines, were subjected to water deficit-stress experiments at seedling and flag leaf stages under controlled and greenhouse conditions. The transgenic lines exhibited higher relative water content and stomatal resistance under stress compared to control plants. However, constitutive overexpression of HvABF2 led to growth retardation under well-watered conditions, resulting in reduced plant height, grain weight, and grain number. In contrast, stress-inducible expression mitigated these effects, demonstrating improved drought tolerance without adverse growth impacts. This study highlights that the stress-inducible expression of HvABF2, using the SNAC1 promoter, effectively improves drought tolerance while avoiding the negative pleiotropic effects observed with constitutive expression.

Impact nano- and micro- form of CdO on barley growth and oxidative stress response

The objective was investigated the effects of CdO and nano-CdO as potential toxic pollutants on growth and redox response of barley. CdO and nano-CdO have been found to cause significant phytotoxicity in barley seedlings, with nano-CdO increasing plant tissue cadmium accumulation. This accumulation is linked to growth retardation and oxidative stress. Low molecular weight antioxidants like restored glutathione and ascorbate have been found to increase the activity of glutathione peroxidase (GPX), glutathione-S-transferase (GSTs), and ascorbate peroxidase (APX) in green tissues. Catalase (CAT) activity increased from 50 % with 100 mg/l CdO to 70 % with 1000 mg/l and nano-CdO. The observed disturbance in redox balance signals the upregulation of corresponding genes. Antioxidant enzyme isoform gene transcripts increased for SODB, CAT2, and APX. Cadmium buildup in root cells causes oxidative stress, leading to upregulation of SOD, CAT, GR, and GSTs isoform genes as well as protein carbonylation, sulfhydryl group degradation, and MDA accumulation. CdO and nano-CdO have similar phytotoxic effects, but bioavailability affects biochemical and molecular responses.

Resistance of barley cultivars and accessions to pathotypes of the spot blotch causative agent

Background. The spot blotch disease caused by the hemibiotrophic fungus Bipolaris sorokiniana has become a serious problem for barley. Utilization of resistant or tolerant barley cultivars ensures sustainable diversity conservation and environmentfriendly crop production. Thus, supplying barley breeders with sources of resistance to harmful diseases is an urgent task. Materials and methods. A set of 100 barley accessions, earlier selected for different levels of resistance to B. sorokiniana, served as the material for this study. Eleven isolates of B. sorokiniana of various geographic origin, belonging to 4 pathotypes, were used for testing. The resistance of barley seedlings was assessed under controlled laboratory conditions, and that of adult plants under artificial infection pressure in the field. Responses to B. sorokiniana were scored using the 0–9 rating scale.Results and conclusions. Barley genotypes with race-specific resistance to the spot blotch causative agent were identified. The percentage of barley genotypes resistant to five isolates of B. sorokiniana pathotype 1 averaged 24.2%; two isolates of pathotype 3, 29.5%; three isolates of pathotype 7, 18.3%; and one isolate of pathotype 0, 37%. Barley accessions manifesting resistance in their seedlings, but susceptible in the phase of milk-wax ripeness, and vice versa, with seedling susceptibility and adult resistance, were identified. Six (6) barley genotypes showed seedling and adult resistance to pathotype 1, nine (9) to pathotype 3, and two (2) to pathotype 7. No barley accessions resistant to all isolates of the pathogen were found.

Manganese enhances cadmium tolerance in barley through mediating chloroplast integrity, antioxidant system, and HvNRAMP expression

Cadmium (Cd) is a toxic heavy metal that poses risks to crop production and food safety worldwide. This study evaluated whether manganese (Mn) addition could mitigate Cd toxicity and reduce Cd accumulation in barley seedlings. Hydroponically grown seedlings of Cd-tolerant (WSBZ) and Cd-sensitive (Dong17) barley cultivars were treated with 0.1 μM and 1 μM Cd as well as 0.2 mM Mn alone and in a combination with 0.1 or 1.0 μM Cd for 21 days. Cd exposure caused the dramatic alteration of growth and physiological parameters by disrupting chloroplast, and increased Cd accumulation in both genotypes. However, Mn addition markedly alleviated the negative impacts of all examined parameters caused by Cd stress. Cd addition enhanced expression of anti-oxidative enzyme related genes, including HvSOD, HvCAT, HvAPX, HvPOD in the two barley genotypes exposed to Cd stress. The expression analysis showed nearly all HvNRAMPs genes are dramatically up regulated by both Mn and Cd, with WSBZ having higher expression than Dong 17. Notably, HvNRAMP1 showed the highest expression due to Mn addition, highlighting its crucial role in Mn uptake and transportation in barley. Moreover, Cd stress and Mn addition increased and suppressed the expression of HvYSL5, HvHMA2 and HvHMA3, respectively. Conversely, the expression of HvYSL2, HvIRT1 and HvMTP8 was upregulated by both Mn and Cd treatments, with a further increase observed in the combined Cd and Mn treatments. It may be concluded that sufficient Mn supply is quite important for reducing Cd uptake and accumulation in plants.

Evaluation of barley genotypes for drought adaptability: based on stress indices and comprehensive evaluation as criteria.

The prevalence of drought events worldwide emphasizes the importance of screening and cultivating drought-adapted crops. In this study, 206 germplasm resources were used as materials, dry weight as target trait, and two genotyping methods as criteria to evaluate drought adaptability at the seedling establishment stage. The results showed a significant decrease in average dry weight of the tested germplasm resources (from 746.90 mg to 285.40 mg) and rich variation in the responses of dry weight among each genotype to drought (CV=61.14%). In traditional evaluation method, drought resistance coefficient (DC), geometric mean productivity index (GMP), mean productivity index (MP), stress susceptibility index (SSI), stress tolerance index (STI), and tolerance index (TOL) also exhibited diversity in tested genotypes (CV>30%). However, these indices showed varying degrees of explanation for dry weight under stress and non-stress environments and failed to differentiate drought adaptability among genotypes clearly. In new evaluation method, four stress indices were developed to quantify barley seedling production and stability capacities. Compared to traditional stress indices, the stress production index (SI) explained dry weight more comprehensively under stress conditions (R2 = 0.98), while the ideal production index (II) explained dry weight better under non-stress conditions (R2 = 0.89). Furthermore, the potential index (PI) and elasticity index (EI) eliminated disparities in traditional stress indices and comprehensively clarified the contribution of elasticity and potential to production capacity under drought stress. Ultimately, through grading evaluation and cluster analysis, the tested germplasm resources were effectively categorized, and 11 genotypes were identified as suitable for cultivation in arid areas. Overall, the comprehensive evaluation method based on the newly developed stress indices surpasses the traditional method in screening drought adaptability of crops and serves as a vital tool for identifying high-stability and high-production capacities genotypes in various environments, which is expected to provide practical guidance for barley planting and breeding in arid areas.

Pulsed high power microwave seeds priming modulates germination, growth, redox homeostasis, and hormonal shifts in barley for improved seedling growth: Unleashing the molecular dynamics

Increasing the seed germination potential and seedling growth rates play a pivotal role in increasing overall crop productivity. Seed germination and early vegetative (seedling) growth are critical developmental stages in plants. High-power microwave (HPM) technology has facilitated both the emergence of novel applications and improvements to existing in agriculture. The implications of pulsed HPM on agriculture remain unexplored. In this study, we have investigated the effects of pulsed HPM exposure on barley germination and seedling growth, elucidating the plausible underlying mechanisms. Barley seeds underwent direct HPM irradiation, with 60 pulses by 2.04 mJ/pulse, across three distinct irradiation settings: dry, submerged in deionized (DI) water, and submerged in DI water one day before exposure. Seed germination significantly increased in all HPM-treated groups, where the HPM-dry group exhibited a notable increase, with a 2.48-fold rise at day 2 and a 1.9-fold increment at day 3. Similarly, all HPM-treated groups displayed significant enhancements in water uptake, and seedling growth (weight and length), as well as elevated levels of chlorophyll, carotenoids, and total soluble protein content. The obtained results indicate that when comparing three irradiation setting, HPM-dry showed the most promising effects. Condition HPM seed treatment increases the level of reactive species within the barley seedlings, thereby modulating plant biochemistry, physiology, and different cellular signaling cascades via induced enzymatic activities. Notably, the markers associated with plant growth are upregulated and growth inhibitory markers are downregulated post-HPM exposure. Under optimal HPM-dry treatment, auxin (IAA) levels increased threefold, while ABA levels decreased by up to 65 %. These molecular findings illuminate the intricate regulatory mechanisms governing phenotypic changes in barley seedlings subjected to HPM treatment. The results of this study might play a key role to understand molecular mechanisms after pulsed-HPM irradiation of seeds, contributing significantly to address the global need of sustainable crop yield.

Biochar: A Surrogate Approach to Modulating Soil Chemical Properties and Germination Parameters of Barley Seedlings Grown in saline-calcareous soil

Biochar: A Surrogate Approach to Modulating Soil Chemical Properties and Germination Parameters of Barley Seedlings Grown in saline-calcareous soil

Methyl Jasmonate and Zinc Sulfate Induce Secondary Metabolism and Phenolic Acid Biosynthesis in Barley Seedlings.

This study aimed to reveal the impact of MeJA and ZnSO4 treatments on the physiological metabolism of barley seedlings and the content of phenolic acid. The results showed that MeJA (100 μM) and ZnSO4 (4 mM) treatments effectively increased the phenolic acid content by increasing the activities of phenylalanine ammonia-lyase and cinnamate-4-hydroxylase (PAL) and cinnamic acid 4-hydroxylase (C4H) and by up-regulating the expression of genes involved in phenolic acid synthesis. As a result of the MeJA or ZnSO4 treatment, the phenolic acid content increased by 35.3% and 30.9% at four days and by 33.8% and 34.5% at six days, respectively, compared to the control. Furthermore, MeJA and ZnSO4 treatments significantly increased the malondialdehyde content, causing cell membrane damage and decreasing the fresh weight and seedling length. Barley seedlings responded to MeJA- and ZnSO4-induced stress by increasing the activities of antioxidant enzymes and controlling their gene expression levels. Meanwhile, MeJA and ZnSO4 treatments significantly upregulated calcium-adenosine triphosphate, calmodulin-dependent protein kinase-related kinase, and calmodulin-dependent protein genes in barley seedlings. This suggested that Ca2+ may be the signaling molecule that promotes phenolic acid synthesis under MeJA and ZnSO4 treatment. This study deepens the understanding of the phenolic acid enrichment process in barley seedlings under MeJA and ZnSO4 treatments.

Silicon regulates phosphate deficiency through involvement of auxin and nitric oxide in barley roots.

Silicon application mitigates phosphate deficiency in barley through an interplay with auxin and nitric oxide, enhancing growth, photosynthesis, and redox balance, highlighting the potential of silicon as a fertilizer for overcoming nutritional stresses. Silicon (Si) is reported to attenuate nutritional stresses in plants, but studies on the effect of Si application to plants grown under phosphate (Pi) deficiency are still very scarce, especially in barley. Therefore, the present work was undertaken to investigate the potential role of Si in mitigating the adverse impacts of Pi deficiency in barleyHordeum vulgareL. (var. BH902). Further, the involvement of two key regulatory signaling molecules--auxin and nitric oxide (NO)--in Si-induced tolerance against Pi deficiency in barley was tested. Morphological attributes, photosynthetic parameters, oxidative stress markers (O2·-, H2O2, and MDA), antioxidant system (enzymatic--APX, CAT, SOD, GR, DHAR, MDHAR as well as non-enzymatic--AsA and GSH), NO content, and proline metabolism were the key traits that were assessed under different treatments. The P deficiency distinctly declined growth of barley seedlings, which was due to enhancement in oxidative stress leading to inhibition of photosynthesis. These results were also in parallel with an enhancement in antioxidant activity, particularly SOD and CAT, and endogenous proline level and its biosynthetic enzyme (P5CS). The addition of Si exhibited beneficial effects on barley plants grown in Pi-deficient medium as reflected in increased growth, photosynthetic activity, and redox balance through the regulation of antioxidant machinery particularly ascorbate-glutathione cycle. We noticed that auxin and NO were also found to be independently participating in Si-mediated improvement of growth and other parameters in barley roots under Pi deficiency. Data of gene expression analysis for PHOSPHATE TRANSPORTER1 (HvPHT1) indicate that Si helps in increasing Pi uptake as per the need of Pi-deficient barley seedlings, and also auxin and NO both appear to help Si in accomplishing this task probably by inducing lateral root formation. These results are suggestive of possible application of Si as a fertilizer to correct the negative effects of nutritional stresses in plants. Further research at genetic level to understand Si-induced mechanisms for mitigating Pi deficiency can be helpful in the development of new varieties with improved tolerance against Pi deficiency, especially for cultivation in areas with Pi-deficient soils.

Assessment of Phytotoxicity and Efficiency of Date Palm Waste Compost on Barley Seeds Germination and Seedlings Growth

ABSTRACT The valorization of date palm wastes as bioresources has received little attention. In this context, the feasibility of date palm waste valorization through composting and the application effects on barley plants production under control condition was investigated. The principal requirements for compost to be safely used are stability and maturity that refer, respectively, to the microbial biomass activity’s level, germination tests, and plant growth bioassays or phytotoxicity. Indeed, the phytotoxicity of composted date palm waste used for seed germination and seedling growth bioassays was researched. The finished compost values of the C/N ratio were 15.36 and 18.58%, 1.21%, 0.54%, and 0.95% for total organic carbon, N, P, and K contents, respectively. The concentration of heavy metals and microelements were lower and met the requirement established by national standards. Moreover, the end product was free from harmful pathogens like Salmonella, Escherichia coli, total coliforms, and fecal coliform bacteria. Application of compost extract (especially 25%, 50%, and 75%) did not affect barley seed germination, stimulated hypocotyl and radicle growth and is characterized by a GI exceeding 90%, demonstrating its stability and lack of phytotoxic effect. Moreover, compost promotes plant growth, improved physiological parameters, photosynthetic pigments, and plant biomass. According to the results, the prepared compost especially at the dose T3 (soil amended with 30 t/ha) increased the nutrients availability and uptake which may be the reason for an increase in photosynthetic activity, chlorophyll synthesis, and dry matter accumulation. Composting may well represent an acceptable solution for disposing of date palm waste and be of great interest to sustainable agriculture in Tunisia oasis ecosystems.

Cadmium toxicity promotes hormonal imbalance and induces the expression of genes involved in systemic resistances in barley.

Cadmium (Cd) is a widely distributed pollutant that adversely affects plants' metabolism and productivity. Phytohormones play a vital role in the acclimation of plants to metal stress. On the other hand, phytohormones trigger systemic resistances, including systemic acquired resistance (SAR) and induced systemic resistance (ISR), in plants in response to biotic interactions. The present study aimed to investigate the possible induction of SAR and ISR pathways in relation to the hormonal alteration of barley seedlings in response to Cd stress. Barley seedlings were exposed to 1.5mgg-1 Cd in the soil for three days. The nutrient content, oxidative status, phytohormones profile, and expression of genes involved in SAR and ISR pathways of barley seedlings were examined. Cd accumulation resulted in a reduction in the nutrient content of barley seedlings. The specific activity of superoxide dismutase and the hydrogen peroxide content significantly increased in response to Cd toxicity. Abscisic acid, jasmonic acid, and ethylene content increased under Cd exposure. Cd treatment resulted in the upregulation of NPR1, PR3, and PR13 genes in SAR pathways. The transcripts of PAL1 and LOX2.2 genes in the ISR pathway were also significantly increased in response to Cd treatment. These findings suggest that hormonal-activated systemic resistances are involved in the response of barley to Cd stress.

Applications of humic and fulvic acid under saline soil conditions to improve growth and yield in barley.

Enriching the soil with organic matter such as humic and fulvic acid to increase its content available nutrients, improves the chemical properties of the soil and increases plant growth as well as grain yield. In this study, we conducted a field experiment using humic acid (HA), fulvic acid (FA) and recommended dose (RDP) of phosphorus fertilizer to treat Hordeum vulgare seedling, in which four concentrations from HA, FA and RDP (0.0 %, 50 %, 75 % and 100%) under saline soil conditions . Moreover, some agronomic traits (e.g. grain yield, straw yield, spikes weight, plant height, spike length and spike weight) in barley seedling after treated with different concentrations from HA, FA and RDP were determined. As such the beneficial effects of these combinations to improve plant growth, N, P, and K uptake, grain yield, and its components under salinity stress were assessed. The findings showed that the treatments HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6), improved number of spikes/plant, 1000-grain weight, grain yield/ha, harvest index, the amount of uptake of nitrogen (N), phosphorous (P) and potassium (K) in straw and grain. The increase for grain yield over the control was 64.69, 56.77, 49.83, 49.17, and 44.22% in the first season, and 64.08, 56.63, 49.19, 48.87, and 43.69% in the second season,. Meanwhile, the increase for grain yield when compared to the recommended dose was 22.30, 16.42, 11.27, 10.78, and 7.11% in the first season, and 22.17, 16.63, 11.08, 10.84, and 6.99% in the second season. Therefore, under salinity conditions the best results were obtained when, in addition to phosphate fertilizer, the soil was treated with humic acid or foliar application the plants with fulvic acid under one of the following treatments: HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6). The result of the use of organic amendments was an increase in the tolerance of barley plant to salinity stress, which was evident from the improvement in the different traits that occurred after the treatment using treatments that included organic amendments (humic acid or fulvic acid).

The influence of mitochondria-targeted antioxidants, plastoquinone derivatives on the resistance of grain crops to water deficiency

The article presents the results of a study of the influence of plastoquinone derivatives: 10-(6'-plastoquinonyl)decyltriphenylphosphonium (SkQ1) and 10-(6′-methylplastoquinonyl) decyltriphenylphosphonium (SkQ3) on the resistance of grain crops to soil moisture deficiency. The object of the study were seedlings of spring barley (Hordeum vulgare L.) cultivar “Sokol” and winter wheat (Triticum aestivum L.) cultivar “Kalym”. The growth rates of plants were studied for 14 days under normal conditions and with a lack of moisture, pre-treated with 2.5 nm solutions of SkQ1 and SkQ3. It has been shown that treating seeds with solutions of SkQ1 and SkQ3 increases the growth rate of the studied crops under conditions of lack of moisture compared to the control. Also, in the roots and leaves of 14-day-old barley seedlings, an analysis of the transcriptional activity of the genes SodA1, SodB, GR, GST1, GST6, Cat1, Cat2, Apx1, encoding oxidative stress proteins, was carried out. It was shown that a decrease in soil moisture by 1.8 and 2.0 times compared to the control reduces to varying degrees the weight of roots and leaves in 14-day-old barley seedlings and increases the transcriptional activity of all studied genes in both leaves and roots. Treatment of seeds with solutions of SkQ1 and SkQ3 under conditions of moisture deficiency increases the dry weight of barley roots and leaves and reduces the transcriptional activity of the studied genes in the roots. Keywords: PLASTOQUINONE DERIVATIVES, SkQ1, SkQ3, MITOCHONDRIA-TARGETED ANTIOXIDANTS, ROS, SOIL MOISTURE DEFICIENCY, STABILITY, TRANSCRIPTIONAL GENE ACTIVITY

Ramularia leaf spot management alternatives in barley optimizing the use of fungicides for its control: Doctoral thesis abstract

Ramularia collo-cygni (Rcc) is the causal agent of Ramularia leaf spot (RLS). The main management tool is the use of foliar fungicides, the impact of which on cereal safety is unknown. Therefore, the aim of this thesis was to optimise the management of ramulariosis in barley and to minimise fungicide residues in grain. The specific objectives were: (i) to validate a method for the detection and quantification of Rcc in seeds and seedlings by real-time PCR (qPCR), (ii) to determine the importance of seeds as a source of in-crop Rcc inoculum in production systems in Uruguay, (iii) to develop a methodology to determine the fungicides proposed for the control of rhamulariosis in barley grain, and (iv) to identify foliar fungicide application strategies to minimise rhamulariosis and ensure fungicide safety in the grain produced. The qPCR technique was validated for the detection and quantification of Rcc in barley seeds and seedlings. This qPCR technique will allow the optimal timing of foliar fungicide applications to be determined by detecting Rcc in seedlings. The amount of Rcc DNA in commercial lots varied within and between growing seasons, highlighting the importance of this tool for quantifying fungal load prior to sowing. A method was developed to quantify fungicide residues in barley grain. This method was extended to quantify fungicides in wheat grain and mycotoxins produced by the Fusarium species. This analytical methodology could be useful for monitoring compliance with maximum residue limits (MRLs) in winter cereal production. Foliar fungicide strategies for the control of RLS were evaluated in five trials over three consecutive years. The efficacy of fungicides in controlling the disease and ensuring grain safety was tested with fungicide residue levels below MRLs. The results contribute to the management of RLS with tools to reduce fungicide use and ensure barley grain safety.

Understanding the influence of applying plant extracts and microorganism culture filtrates against barley leaf rust disease

Rust fungi are devastating plant pathogens, and several Puccinia species have exerting substantial financial impacts on global barley cultivation. Fungicides are used on a large scale as an effective method for combating phytopathogenic fungi. The negative environmental impacts of fungicides are steadily escalating on a daily basis. Consequently, researchers are currently exploring alternative approaches to mitigate the use of fungicides, such as the utilization of plant extracts. This method has proven effective due to its incorporation of natural antifungal substances. Among the nine natural elicitors that were tested, the application of plant extracts on barley seedlings resulted in an increase in the incubation and latent periods of Puccinia hordei. These periods are integral components of partial and induced resistance, effectively mitigating the incidence of barley leaf rust disease by over 70% on mature plants. Similarly, the biochemical analyses demonstrated a notable augmentation in all the tested treatments’ overall phenolics and oxidative enzyme activities (peroxidase and polyphenol oxidase). Random amplified polymorphic DNA (SCoT) test serves as a viable approach for assessing the impact of plant extracts and microorganisms on barley plants. The results obtained from this study indicate that the detection of DNA polymorphism through SCoT analysis holds a significant potential powerful tool to evaluate genetic changes compared with untreated plants although some of them tested displayed high similarities at the morphological reaction.

Effects of acetic acid treatment on growth and pigment contents in barley

Acetic acid (AA) is an organic acid and has been widely used as food preservative and a dietary spice in vinegar form. In addition to its therapeutic uses in its vinegar form, AA attenuates inhibitory effects of stress in plants. However, in some plant species toxic effects of AA have been found. Therefore, in this study, 0, 2.5 and 5 mM concentrations of AA were applied to 2-day-old barley (Hordeum vulgare L. cv. Bornova-92) seedlings for 2 days in order to investigate the possible toxic effects of AA. After treatments, seedlings were grown in AA-free conditions for 2 days to recover. AA inhibited root and shoot growth; decreased water content, fresh weight, chlorophyll, pheophytin, and carotenoid contents. However, anthocyanin and flavonoid contents, as well as the levels of UV-absorbing compounds and UV-B marker increased in the leaves of AA-treated plants. AA increased hydrogen peroxide (H2O2) content in shoots and induced cell death in roots. Soluble carbohydrate content decreased in roots of AA-treated plants while insoluble carbohydrate content increased. Our results demonstrate that AA in young barley seedlings can exhibit its toxic effects through oxidative stress, which induced antioxidative response in the form of molecules with antioxidative activities. These effects persisted for 2 days after the removal of AA.

GABA Metabolism and MDA Production in Barley (Hordeum vulgare L.) Seedlings under Salinity and Osmotic Stresses

Aim This study examined the gamma-aminobutyric acid (GABA) shunt pathway in response to salt and osmotic stresses in three barley (Hordeum vulgare L.) genotypes (Acsad176, Athroh, and Rum) in terms of seed germination, seedlings growth, oxidative damage through malondialdehyde (MDA) accumulation as an indicator for reactive oxygen species (ROS), GABA metabolite accumulation, chlorophyll level, total proteins, total carbohydrates and the expression of glutamate decarboxylase gene (GAD) analysis. Background GABA is a secondary metabolite that modulates nitrogen metabolism, protects against oxidative damage, and cytosolic pH in response to various abiotic and biotic stress in plants. Methods The effects of salt and osmotic stresses imposed by different concentrations of mannitol, sorbitol, and NaCl on the three barley genotypes were studied. Seed germination, seedling length, fresh weight, and dry mass were recorded. The physiological and biochemical responses as per GABA and MDA accumulation, total chlorophyll, proteins and carbohydrates, and the level of GAD expression were also characterized and determined. Results Mannitol, sorbitol, and NaCl treatments decreased seed germination and seedling growth for the three barely genotypes used in this study. MDA concentration was increased in seedlings of all genotypes with increasing NaCl, mannitol, and sorbitol concentrations. Acsad 176 showed high GABA accumulation under NaCl treatment. Mannitol treatment significantly increased GABA accumulation in the Rum genotype. All salt and osmotic treatments decreased chlorophyll a and b and carbohydrate content and significantly increased GAD transcription in all barley genotypes. Salt and osmotic stresses affected the total protein content in all genotypes. Conclusion Acsad 176 genotype may adapt to NaCl stress by accumulating carbohydrates more than Athroh and Rum. GABA shunt is a crucial signaling and metabolic pathway facilitating barley's adaptation to salt and osmotic stress. In soil with high salt and osmotic contents, the Acsad 176 genotype is the recommended genotype for cultivation.

Toxic effect of elements on the germination and initial development of barley seeds (Hordeum vulgare L.)

Barley (Hordeum vulgare) is an agricultural vegetable from the Poaceae family used in food and beer production. The study aimed to evaluate the toxic effect of Aluminum (Al) and Copper (Cu) on germination and initial development in barley seeds cultivar KWS Irina. Different concentrations (0, 35, 85 and 125 mg L-1) of aqueous solution of Al and Cu were produced from their chlorides. The toxicity experiment was carried out in a germination box maintained in a germination chamber with a 12-h photoperiod. After 15 days of germination, the seedlings were measured using a millimetric ruler (cm) where they were evaluated for plant length, root length, and fresh and dry mass of plant and root determined on a digital analytical scale (g). Barley seedlings cultivar KWS Irina demonstrated to be intolerant to concentrations of the toxic elements Al and Cu in all plant parameters analyzed, except for plant dry mass. Future studies should be carried out comparing the initial and reproductive development of this barley cultivar in terms of the presence and absence of toxic elements.

Isolation and identification of a new Bacillus glycinifermentans strain from date palm rhizosphere and its effect on barley seeds under heavy metal stress.

Soil contamination by heavy metals is one of the major problems that adversely decrease plant growth and biomass production. Inoculation with the plant growth-promoting rhizobacteria (PGPR) can attenuate the toxicity of heavy metals and enhancing the plant growth. In this study, we evaluated the potential of a novel extremotolerant strain (IS-2T) isolated from date palm rhizosphere to improve barley seedling growth under heavy metal stress. The species-level identification was carried out using morphological and biochemical methods combined with whole genome sequencing. The bacterial strain was then used in vitro for inoculating Hordeum vulgare L. exposed to three different Cr, Zn, and Ni concentrations (0.5, 1, and 2mM) in petri dishes and different morphological parameters were assessed. The strain was identified as Bacillus glycinifermentans species. This strain showed high tolerance to pH (6-11), salt stress (0.2-2M), and heavy metals. Indeed, the minimum inhibitory concentrations at which bacterium was unable to grow were 4mM for nickel, 3mM for zinc, more than 8mM for copper, and 40mM for chromium, respectively. It was observed that inoculation of Hordeum vulgare L. under metal stress conditions with Bacillus glycinifermentans IS-2T stain improved considerably the growth parameters. The capacity of the IS-2T strain to withstand a range of abiotic stresses and improve barley seedling development under lab conditions makes it a promising candidate for use as a PGPR in zinc, nickel, copper, and chromium bioremediation.