Genome-wide association scan reveals the reinforcing effect of nano-potassium in improving the yield and quality of salt-stressed barley via enhancing the antioxidant defense system.

Salinity is one of the major environmental factor that can greatly impact the growth, development, and productivity of barley. Our study aims to detect the natural phenotypic variation of morphological and physiological traits under both salinity and potassium nanoparticles (n-K) treatment. In addition to understanding the genetic basis of salt tolerance in barley is a critical aspect of plant breeding for stress resilience. Therefore, a foliar application of n-K was applied at the vegetative stage for 138 barley accessions to enhance salt stress resilience. Interestingly, barley accessions showed high significant increment under n-K treatment compared to saline soil. Based on genome-wide association studies (GWAS) analysis, causative alleles /reliable genomic regions were discovered underlying improved salt resilience through the application of potassium nanoparticles. On chromosome 2H, a highly significant QTN marker (A:C) was located at position 36,665,559 bp which is associated with APX, AsA, GSH, GS, WGS, and TKW under n-K treatment. Inside this region, our candidate gene is HORVU.MOREX.r3.2HG0111480 that annotated as NAC domain protein. Allelic variation detected that the accessions carrying C allele showed higher antioxidants (APX, AsA, and GSH) and barley yield traits (GS, WGS, and TKW) than the accessions carrying A allele, suggesting a positive selection of the accessions carrying C allele that could be used to develop barley varieties with improved salt stress resilience.

Elucidating the genetic architecture controlling antioxidant status and ionic balance in barley under salt stress.

KEY MESSAGE: Association genetic analysis empowered us to identify candidate genes underlying natural variation of morpho-physiological, antioxidants, and grain yield-related traits in barley. Novel intriguing genomic regions were identified and dissected. Salinity stress is one of the abiotic stresses that influence the morpho-physiological, antioxidants, and yield-related traits in crop plants. The plants of a core set of 138 diverse barley accessions were analyzed after exposure to salt stress under field conditions during the reproductive phase. A genome-wide association scan (GWAS) was then conducted using 19,276 single nucleotide polymorphisms (SNPs) to uncover the genetic basis of morpho-physiological and grain-related traits. A wide range of responses to salt stress by the accessions was explored in the current study. GWAS detected 263 significantly associated SNPs with the antioxidants, K+/Na+ content ratio, and agronomic traits. Five genomic regions harbored interesting putative candidate genes within LD ± 1.2 Mbp. Choromosome 2H harbored many candidate genes associated with the antioxidants ascorbic acid (AsA) and glutathione (GSH), such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR), under salt stress. Markedly, an A:C SNP at 153,773,211 bp on chromosome 7H is located inside the gene HORVU.MOREX.r3.7HG0676830 (153,772,300-153,774,057 bp) that was annotated as L-gulonolactone oxidase, regulating the natural variation of SOD_S and APX_S. The allelic variation at this SNP reveals a negative selection of accessions carrying the C allele, predominantly found in six-rowed spring landraces originating from Far-, Near-East, and central Asia carrying photoperiod sensitive alleles having lower activity of enzymatic antioxidants. The SNP-trait associations detected in the current study constitute a benchmark for developing molecular selection tools for antioxidant compound selection in barley.

Oil sands operations as a large source of secondary organic aerosols.

Worldwide heavy oil and bitumen deposits amount to 9 trillion barrels of oil distributed in over 280 basins around the world, with Canada home to oil sands deposits of 1.7 trillion barrels. The global development of this resource and the increase in oil production from oil sands has caused environmental concerns over the presence of toxic compounds in nearby ecosystems and acid deposition. The contribution of oil sands exploration to secondary organic aerosol formation, an important component of atmospheric particulate matter that affects air quality and climate, remains poorly understood. Here we use data from airborne measurements over the Canadian oil sands, laboratory experiments and a box-model study to provide a quantitative assessment of the magnitude of secondary organic aerosol production from oil sands emissions. We find that the evaporation and atmospheric oxidation of low-volatility organic vapours from the mined oil sands material is directly responsible for the majority of the observed secondary organic aerosol mass. The resultant production rates of 45-84 tonnes per day make the oil sands one of the largest sources of anthropogenic secondary organic aerosols in North America. Heavy oil and bitumen account for over ten per cent of global oil production today, and this figure continues to grow. Our findings suggest that the production of the more viscous crude oils could be a large source of secondary organic aerosols in many production and refining regions worldwide, and that such production should be considered when assessing the environmental impacts of current and planned bitumen and heavy oil extraction projects globally.

Acute and chronic metabolic effects of carvedilol in high-fructose, high-fat diet-fed mice: implication of ß-arrestin2 pathway.

We aimed to investigate the acute and chronic effects of carvedilol on insulin resistance in high-fructose, high-fat diet (HFrHFD) - fed mice and the implication of the ß-arrestin2 pathway. The acute effect of carvedilol (10 mg/kg, i.p.) on glucose tolerance and hepatic lipid signaling in normal and insulin resistant mice was investigated. Then, the chronic effect of carvedilol on insulin resistance and dyslipidemia in HFrHFD-fed mice was examined. Changes in ß-arrestin2 and its downstream signals in liver, skeletal muscle, and adipose tissue were measured. This involved measuring phosphatidylinositol 4,5-bisphosphate (PIP2) and diacylglycerol (DAG) levels and protein kinase B (AKT) activity. Carvedilol acutely reduced fasting blood glucose levels in both normal and insulin resistant mice without significantly affecting the glucose tolerance. These acute effects were associated with increased hepatic PIP2 but decreased hepatic DAG levels. Chronic administration of carvedilol significantly ameliorated insulin resistance and dyslipidemia in HFrHFD-fed mice. These chronic effects were associated with increased ß-arrestin2, PIP2, and AKT activity levels but decreased DAG levels in the classical insulin target tissues. In conclusion, carvedilol acutely maintains glucose homeostasis and chronically ameliorates insulin resistance and dyslipidemia in HFrHFD-fed mice. The insulin sensitizing effects of carvedilol are highly correlated with the upregulation of ß-arrestin2 pathway.

Evolution of Atmospheric Total Organic Carbon from Petrochemical Mixtures.

Reactive organic compounds play a central role in the formation of ozone and secondary organic aerosols. The ability to accurately predict their fate, in part, relies upon quantitative knowledge of the chemical and physical parameters associated with the total organic carbon (TOC), which includes both precursors and oxidation products that evolve in the atmosphere over short to long time scales. However, such knowledge, obtained via limited carbon closure experiments, has not been attained for complex anthropogenic emissions. Here we present the first comprehensive characterization of TOC in the atmospheric oxidation of organic vapors from light and heavy oil mixtures associated with oil sand operations. Despite the complexity of the investigated oil mixtures, we are able to achieve carbon closure (83-116%) within the uncertainties (±20%), with the degree of the closure being dependent upon the vapor composition and NOx levels. In contrast to biogenic precursors (e.g., α-pinene), the photochemical time scale required for a largely complete oxidation and evolution of chemical parameters is very long for the petrochemical vapors (i.e., ∼7-10 days vs ∼1 day), likely due to the lower initial precursor reactivity. This suggests that petrochemical emissions and their impacts are likely to extend further spatially than biogenic emissions, and retain more of their complex composition and reactivity for many days. The results of this work provide key parameters to regional models for further improving the representation of the chemical evolution of petrochemical emissions.

Fugitive Emissions of Volatile Organic Compounds from a Tailings Pond in the Oil Sands Region of Alberta.

Tailings ponds in the oil sands (OS) region in Alberta, Canada, have been associated with fugitive emissions of volatile organic compounds (VOCs) and other pollutants to the atmosphere. However, the contribution of tailings ponds to the total fugitive emissions of VOCs from OS operations remains uncertain. To address this knowledge gap, a field study was conducted in the summer of 2017 at Suncor's Pond 2/3 to estimate emissions of a suite of pollutants including 68 VOCs using a combination of micrometeorological methods and measurements from a flux tower. The results indicate that in 2017, Pond 2/3 was an emission source of 3322 ± 727 tons of VOCs including alkanes, aromatics, and oxygenated and sulfur-containing organics. While the total VOC emissions were approximately a factor of 2 higher than those reported by Suncor, the individual VOC species emissions varied by up to a factor of 12. A chemical mass balance (CMB) receptor model was used to estimate the contribution of the tailings pond to VOC pollution events in a nearby First Nations and Metis community in Fort McKay. CMB results indicate that Suncor Pond 2/3 contributed up to 57% to the total mass of VOCs measured at Fort McKay, reinforcing the importance of accurate VOC emission estimation methods for tailings ponds.

Differences between measured and reported volatile organic compound emissions from oil sands facilities in Alberta, Canada.

Large-scale oil production from oil sands deposits in Alberta, Canada has raised concerns about environmental impacts, such as the magnitude of air pollution emissions. This paper reports compound emission rates (E) for 69-89 nonbiogenic volatile organic compounds (VOCs) for each of four surface mining facilities, determined with a top-down approach using aircraft measurements in the summer of 2013. The aggregate emission rate (aE) of the nonbiogenic VOCs ranged from 50 ± 14 to 70 ± 22 t/d depending on the facility. In comparison, equivalent VOC emission rates reported to the Canadian National Pollutant Release Inventory (NPRI) using accepted estimation methods were lower than the aE values by factors of 2.0 ± 0.6, 3.1 ± 1.1, 4.5 ± 1.5, and 4.1 ± 1.6 for the four facilities, indicating underestimation in the reported VOC emissions. For 11 of the combined 93 VOC species reported by all four facilities, the reported emission rate and E were similar; but for the other 82 species, the reported emission rate was lower than E The median ratio of E to that reported for all species by a facility ranged from 4.5 to 375 depending on the facility. Moreover, between 9 and 53 VOCs, for which there are existing reporting requirements to the NPRI, were not included in the facility emission reports. The comparisons between the emission reports and measurement-based emission rates indicate that improvements to VOC emission estimation methods would enhance the accuracy and completeness of emission estimates and their applicability to environmental impact assessments of oil sands developments.

Carvedilol protects against hepatic ischemia/reperfusion injury in high-fructose/high-fat diet-fed mice: Role of G protein-coupled receptor kinase 2 and 5.

Hepatic ischemia/reperfusion injury (H-IRI) is associated with irreversible liver damage. The current study aimed to investigate the protective effect of carvedilol against H-IRI in high-fructose high-fat diet (HFrHFD)-fed mice and the role of G protein-coupled receptor kinase 2 and 5 (GRK2 and GRK5). Mice were fed HFrHFD for 16 weeks; then mice were subjected to 30 min of ischemia followed by 1 h of reperfusion at the end of feeding period. Carvedilol (20 mg/kg, i.p.) was administered 30 min before ischemia. To explore the role of GRK2 and GRK5 in mediating carvedilol effects, paroxetine (GRK2 inhibitor, 10 mg/kg, i.p.) and amlexanox (GRK5 inhibitor, 25 mg/kg, i.p.) were administered 30 min before carvedilol administration. Liver function, histopathology and hepatic oxidative stress, as well as inflammatory and apoptotic markers were measured at the end of the experiment. In addition, adrenergic receptor downstream signals were measured in the liver. Results showed increased markers of liver injury (ALT and AST) in mice subjected to H-IRI. Moreover, liver injury was associated with slight collagen deposits as revealed by histopathology and elevated hepatic levels of oxidative stress, inflammatory and apoptotic markers. On the other hand, carvedilol protected mice against H-IRI and improved all associated pathological changes. Furthermore, pre-injection of either GRK2 or GRK5 inhibitor did not change carvedilol effects on serum ALT level and liver collagen deposits, while increased its antioxidant, anti-inflammatory and anti-apoptotic effects. In conclusion, carvedilol protects against H-IRI in HFrHFD-fed mice. GRK2 and GRK5 may not play a potential role in mediating this effect.

Understanding the Impact of High-NOx Conditions on the Formation of Secondary Organic Aerosol in the Photooxidation of Oil Sand-Related Precursors.

Oil sands (OS) are an important type of heavy oil deposit, for which operations in Alberta, Canada, were recently found to be a large source of secondary organic aerosol (SOA). However, SOA formation from the OS mining, processing, and subsequent tailings, especially in the presence of NOx, remains unclear. Here, photooxidation experiments for OS-related precursors under high-NOx conditions were performed using an oxidation flow reactor, in which ∼95% of peroxy radicals (RO2) react with NO. The SOA yields under high-NOx conditions were found to be lower than yields under low-NOx conditions for all precursors, which is likely due to the higher volatilities of the products from the RO2 + NO pathway compared with RO2 + HO2. The SOA yields under high-NOx conditions show a strong dependence on pre-existing surface area (not observed in previous low-NOx experiments), again attributed to the higher product volatilities. Comparing the mass spectra of SOA formed from different precursors, we conclude that the fraction of m/z > 80 (F80) can be used as a parameter to separate different types of SOA in the region. In addition, particle-phase organic nitrate was found to be an important component (9-23%) of OS SOA formed under high-NOx conditions. These results have implications for better understanding the atmospheric processing of OS emissions.

Quantifying the Primary Emissions and Photochemical Formation of Isocyanic Acid Downwind of Oil Sands Operations.

Isocyanic acid (HNCO) is a known toxic species and yet the relative importance of primary and secondary sources to regional HNCO and population exposure remains unclear. Off-road diesel fuel combustion has previously been suggested to be an important regional source of HNCO, which implies that major industrial facilities such as the oil sands (OS), which consume large quantities of diesel fuel, can be sources of HNCO. The OS emissions of nontraditional toxic species such as HNCO have not been assessed. Here, airborne measurements of HNCO were used to estimate primary and secondary HNCO for the oil sands. Approximately 6.2 ± 1.1 kg hr-1 was emitted from off-road diesel activities within oil sands facilities, and an additional 116-186 kg hr-1 formed from the photochemical oxidation of diesel exhaust. Together, the primary and secondary HNCO from OS operations represent a significant anthropogenic HNCO source in Canada. The secondary HNCO downwind of the OS was enhanced by up to a factor of 20 relative to its primary emission, an enhancement factor significantly greater than previously estimated from laboratory studies. Incorporating HNCO emissions and formation into a regional model demonstrated that the HNCO levels in Fort McMurray (∼10-70 km downwind of the OS) are controlled by OS emissions; > 50% of the monthly mean HNCO arose from the OS. While the mean HNCO levels in Fort McMurray are predicted to be below the 1000 pptv level associated with potential negative health impacts, (∼25 pptv in August-September), an order of magnitude increase in concentration is predicted (250-600 pptv) when the town is directly impacted by OS plumes. The results here highlight the importance of obtaining at-source HNCO emission factors and advancing the understanding of secondary HNCO formation mechanisms, to assess and improve HNCO population exposure predictions.

Total organic carbon measurements reveal major gaps in petrochemical emissions reporting.

Anthropogenic organic carbon emissions reporting has been largely limited to subsets of chemically speciated volatile organic compounds. However, new aircraft-based measurements revealed total gas-phase organic carbon emissions that exceed oil sands industry-reported values by 1900% to over 6300%, the bulk of which was due to unaccounted-for intermediate-volatility and semivolatile organic compounds. Measured facility-wide emissions represented approximately 1% of extracted petroleum, resulting in total organic carbon emissions equivalent to that from all other sources across Canada combined. These real-world observations demonstrate total organic carbon measurements as a means of detecting unknown or underreported carbon emissions regardless of chemical features. Because reporting gaps may include hazardous, reactive, or secondary air pollutants, fully constraining the impact of anthropogenic emissions necessitates routine, comprehensive total organic carbon monitoring as an inherent check on mass closure.

Nitric acid-induced surface disordering on ice.

We examined the interaction of HNO3 with water ice for partial pressures 2 × 10(-8) Torr to 1 × 10(-5) Torr and at temperatures from 216 to 256 K using (i) the surface-specific technique ellipsometry and (ii) a coated wall flow tube reactor, both coupled with chemical ionization mass spectrometry detection of HNO3 in the gas phase. Our ellipsometry results show that exposure to HNO3 induces surface disordering on ice at a range of environmentally relevant temperatures and HNO3 partial pressures, particularly in the vicinity of the boundary between the ice and the HNO3·3H2O phases. The coated wall flow tube studies indicate that the nature of HNO3 uptake changes from reversible adsorption to a continuous flux of HNO3 into the bulk in the presence of a disordered interfacial layer. These results have implications for atmospheric chemistry in the upper troposphere and in polar regions.

Photochemical aging of light-absorbing secondary organic aerosol material.

Dark reactions of methylglyoxal with NH4(+) in aqueous aerosols yield light-absorbing and surface-active products that can influence the physical properties of the particles. Little is known about how the product mixture and its optical properties will change due to photolysis as well as oxidative aging by O3 and OH in the atmosphere. Here, we report the results of kinetics and product studies of the photochemical aging of aerosols formed by atomizing aqueous solutions of methylglyoxal and ammonium sulfate. Experiments were performed using aerosol flow tube reactors coupled with an aerosol chemical ionization mass spectrometer (Aerosol-CIMS) for monitoring gas- and particle-phase compositions. Particles were also impacted onto quartz windows in order to assess changes in their UV-visible absorption upon oxidation. Photooxidation of the aerosols leads to the formation of small, volatile organic acids including formic acid, acetic acid, and glyoxylic acid. The atmospheric lifetime of these species during the daytime is predicted to be on the order of minutes, with photolysis being an important mechanism of degradation. The lifetime with respect to O3 oxidation was observed to be on the order of hours. O3 oxidation also leads to a net increase in light absorption by the particles due to the formation of additional carbonyl compounds. Our results are consistent with field observations of high brown carbon absorption in the early morning.

Association mapping unravels the genetics controlling seedling drought stress tolerance in winter wheat.

Drought is a major constraint in wheat (Triticum aestivum L.) grain yield. The present work aimed to identify quantitative trait nucleotides (QTNs)/ candidate genes influencing drought tolerance-related traits at the seedling stage in 261 accessions of a diverse winter wheat panel. Seeds from three consecutive years were exposed to polyethylene glycol 12% (PEG-6000) and a control treatment (distilled water). The Farm-CPU method was used for the association analysis with 17,093 polymorphic SNPs. PEG treatment reduced shoot length (SL) (-36.3%) and root length (RL) (-11.3%) compared with control treatments, while the coleoptile length (CL) was increased by 11% under drought conditions, suggesting that it might be considered as an indicator of stress-tolerance. Interestingly, we revealed 70 stable QTN across 17 chromosomes. Eight QTNs related to more than one trait were detected on chromosomes 1B, 2A (2), 2B, 2D, 4B, 7A, and 7B and located nearby or inside candidate genes within the linkage disequilibrium (LD) interval. For instance, the QTN on chromosome 2D is located inside the gene TraesCS2D02G133900 that controls the variation of CL_S and SL_C. The allelic variation at the candidate genes showed significant influence on the associated traits, demonstrating their role in controlling the natural variation of multi-traits of drought stress tolerance. The gene expression of these candidate genes under different stress conditions validates their biological role in stress tolerance. Our findings offer insight into understanding the genetic factors and diverse mechanisms in response to water shortage conditions that are important for wheat improvement and adaptation at early developmental stages.

Exploring genetic variation among Jordanian Solanum lycopersicon L. landraces and their performance under salt stress using SSR markers.

BACKGROUND: Tomatoes (Solanum lycopersicon L.) are one of the main daily consumed vegetables in the human diet. Tomato has been classified as moderately sensitive to salinity at most stages of plant development, including seed germination, seedling (vegetative), and reproduction phases. In this study, we evaluated the performance and response of 39 tomato landraces from Jordan under salt stress conditions. Furthermore, the landraces were also genetically characterized using simple sequence repeat (SSR) markers. RESULTS: The studied morphological-related traits at the seedling stage were highly varied among landraces of which the landrace number 24 (Jo970) showed the best performance with the highest salt tolerance. The total number of amplification products produced by five primers (LEaat002, LEaat006, LEaat008, LEga003, LEta019) was 346 alleles. Primer LEta 019 produced the highest number of alleles (134) and generated the highest degree of polymorphism (100%) among landraces in addition to primers (LEaat002, LEaat006, LEaat008). The lowest dissimilarity among landraces ranged from 0.04 between accessions 25 (Jo969) and 26 (Jo981) and the highest dissimilarity (1.45) was found between accessions 39 (Jo980) and both 3 (Jo960) and 23 (Jo978). The dendrogram showed two main clusters and separated 30 landraces from the rest 9 landraces. High genetic diversity was detected (0.998) based on the average polymorphism information. Therefore, the used SSRs in the current study provide new insights to reveal the genetic variation among thirty-nine Jordanian tomato landraces. According to functional annotations of the gene-associated SSRs in tomatoes, a few of SSR markers gene-associated markers, for example, LEaat002 and LEaat008 markers are related to MEIS1 Transcription factors genes (Solyc07g007120 and Solyc07g007120.2). The LEaat006 is related to trypsin and protease inhibitor (Kunitz_legume) gene (Solyc03g020010). Also, the SSR LEga003 marker was related to the Carbonic anhydrase gene (Solyc09g010970). CONCLUSIONS: The genetic variation of tomato landraces could be used for considering salt tolerance improvement in tomato breeding programs.

Study of calprotectin gene polymorphism and serum level in acne vulgaris patients.

BACKGROUND: Acne vulgaris (AV) is an inflammatory skin disease of the pilosebaceous unit. S100A8 and S100A9 (the light subunits of calprotectin) gene polymorphisms have been known to be associated with inflammatory disorder. Until now, no study investigated calprotectin gene polymorphism in acne patients. OBJECTIVE: This study was designed to investigate calprotectin serum levels and gene polymorphism (rs3806232) in acne vulgaris patients and to correlate them with different clinical aspects of them. METHODS: This case-control study included 50 patients having variable degrees of acne vulgaris (AV) severity, in addition to a control group of 26 age- and gender-matched seemingly healthy volunteers. RESULTS: Acne vulgaris patients had considerably greater (P < 0.001) mean serum calprotectin levels than the control group (3.86 ± 2.58 pg/ml vs. 0.29 ± 0.14). AA genotype of calprotectin S100 A8 (rs3806232) was significantly predominant over AG or GG genotypes in patients compared to the controls, and the A allele was significantly (P < 0.001) predominant in patients (80%), while A and G alleles were equally distributed in controls; also, there was a significantly higher serum calprotectin level in calprotectin AA genotype than in AG or GG (P < 0.001) in acne vulgaris patients. CONCLUSION: The serum levels of calprotectin were considerably greater in AV patients than in controls. AA genotype and A allele of the S100 A8 gene were significantly higher in patients, which was associated with significantly higher calprotectin serum levels. Thus, calprotectin, both gene and serum level, might participate in disease pathogenesis, which needs further studies.

Genetic analysis toward more nutritious barley grains for a food secure world.

BACKGROUND: Understanding the relationships between nutrition, human health and plant food source is among the highest priorities for public health. Therefore, enhancing the minerals content such as iron (Fe), zinc (Zn) and selenium (Se) in barley (Hordeum vulgare L.) grains is an urgent need to improve the nutritive value of barley grains in overcoming malnutrition and its potential consequencing. This study aimed to expedite biofortification of barley grains by elucidating the genetic basis of Zn, Fe, and Se accumulation in the grains, which will contribute to improved barley nutritional quality. RESULTS: A genome-wide association study (GWAS) was conducted to detect the genetic architecture for grain Zn, Fe, and Se accumulations in 216 spring barley accessions across two years. All the accessions were genotyped by single nucleotide polymorphisms (SNPs) molecular markers. Mineral heritability values ranging from moderate to high were revealed in both environments. Remarkably, there was a high natural phenotypic variation for all micronutrient accumulation in the used population. High-LD SNP markers (222 SNPs) were detected to be associated with all micronutrients in barley grains across the two environments plus BLUEs. Three genomic regions were detected based on LD, which were identified for the most effective markers that had associations with more than one trait. The strongest SNP-trait associations were found to be physically located within genes that may be involved in grain Zn and Fe homeostasis. Two putative candidate genes were annotated as Basic helix loop helix (BHLH) family transcription factor and Squamosa promoter binding-like protein, respectively, and have been suggested as candidates for increased grain Zn, Fe, and Se accumulation. CONCLUSIONS: These findings shed a light on the genetic basis of Zn, Fe, and Se accumulation in barley grains and have the potential to assist plant breeders in selecting accessions with high micronutrient concentrations to enhance grain quality and, ultimately human health.

Exploring natural diversity reveals alleles to enhance antioxidant system in barley under salt stress.

Soil salinity stress causes osmotic/ionic imbalances and induces oxidative stress that causes cellular structure damage, perturbs metabolism, antioxidant system (comprising enzymatic and non-enzymatic components) and hence inhibits plant growth performance. In this study, we used genome-wide association scan (GWAS) in 174 diverse spring barley accessions which were exposed to salt stress under field conditions at the vegetative stage to uncover the genetic basis of antioxidant components and agronomic traits. High activities of enzymatic and content of non-enzymatic antioxidants were observed under salt stress compared to control conditions. Under salt stress, all the agronomic and yield-related traits were significantly reduced. Six genomic regions were associated with antioxidants and agronomic traits under salt stress conditions which were found to be linked with candidate genes. Several significant associations were physically located inside or near genes which are potentially involved in antioxidants. Two candidate genes at 2H (40,659,364 bp) and 7H (416,743,127 bp) were found to be involved in Dihydroflavonol 4-reductase/flavanone protein and Glyceraldehyde-3-phosphate dehydrogenase, respectively. The allelic variation at SNP of BK_07 at 7H inside the GAPDH gene demonstrates a negative selection of accessions carrying A allele. This allele appears in cultivars with lower activity of enzymatic antioxidants e.g. superoxide dismutase and catalases under salt stress conditions. These accessions are predominantly two-rowed, cultivars, originated from Europe, and carrying photoperiod sensitive alleles. The detected associated molecular markers in this work are considered as an important source for selection of increased amount of antioxidant compounds in barley under stress conditions.

Genetic factors controlling nTiO2 nanoparticles stress tolerance in barley (Hordeum vulgare) during seed germination and seedling development.

Titanium dioxide nanoparticle (nTiO2) is one of the most produced nanoparticles worldwide. Its mechanism on crop development and performance is unclear as it is hard to predict their toxicity or benefit. Therefore, understanding the genetics of crop development under nTiO2 is a prerequisite for their applications in agriculture and crop improvement. Here, we aimed to examine the influnce of 300ppm nTiO2 on seed germination, seedling morphology, root-related traits in 121 worldwide spring barley (Hordeum vulgare L.) accessions. Results show that nTiO2 significantley affected all traits scored in this study. Response to nTiO2 treatment, clear wide natural variation among accesions was detected. Remarkably, 10 genotypes showed increased root length under nTiO2 at the seedling stage indicating that nTiO2 enhanced the root elongation. Genome-wide association scan (GWAS) was applied using 9K single nucleotide polymorphism (SNPs) in a mixed-linear model that revealed 86 significant marker-trait associations with all traits scored in this study. Many significant SNPs were physically located near candidate genes, of which 191 genes were detected within the linkage disequilibrium and distributed over all barley chromosomes. Mostly, the genes harboured by chromosome 2H, specially calcium-binding genes family, regulate the variation of seedling length-related traits. Candidate genes on 7H encode zinc finger protein that controls the rate of germination. Therefore, these genomic regions at 2H and 7H can be targeted to select for improved seedling development and seed germination under nTiO2 stress in soils. These results improve understanding the genetic control of seed germination and seedling development under high levels of nTiO2 that can support plant breeding and crop improvement programmes.

Fugitive emissions of polycyclic aromatic compounds from an oil sands tailings pond based on fugacity and inverse dispersion flux calculations.

Alberta's oil sands tailings ponds are suspected to be a source of fugitive emissions of polycyclic aromatic compounds (PACs) to the atmosphere. Here we report, for the first time, fluxes of 6 parent and 21 alkylated PACs based on the measured co-located air and water concentrations using a two-film fugacity-based model (FUG), an inverse dispersion model (DISP) and a simple box model (BOX). Air samples were collected at the Suncor Tailings Pond 2/3 using a high volume air sampler from the "pond" and towards the pond ("non-pond") directions separately. Mean ∑27PACs in air from the "pond" direction was greater than the "non-pond" direction by a factor of 17. Water-air fugacity ratio of 20 PACs quantifiable in water indicated net volatilization from water. Dispersion and box model results also indicated upward fluxes of 22 PACs. Correlation between the estimated flux results of BOX and DISP model was statistically significant (r = 0.99 and p < 0.05), and correlation between FUG and DISP results ranged from 0.54 to 0.85. In this first-ever assessment of PAC fluxes from tailings pond, the three models confirmed volatilization fluxes of PACs indicating Suncor Tailings Pond 2/3 is a source of PAC emissions to the atmosphere. This study addressed a key data gap identified in the Joint Oil Sands Monitoring Emissions Inventory Compilation Report (Government of Alberta and Canada, 2016) which is the lack of consistent real-world tailings pond fugitive emission monitoring of organic chemicals. Our findings highlight the need for measurements from other tailings ponds to determine their overall contribution in releasing PACs to the atmosphere. This paper presents a practical method for estimating PAC emissions from other tailings ponds, which can provide a better understanding of these fugitive emissions, and thereby help to improve the overall characterization of emissions in the oil sands region.