Ethylene Emission Research Articles

Transcriptome profiling reveals regulatory mechanisms underlying corolla senescence in petunia

The genetic regulatory mechanisms that govern natural corolla senescence in petunia are not well understood. To identify key genes and pathways that regulate the process, we performed a transcriptome analysis in petunia corolla at four developmental stages, including corolla fully opening without anther dehiscence (D0), corolla expansion, 2 days after anthesis (D2), corolla with initial signs of senescence (D4), and wilting corolla (D7). We identified large numbers of differentially expressed genes (DEGs), ranging from 4626 between the transition from D0 and D2, 1116 between D2 and D4, a transition to the onset of flower senescence, and 327 between D4 and D7, a developmental stage representing flower senescence. KEGG analysis showed that the auxin- and ethylene-related hormone biosynthesis and signaling transduction pathways were significantly activated during the flower development and highly upregulated at onset of flower senescence. Ethylene emission was detected at the D2 to D4 transition, followed by a large eruption at the D4 to D7 transition. Furthermore, large numbers of transcription factors (TFs) were activated over the course of senescence. Functional analysis by virus-induced gene silencing (VIGS) experiments demonstrated that inhibition of the expression of TFs, such as ethylene-related ERF, auxin-related ARF, bHLH, HB, and MADS-box, significantly extended or shortened flower longevity. Our data suggest that hormonal interaction between auxin and ethylene may play critical regulatory roles in the onset of natural corolla senescence in petunia.

NAC-NOR mutations in tomato Penjar accessions attenuate multiple metabolic processes and prolong the fruit shelf life

Several Penjar accessions of tomato grown in the Mediterranean exhibit prolonged shelf life and harbor alcobaca mutation. To uncover the metabolic basis underlying shelf life, we compared four Penjar accessions to Ailsa Craig. Three accessions bore alcobaca mutation, whereas the fourth was a novel NAC-NOR allele. Cuticle composition of Penjars varied widely during fruit ripening. All Penjars exhibited delayed ripening, prolonged on-vine and off-vine shelf life, low ethylene emission, and carotenoid levels. Metabolic profiling revealed shifts in Krebs cycle intermediates, amino acids, and γ-aminobutyric acid levels indicating the attenuation of respiration in Penjars during post-harvest storage. Penjar fruits also showed concerted downregulation of several cell-wall modifying genes and related metabolites. The high ABA and sucrose levels at the onset of senescence in Penjar fruits likely contribute to reduced water loss. Our analyses reveal that the attenuation of various metabolic processes by NAC-NOR mutation likely prolongs the shelf life of Penjar fruits.

Polyamines Regulate Strawberry Fruit Ripening by Abscisic Acid, Auxin, and Ethylene.

Polyamines (PAs) participate in many plant growth and developmental processes, including fruit ripening. However, it is not clear whether PAs play a role in the ripening of strawberry (Fragaria ananassa), a model nonclimacteric plant. Here, we found that the content of the PA spermine (Spm) increased more sharply after the onset of fruit coloration than did that of the PAs putrescine (Put) or spermidine (Spd). Spm dominance in ripe fruit resulted from abundant transcripts of a strawberry S-adenosyl-l-Met decarboxylase gene (FaSAMDC), which encodes an enzyme that generates a residue needed for PA biosynthesis. Exogenous Spm and Spd promoted fruit coloration, while exogenous Put and a SAMDC inhibitor inhibited coloration. Based on transcriptome data, up- and down-regulation of FaSAMDC expression promoted and inhibited ripening, respectively, which coincided with changes in several physiological parameters and their corresponding gene transcripts, including firmness, anthocyanin content, sugar content, polyamine content, auxin (indole-3-acetic acid [IAA]) content, abscisic acid (ABA) content, and ethylene emission. Using isothermal titration calorimetry, we found that FaSAMDC also had a high enzymatic activity with a Kd of 1.7 × 10-3 m In conclusion, PAs, especially Spm, regulate strawberry fruit ripening in an ABA-dominated, IAA-participating, and ethylene-coordinated manner, and FaSAMDC plays an important role in ripening.

Drought response of Mucuna pruriens (L.) DC. inoculated with ACC deaminase and IAA producing rhizobacteria.

Drought is one of the major constraints limiting agricultural production worldwide and is expected to increase in the future. Limited water availability causes significant effects to plant growth and physiology. Plants have evolved different traits to mitigate the stress imposed by drought. The presence of plant growth-promoting rhizobacteria (PGPR) could play an important role in improving plant performances and productivity under drought. These beneficial microorganisms colonize the rhizosphere of plants and increase drought tolerance by lowering ethylene formation. In the present study, we demonstrate the potential to improve the growth of velvet bean under water deficit conditions of two different strains of PGPR with ACCd (1-Aminocyclopropane-1-Carboxylate deaminase) activity isolated from rainfed farming system. We compared uninoculated and inoculated plants with PGPR to assess: a) photosynthetic performance and biomass; b) ACC content and ethylene emission from leaves and roots; c) leaf isoprene emission. Our results provided evidence that under drought conditions inoculation with PGPR containing the ACCd enzyme could improve plant growth compared to untreated plants. Ethylene emission from roots and leaves of inoculated velvet bean plants was significantly lower than uninoculated plants. Moreover, isoprene emission increased with drought stress progression and was higher in inoculated plants compared to uninoculated counterparts. These findings clearly illustrate that selected PGPR strains isolated from rainfed areas could be highly effective in promoting plant growth under drought conditions by decreasing ACC and ethylene levels in plants.

Household Cookstoves: A Comprehensive Assessment of Health-Relevant Emissions

Background/Aim: Air pollution from biomass and liquid-fuel cookstoves is a leading cause of disease globally. There is a limited understanding, however, of the toxic pollutants emitted by cookstove technologies beyond particulate matter (PM2.5) and carbon monoxide (CO) emissions. The aim of this work was to develop a comprehensive inventory of health-relevant emissions, which will aid in the interpretation of the health impacts from cookstove smoke. Methods: Over 100 gas- and particle-phase emissions from 30 stove-fuel combinations representing both traditional and cleanest-available technologies were measured in the laboratory. The pollutants that were characterized included: CO, black carbon (BC), organic carbon (OC), PM2.5, volatile organic compounds (including BTEX), carbonyls, ultrafine particles, and polycyclic aromatic hydrocarbons (PAHs). Descriptive and statistical analyses were conducted to compare pollutant emissions across stoves and fuels. Results: PM2.5 emissions from traditional wood stoves were consistently the highest (16.5-116.6 mg/MJ), while liquid-fuel stoves were the lowest (kerosene: 0.99-25.3 mg/MJ; LPG: 2.41-5.40 mg/MJ). Higher than expected PM2.5 emissions were also seen from charcoal stoves (12.9-84.4 mg/MJ); we suspect this was due to refueling events. Emissions of known carcinogens varied greatly between stoves. The wick-kerosene stove, which reduced PM2.5 emissions by 80% compared to a three-stone-fire, had the highest average emissions of benzene (107.5 mg/MJ), formaldehyde (34.6 mg/MJ) and acetaldehyde (12.6 mg/MJ), as well as a 380% increase in total BTEX emissions. The gasifier stove had a 65% reduction in PM2.5 and reduced total BTEX emissions by >90%. Conclusions: In the largest cookstove emissions characterization study reported to date, we observed that cookstoves touted as ‘cleaner’ because of their lower PM2.5 emissions may be emitting higher concentrations of other harmful compounds than traditional stoves. We anticipate that the results of this study will inform future health studies, since cookstoves may not be comprehensively evaluated before they are disseminated to users.

1-Aminocyclopropane-1-carboxylate (ACC) Deaminase-Producing Endophytic Diazotrophic Enterobacter sp. EN-21 Modulates Salt–Stress Response in Sugarcane

Soil salinity is a wide-reaching environmental problem that lowers the yield of commercial crops such as maize, rice, and sugarcane. In this study, we examined the effect of 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing endophytic diazotrophic Enterobacter sp. EN-21 on growth promotion, salt tolerance, and root colonization of sugarcane. Enterobacter sp. EN-21 inoculated and uninoculated sugarcane plants were grown in a greenhouse with and without 200 mM NaCl for 7 days. Sugarcane inoculated with Enterobacter sp. EN-21 substantially increased in total plant length, dry, and fresh weights in both non-salt and salt treatments. Under the salt–stress condition, Enterobacter sp. EN-21 significantly reduced proline, malondialdehyde, ethylene emission, and Na+ accumulation in sugarcane but markedly increased total chlorophyll content and K+ accumulation. The gfp-tagged Enterobacter sp. EN-21 was observed to colonize early at the root cap, root hairs, and lateral root junctions of sugarcane and later localized in intercellular spaces. Altogether the results of this study indicated that ACC deaminase-producing Enterobacter sp. EN-21 is a true endophyte and able to promote growth and enhance salt tolerance in sugarcane.

Root cap-mediated evaluation of soil resistance towards graviresponding roots of maize (Zea mays L.) and the relevance of ethylene

Besides biological and chemical impacts, mechanical resistance represents an important obstacle that growing roots face. Graviresponding roots must assess the mechanical resistance of the substrate and take decisions on whether they change growth direction and grow around obstacles or tolerate growth conditions impaired to varying degrees. To test the significance of the root cap, we measured pressure and growth behaviour of single intact, as well as decapped, roots encountering diverse mechanical obstacles. We examined ethylene emission in intact roots as well as roots without a root cap, thereby lacking the capacity to deviate. Roots of fixed seedlings were grown vertically onto diverse mechanical obstacles. Developing pressure profiles of vertically growing roots encountering horizontal mechanical obstacles were measured employing electronic milligram scales, with and without root caps in given local environmental conditions. The evolution of root-borne ethylene was measured in intact roots and roots without the root cap. In contrast to decapped roots, intact roots develop a tentative, short-lasting pressure profile, the resolution of which is characterized by a definite change of growth direction. Similarly, pressure profiles and strengths of roots facing gradually differing surface resistances differ significantly between the two. This correlates in the short term with root cap-dependent ethylene emission which is lacking in roots without caps. The way gravistimulated and graviresponding roots cope with exogenous stimuli depends on whether and how they adapt to these impacts. With respect to mechanical hindrances, roots without caps do not seem to be able to evaluate soil strengths in order to respond adequately. On encountering resistance, roots with intact caps emit ethylene, which is not observed in decapped roots. It therefore appears that it is the root cap which specifically orchestrates the resistance needed to overcome mechanical resistance by specifically inducing ethylene.

MicroRNA1917 targets CTR4 splice variants to regulate ethylene responses in tomato.

Ethylene perception is regulated by receptors, and the downstream protein CONSTITUTIVE TRIPLE RESPONSE1 is a key suppressor of ethylene signalling. The non-conserved tomato (Solanum lycopersicum) microRNA1917 (Sly-miR1917) mediates degradation of SlCTR4 splice variants (SlCTR4sv) but the molecular details of this pathway remain unknown. Sly-miR1917 and the targeted SlCTR4sv are ubiquitously expressed in all tomato organs. Overexpression of Sly-miR1917 enhances ethylene responses, including the triple response in etiolated seedlings, in the absence of ethylene, as well as epinastic petiole growth, accelerated pedicel abscission, and fruit ripening. Enhanced ethylene signalling in Sly-miR1917-overexpressing plants (1917-OE) is accompanied by up-regulation of ethylene biosynthesis and signalling genes, and increased ethylene emission. These phenotypes were recovered by repressing the positive ethylene regulator EIN2. Moreover, the Sly-miR1917-targeted SlCTR4 splice variant SlCTR4sv3, expressed specifically in the abscission zone, exhibited the opposite expression pattern to Sly-miR1917. Complementation of the Arabidopsis thaliana ctr-1 mutant and yeast two-hybrid and bimolecular fluorescence complementation assays suggested that SlCTR4sv3 functions in ethylene signalling. Co-expression of Sly-miR1917 and SlCTR4sv3 in Nicotiana benthamiana further suggested that Sly-miR1917 cleaves SlCTR4sv3 in vivo. Database homology searching revealed a Solanum tuberosum CTR-like splice variant containing a Sly-miR1917 binding sequence, and a homologue of mature Sly-miR1917 in potato, indicating a conserved function for miR1917 and the regulatory miRNA-mediated ethylene network in solanaceous species.

English

Phyllosphere bacteria plays important role in mitigating biotic and abiotic stress. This study aimed to use phyllosphere bacterium of rice to enhance drought tolerance. Bacterial isolates obtained from rice phyllosphere were investigated for their plant growth promoting activities and role in alleviation of drought stress in rice. The isolates were identified as Bacillus altitudinis FD48, Bacillus pumilus FS20 and Bacillus aquimaris MD02 based on 16S rRNA gene sequence. B. altitudinis FD48 was found to produce indole acetic acid (IAA) (2.82 µg/ml) compared to other two isolates even under PEG induced drought conditions. However, under normal conditions, B. altitudinis FD48 produced 8.0 µg/ml. Quantitative estimation of 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity was found to be 192 n moles a-ketobutyrate mg-1 h-1 and positive for accD gene. B. altitudinis FD48 increased the root and shoot length of rice under in vitro conditions and also improved the germination percentage of rice seeds at different concentration of PEG 6000. Inoculation of rice with plant growth promoting, drought tolerant B. altitudinis FD48 increased relative water content, chlorophyll stability index and membrane stability index compared to control (uninoculated plants) when the plants were subjected to drought by discontinuing water for 8 days after 30 days of germination. Similarly, rice treated with B. altitudinis increased proline content, phenolics content, catalase activity and reduced malondialdehyde (MDA) content in plants. Ethylene emission was significantly reduced by B. altitudinis FD48 inoculation under drought condition when compared with control. This study suggests that the isolate B. altitudinis FD48 may be used at field level to mitigate drought stress in rice. Key words: Proline content, drought, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, plant growth promoting bacteria, phenolics content, indole acetic acid (IAA).

Dynamics of Ethylene Production in Response to Compatible Nod Factor.

Establishment of symbiotic nitrogen-fixation in legumes is regulated by the plant hormone ethylene, but it has remained unclear whether and how its biosynthesis is regulated by the symbiotic pathway. We established a sensitive ethylene detection system for Lotus japonicus and found that ethylene production increased as early as 6 hours after inoculation with Mesorhizobium loti This ethylene response was dependent on Nod factor production by compatible rhizobia. Analyses of nodulation mutants showed that perception of Nod factor was required for ethylene emission, while downstream transcription factors including CYCLOPS, NIN, and ERN1 were not required for this response. Activation of the nodulation signaling pathway in spontaneously nodulating mutants was also sufficient to elevate ethylene production. Ethylene signaling is controlled by EIN2, which is duplicated in L. japonicus We obtained a L. japonicus Ljein2a Ljein2b double mutant that exhibits complete ethylene insensitivity and confirms that these two genes act redundantly in ethylene signaling. Consistent with this redundancy, both LjEin2a and LjEin2b are required for negative regulation of nodulation and Ljein2a Ljein2b double mutants are hypernodulating and hyperinfected. We also identified an unexpected role for ethylene in the onset of nitrogen fixation, with the Ljein2a Ljein2b double mutant showing severely reduced nitrogen fixation. These results demonstrate that ethylene production is an early and sustained nodulation response that acts at multiple stages to regulate infection, nodule organogenesis, and nitrogen fixation in L. japonicus.

Correction to: Acetaldehyde emission from wood induced by the addition of ethanol

The article Acetaldehyde emission from wood induced by the addition of ethanol, written by Shin-ichiro Tohmura, Atsuko Ishikawa, Kohta Miyamoto and Akio Inoue, was originally published Online First without open access.

Formaldehyde in the Tropical Western Pacific: Chemical sources and sinks, convective transport, and representation in CAM-Chem and the CCMI models.

Formaldehyde (HCHO) directly affects the atmospheric oxidative capacity through its effects on HOx. In remote marine environments, such as the Tropical Western Pacific (TWP), it is particularly important to understand the processes controlling the abundance of HCHO because model output from these regions is used to correct satellite retrievals of HCHO. Here, we have used observations from the CONTRAST field campaign, conducted during January and February 2014, to evaluate our understanding of the processes controlling the distribution of HCHO in the TWP as well as its representation in chemical transport/climate models. Observed HCHO mixing ratios varied from ~500 pptv near the surface to ~75 pptv in the upper troposphere. Recent convective transport of near surface HCHO and its precursors, acetaldehyde and possibly methyl hydroperoxide, increased upper tropospheric HCHO mixing ratios by ~33% (22 pptv); this air contained roughly 60% less NO than more aged air. Output from the CAM-Chem chemistry transport model (2014 meteorology) as well as nine chemistry climate models from the Chemistry-Climate Model Initiative (free-running meteorology) are found to uniformly underestimate HCHO columns derived from in situ observations by between 4 and 50%. This underestimate of HCHO likely results from a near factor of two underestimate of NO in most models, which strongly suggests errors in NOx emissions inventories and/or in the model chemical mechanisms. Likewise, the lack of oceanic acetaldehyde emissions and potential errors in the model acetaldehyde chemistry lead to additional underestimates in modeled HCHO of up to 75 pptv (~15%) in the lower troposphere.

Emissions of volatile organic compounds (VOCs) from cooking and their speciation: A case study for Shanghai with implications for China

Cooking emission is one of sources for ambient volatile organic compounds (VOCs), which is deleterious to air quality, climate and human health. These emissions are especially of great interest in large cities of East and Southeast Asia. We conducted a case study in which VOC emissions from kitchen extraction stacks have been sampled in total 57 times in the Megacity Shanghai. To obtain representative data, we sampled VOC emissions from kitchens, including restaurants of seven common cuisine types, canteens, and family kitchens. VOC species profiles and their chemical reactivities have been determined. The results showed that 51.26%±23.87% of alkane and 24.33±11.69% of oxygenated VOCs (O-VOCs) dominate the VOC cooking emissions. Yet, the VOCs with the largest ozone formation potential (OFP) and secondary organic aerosol potential (SOAP) were from the alkene and aromatic categories, accounting for 6.8–97.0% and 73.8–98.0%, respectively. Barbequing has the most potential of harming people's heath due to its significant higher emissions of acetaldehyde, hexanal, and acrolein. Methodologies for calculating VOC emission factors (EF) for restaurants that take into account VOCs emitted per person (EFperson), per kitchen stove (EFkitchen stove) and per hour (EFhour) are developed and discussed. Methodologies for deriving VOC emission inventories (S) from restaurants are further defined and discussed based on two categories: cuisine types (Stype) and restaurant scales (Sscale). The range of Stype and Sscale are 4124.33–7818.04t/year and 1355.11–2402.21t/year, respectively. We also found that Stype and Sscale for 100,000 people are 17.07–32.36t/year and 5.61–9.95t/year, respectively. Based on Environmental Kuznets Curve, the annual total amount of VOCs emissions from catering industry in different provinces in China was estimated, which was 5680.53t/year, 6122.43t/year, and 66,244.59t/year for Shangdong and Guangdong provinces and whole China, respectively. Large and medium-scaled restaurants should be paid more attention with respect to regulation of VOCs.

Glutathione-induced alleviation of cadmium toxicity in Zea mays

Glutathione (GSH) is known to alleviate cadmium (Cd) stress in many plant species. However, the comprehensive mechanisms responsible for this effect in maize are still need more investigation. Here, a combination of physiological and molecular approaches was utilized in GSH-Cd treated maize seedlings, which revealed that GSH reversed the adverse effects of Cd, as reflected by plant growth, plant hormones, vacuole, stoma development, gene expression, etc. Plant growth, root cell viability, photosynthetic capacity, redox equilibrium, and cell ultrastructure recovery following GSH treatment, coupled with the strong up-regulation of Cd tolerance-related genes (e.g., phytochelatin synthetase-like protein, MYB and WRKY transcription factors, and CYP450), demonstrated the efficient activation of cellular defense against Cd toxicity. The addition of GSH significantly elevated GSH/GSSG ratio and the activity of γ-glutamylcysteine synthetase in both shoots and roots and markedly reduced Cd concentration in shoots. Ethylene emission rate and abscisic acid (ABA) content were significantly reduced after GSH application in the presence of Cd, except ABA content in leaves. These findings highlighted the significance of GSH in alleviating Cd-stress in maize and indicate a promising strategy for safe food production.

Combustion and emissions characteristics of a diesel engine fueled with blends of diesel and DMF

With the petroleum storage reduction and global warming, there is an increasing need to revolutionize the energy supply chain, especially in the transportation industry. Researches on the production of fuels derived from biological renewable feedstocks have been greatly intensified over the past decade. Sustained researches have been performed with biofuels, such as bioethanol which is the most commonly used in SI engines due to its renewable nature and high octane number. Apart from SI engines, bioethanol is also used in diesel engines. Our country population resources are numerous, it is impossible to popularize the bioethanol in large scale due to the limitation of the area of cultivated land. With the development of fuel production technology, more and more alternative fuel for diesel have been found, such as 2,5-dimethylfuran (DMF). In the past, DMF did not draw extensive attention due to the limitation of production technology. Recently, some significant breakthroughs have been made in production methods for DMF, which makes it is possible to be widely applied as a major alternative fuel for diesel in compression ignition engine. Although DMF is a promising biofuel, little is known on its combustion and emission characteristics. The experiments were carried out on a modified four-cylinder, 4-stroke, water-cooled, DICI engine coupled with a common rail fuel injection system using blends of diesel and DMF. Conventional diesel fuel was used as the base fuel. Mixtures of 10% and 30% by mass fraction of DMF with the base diesel fuel were tested in the research, referred to as D10 and D30, respectively. Traditional pure diesel referred to as D0. The experimental conditions were constant engine speed of 1800 r min −1 and loads from 10% to 90% at an interval of 20%, corresponding to 0.13, 0.38, 0.63, 0.88 and 1.13 MPa BMEP, respectively. Unregulated emissions would severely harm the health of humans and other living beings. Some of the unregulated emissions, even in minor quantities into the air, can induce major health problems in large sections of the affected population. There is much research on the regulated emissions of DMF, but rarely on the unregulated emissions of formaldehyde, acetaldehyde or benzene. Airborne particulate matter (PM) is also associated with several severe health hazards. Thus, we studied the combustion and unregulated emission characteristics as well as PM emission from diesel engine on different DMF and diesel blends compared with baseline diesel. The results show that at 0.13 MPa BMEP, with the increase of DMF mass fraction in the mixtures, the peak cylinder pressure decreases significantly and the peak heat release rate (HRR) significantly increases. However, at 0.88 MPa BMEP, peak cylinder pressure and HRR are increased with the increase of DMF mass fraction. 1,3-butadiene, acetaldehyde and benzene emissions are decreased with the increase of engine load. The NO x emissions increases with the increase of engine load. In addition, DMF blending with diesel increased acetaldehyde emissions, whilst reduced 1,3-butadiene and benzene emissions. At 0.13 MPa BMEP, D30 has the lowest NO x emissions. For each tested fuels, the nucleation mode greatly dominates the particle size distribution. At 0.38 MPa BMEP, compared with diesel, the particle number concentration of blend fuels are lower in each test mode. However, at high load of 1.13 MPa BMEP, the particle number concentration of diesel is consistently the lowest within the entire range of diameters. At 0.88 MPa BMEP, D30 has 60.5% smaller nucleation-mode number and 232.2% smaller accumulation-mode mass than diesel. D30 has much smaller mean accumulation-mode diameter than diesel (50.9 vs. 60.1 nm).

Real-world volatile organic compound emission rates from seated adults and children for use in indoor air studies.

Human beings emit many volatile organic compounds (VOCs) of both endogenous (internally produced) and exogenous (external source) origin. Here we present real-world emission rates of volatile organic compounds from cinema audiences (50-230 people) as a function of time in multiple screenings of three films. The cinema location and film selection allowed high-frequency measurement of human-emitted VOCs within a room flushed at a known rate so that emissions rates could be calculated for both adults and children. Gas-phase emission rates are analyzed as a function of time of day, variability during the film, and age of viewer. The average emission rates of CO2 , acetone, and isoprene were lower (by a factor of ~1.2-1.4) for children under twelve compared to adults while for acetaldehyde emission rates were equivalent. Molecules influenced by exogenous sources such as decamethylcyclopentasiloxanes and methanol tended to decrease over the course of day and then rise for late evening screenings. These results represent average emission rates of people under real-world conditions and can be used in indoor air quality assessments and building design. Averaging over a large number of people generates emission rates that are less susceptible to individual behaviors.

Particulate matter and unregulated emissions of diesel engine fueled with 2-methylfuran diesel blends

2-Methylfuran (MF), an environmental-friendly biofuel, has drawn extensive attention from fuel researchers. In this study, the particulate matter (PM) and unregulated emissions of diesel engine were investigated. All experiments were performed in a direct injection compression ignition (DICI) engine fueled with diesel–MF blends (10%, 20% and 30% mass fractions of MF were blended with diesel). The test conditions were a constant speed of 1800rpm and load from 0.13 to 1.13MPa brake mean effective pressure (BMEP). Among the tested fuels, the emissions of 1,3-butadiene, benzene and acetaldehyde are all decreased with the increase of engine load except benzene of M30 at 1.13 load. In addition, the diesel–MF blends promote acetaldehyde emissions, but reduce benzene and 1,3-butadiene emissions. At the engine load of 0.38MPa BMEP, with the increase of MF fraction in blends, more particle numbers for both nucleation mode and accumulation mode are yielded than pure diesel. At 0.88 and 1.13MPa BMEP, with the increment of MF ratio in blend fuels, the particle numbers rise at small diameter of particle (Dp) (5–10nm) compared to pure diesel, but decline at large diameter of particle (Dp) (10–250nm). The increment of MF blending ratio increases the particulate number concentration. Moreover, with the rise of MF mass fraction in the mixtures, the particulate mass concentration decreases gradually at above 0.63MPa BMEP. However, particulate mass concentration of M30 is the highest at lower loads.

Enhanced tolerance to salt stress in canola (Brassica napus L.) seedlings inoculated with the halotolerant Enterobacter cloacae HSNJ4

Using halotolerant plant growth-promoting rhizobacteria (PGPR) to alleviate damages caused by salt stress is an effective method in agriculture. In the present study, an Enterobacter cloacae strain (HSNJ4) that was isolated from the rhizosphere of saline soil was found to be the most effective for promoting canola seed germination among eight halotolerant bacteria tested. Then, the effects of HSNJ4 inoculation on the growth and physiological responses of canola seedlings were investigated under three different levels of salt stress in a pot experiment. The root length, shoot length, amount of lateral roots, and chlorophyll content in HSNJ4-inoculated canola seedlings increased significantly under salt stress. Physiological analysis showed that malondialdehyde content was decreased, whereas proline content and antioxidant enzyme activity were increased by HSNJ4 inoculation at NaCl concentrations of 50 and 100mM. Moreover, HSNJ4 inoculation effectively increased endogenous indole-3-acetic acid (IAA) content and reduced ethylene emission under simulated salt stress conditions. Cultures of HSNJ4 demonstrated that under conditions of salt stress, HSNJ4 could indeed produce both IAA and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Hence, it is plausible that HSNJ4 balances the relative content of IAA and ethylene in canola seedlings to enhance their salt tolerance.

Beneficial Soil Bacterium Pseudomonas frederiksbergensis OS261 Augments Salt Tolerance and Promotes Red Pepper Plant Growth.

Soil salinity, being a part of natural ecosystems, is an increasing problem in agricultural soils throughout the world. Pseudomonas frederiksbergensis OS261 has already been proved to be an effective bio-inoculant for enhancing cold stress tolerance in plants, however, its effect on salt stress tolerance is unknown. The main aim of the present study was to elucidate P. frederiksbergensis OS261 mediated salt stress tolerance in red pepper. The plants were exposed to a salt stress using NaCl at the concentrations of 50, 100, and 150 mM after 12 days of transplantation, while plant growth and enzyme activity were estimated 50 days after sowing. The height in P. frederiksbergensis OS261 inoculated plants was significantly increased by 19.05, 34.35, 57.25, and 61.07% compared to un-inoculated controls at 0, 50, 100, and 150 mM of NaCl concentrations, respectively, under greenhouse conditions. The dry biomass of the plants increased by 31.97, 37.47, 62.67, and 67.84% under 0, 50, 100, and 150 mM of NaCl concentrations, respectively. A high emission of ethylene was observed in un-inoculated red pepper plants under salinity stress. P. frederiksbergensis OS261 inoculation significantly reduced ethylene emission by 20.03, 18.01, and 20.07% at 50, 100, and 150 mM of NaCl concentrations, respectively. Furthermore, the activity of antioxidant enzymes (ascorbate peroxidase, superoxide dismutase, and catalase) also varied in the inoculated red pepper plants. Salt stress resistance in the bacterized plants was evident from the improved antioxidant activity in leaf tissues and the decreased hydrogen ion concentration. Thus, we conclude that P. frederiksbergensis OS261 possesses stress mitigating property which can enhance plant growth under high soil salinity by reducing the emission of ethylene and regulating antioxidant enzymes.

Intercomparison of ethanol, formaldehyde and acetaldehyde measurements from a flex-fuel vehicle exhaust during the WLTC

An intercomparison exercise of the world-harmonized light-duty vehicle test procedure (WLTP) aiming at measuring ethanol, formaldehyde and acetaldehyde emissions from a flex-fuel light-duty vehicle using E85 was conducted in the Vehicle Emission Laboratory (VELA) at the European Commission Joint Research Centre (EC-JRC), Ispra, Italy. The instruments used during the intercomparison allowed online measurements of these compounds directly from the diluted exhaust. Measurements were done either in real time or immediately after the test. The measurement and analysis of exhaust emissions over the world-harmonized light-duty vehicle test cycle was done by means of Fourier transform infrared spectroscopy (FTIR), proton transfer reaction-mass spectrometry (PTR-Qi-ToF-MS), photoacoustic spectroscopy (PAS) and gas chromatography (GC). Results showed that online systems can perform measurements from the vehicle diluted exhaust assuring a good repeatability (within instrument variance) and reproducibility (between instrument variance) of the results. Measurements from all the instruments were in good agreement (|Z-score|<2). Results showed that online systems can perform measurements from the vehicle diluted exhaust assuring the reproducibility and repeatability of the results. Results obtained measuring at the tailpipe using a FTIR were in good agreement with those acquired measuring at the constant volume sampler (CVS). Considering the low sensitivity of the current technique used to measure hydrocarbons emissions towards oxygenated compounds (flame ionization detector; FID), non-methane organic gases (NMOG) were calculated applying their FID response factors to the measured emissions of ethanol, acetaldehyde and formaldehyde. NMOG resulted to be up to 74% higher than measured non-methane hydrocarbons (NMHC).