Ethylene Production Research Articles

Facile production of ethyl furfuryl ether via reductive etherification of furfural over Rh nanoparticles supported red mud as a catalyst

Reducing reliance on fossil fuels and mitigating industrial waste are two strategies for clean environmental management. An active research topic within this framework is to convert abundant bio-derived compounds, like furfural (FF), into a petroleum blend by employing industrial waste, like red mud (RM), as catalyst support. Here, we demonstrate that furfural can be chemoselectively converted in a single step into ethyl furfuryl ethers (EFE), which significantly enhance the blended petroleum's octane number. This is achieved in the presence of a recyclable Rh-impregnated RM catalyst. In this context, a range of valuable metals (M = Rh, Ir, and Ru) are impregnated into the RM (M@RM) and extensively characterized by SEM, EDS, XRD, FT-IR, TEM, and XPS. The 1% Rh@RM composite,calcined at 400 °C (1% Rh@RM-400), produced 75 % EFE selectivity with the >99 % conversion of furfural. The prepared catalyst retains its stability for the multiple cycles of the furfural hydrogenation reactions.

Genome-wide isolation and expression analysis of vacuolar processing enzyme (VPE) gene family in four apple cultivars with different storability

ABSTRACT This research was undertaken to determine expression patterns of vacuolar processing enzyme (VPE) genes in four apple (Malus domestica (Suckow) Borkh) cultivars ‘Royal Gala (RG)’, ‘Golden Delicious (GD)’, ‘Ralls Janet (RJ)’ and ‘Fuji (FJ)’ during ripening. The results showed that GD and RG had higher respiration rate, ethylene production, content of malondialdehyde (MDA), relative electrical conductivity (REC) and VPE activity than RJ and FJ during ripening. A total of 17 MdVPEs were found to be expressed in four cultivars. These MdVPEs exhibited different expression patterns during ripening of four cultivars. Generally, MdVPEβ1, MdVPEγ2, MdVPEγ4 and MdVPEδ7 might be closely associated with ripening of all cultivars. MdVPEα6 might have a role in the early period of ripening of ACS1–2/-2 (1-Aminocyclopropane-1-carboxylate synthase) homozygous cultivars (RG, RJ and FJ). Our data here would be helpful in understanding the associations between MdVPEs and storage properties of different apple cultivars.

Synthetic auxin herbicide 2,4-D and its influence on a model BY-2 suspension.

2,4-D is a broadly used auxin herbicide. The presence of the 2,4-D synthetic auxin in the medium is imperative for long-term BY-2 tobacco suspension viability. The precise mechanism of this symbiosis of the suspension and the synthetic auxin remains unclear. Our goal was to study the hormonal regulation of the growth of the cell suspension; and to describe the experiments clarifying the interaction between the chosen growth regulators and phytohormones on the cellular level, specifically between the 2,4-D synthetic auxin and the native stress phytohormone - ethylene. This study examined the influence of low 2,4-D concentrations stimulating cell growth in vitro as well as the influence of high herbicide concentrations on the model tobacco BY-2 suspension. The culture took 6 days. Different parameters were evaluated, including the influence of different 2,4-D concentrations on the production of the phytohormone ethylene and its precursor 1-Aminocyclopropane-1-carboxylic acid (ACC) in the tobacco cells. The content of 2,4-D in the cells and the medium was established. The observations of the morphological changes showed that a heavy impregnation of the cell walls taking place depending on the concentration of 2,4-D. A dramatic increase in protective polysaccharides and a remodulation of the cell walls by the formation of a pectin shield in artificial conditions were expected and observed. At the same time, massive production of the stress phytohormone ethylene took place, and, because of that, plant mutagenicity, anomalous tumour-type proliferation growth, and the production of supercells were observed. The hypothesis of the protective shield is discussed.

Targeted C-O bond cleavage of *CH2CHO at copper active sites for efficient electrosynthesis of ethylene from CO2 reduction

*CH2CHO, a pivotal intermediate in CO2 reduction reaction (CO2RR) on copper-based catalysts, hinges on the strength of Cu-C and C-O bonds for the selective production of ethanol and ethylene. However, the targeted cleavage of these bonds at Cu active sites presents a formidable challenge. In this study, we manipulated the selective C-O bond breaking at Cu through an electron enrichment strategy, steering the reaction towards ethylene synthesis. Both experimental and theoretical investigations reveal that Gd incorporation elevates electron density at Cu sites, thereby enhancing Cu-O interaction and concurrently weakening the C-O bond at the critical Cu-*O-CHCH2 bifurcation point. Notably, Gd-doped Cu2O (Gd-Cu2O) demonstrated a 1.43-fold increase in the ethylene/CO ratio relative to undoped Cu2O. This alteration steers the reaction mechanism towards ethylene generation. Our study highlights the pivotal role of regulating reaction intermediates in optimizing activity and selectivity of CO2RR in copper-based catalysts, providing valuable insights for future catalyst development.

Studies on the effect of cinnamon essential oil-micelles combined with 1-MCP/PVA film on postharvest preservation of apricots

Apricot is respiration climacteric fruit. They have high postharvest respiratory intensity, high ethylene release and are easily infected by pathogenic fungi, which greatly shortens the postharvest storage life. This study investigated the effect of Cinnamon essential oil-micelles (CEO-micelles) and biodegradable polymer Polyvinyl Alcohol (PVA) eletrospunning nano fibers films based 1-Methylcyclopropene-Polyvinyl Alcohol films (1-MCP/PVA films) on the quality and antioxidant enzyme activities of apricots during storage. The results showed that compared with CEO-micelles or 1-MCP/PVA films treatment alone, the 1-MCP/PVA + CEO-micelles combined treatment could more effectively inhibit the decay of apricots, reduce the peak value of respiration rate and ethylene production, delay the decrease of loss-weight rate, firmness, total soluble solids (TSS) and titratable acid (TA), and maintain better appearance. In addition, compared with single treatment, combined treatment significantly decreased the accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2), increased the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), and inhibited the increase of polyphenol oxidase (PPO) activity. These results showed that the combination of CEO-micelles and 1-MCP fibers could effectively inhibit the deterioration of fruit quality, improve the antioxidant capacity of apricots and delay postharvest senescence.

Impacts of 1-methylcyclopropene (1-MCP) and ethephon treatments on expression of aquaporin (AQP) genes during apple fruit ripening

The main aim of the present study was to determine the effects of ethephon (ET) and 1-methylcyclopropene (1-MCP) treatments on expression of aquaporin (AQP) genes during apple fruit ripening. The harvested apples were treated with 1-MCP (1 μL L−1) and ET (0.2 mmol L−1), respectively, and then ripened at room temperature (20 ± 1 °C). Our results suggested that 1-MCP application reduced weight loss, total soluble solids (TSS) content, respiration rate and ethylene production, maintained flesh firmness, and slowed down the increase in content of soluble sugar and the decrease in content of titratable acidity (TA) and dry matter concentration (DMC) in flesh and peel during ripening compared with the control, while ET treatment had the opposite effects. Quantitative real-time PCR (qPCR) analysis indicated that MdAQPs expression was differentially regulated by both treatments in flesh and peel during ripening. Expression of MdSIP1;2 and MdNIP5;3 in flesh and MdPIP1;3 and MdPIP2;7 in peel was generally up-regulated by both treatments, while MdTIP4;2 expression in peel was down-regulated by both treatments during ripening. Expression of MdNIP1;1, MdNIP2;1 and MdTIP1;1 in flesh and MdTIP2;2, MdTIP3;1 and MdNIP5;1 in peel was differentially down-regulated by ET treatment while differentially up-regulated by 1-MCP application during ripening. Transcript levels of MdTIP2;2, MdPIP1;2, MdPIP2;4, MdPIP2;3 and MdNIP5;2 in flesh and MdNIP2;1, MdSIP2;2, MdSIP1;2 and MdNIP1;1 in peel were differentially up-regulated by ET application while differentially reduced by 1-MCP application during ripening. After transient over-expression of MdERF2, MdAQPs exhibited varying expression profiles in both tissues during ripening. The results indicated that MdAQPs expression was modulated by ethylene signal in ripening apple fruit.

Chimeric mutations in grapevine ENHANCED DISEASE RESISTANCE1 improve resistance to powdery mildew without growth penalty.

Grapevine (Vitis vinifera L.) incurs severe quality degradation and yield loss from powdery mildew, a major fungal disease caused by Erysiphe necator. ENHANCED DISEASE RESISTANCE1 (EDR1), a Raf-like mitogen-activated protein kinase kinase kinase, negatively regulates defense responses against powdery mildew in Arabidopsis (Arabidopsis thaliana). However, little is known about the role of the putatively orthologous EDR1 gene in grapevine. In this study, we obtained grapevine VviEDR1-edited lines using CRISPR/Cas9. Plantlets containing homozygous and bi-allelic indels in VviEDR1 developed leaf lesions shortly after transplanting into the soil and died at the seedling stage. Transgenic plants expressing wild-type VviEDR1 and mutant Vviedr1 alleles as chimera (designated as VviEDR1-chi) developed normally and displayed enhanced resistance to powdery mildew. Interestingly, VviEDR1-chi plants maintained a spatiotemporally distinctive pattern of VviEDR1 mutagenesis: while almost no mutations were detected from terminal buds, ensuring normal function of the apical meristem, mutations occurred in young leaves and increased as leaves matured, resulting in resistance to powdery mildew. Further analysis showed that the resistance observed in VviEDR1-chi plants was associated with callose deposition, increased production of salicylic acid and ethylene, H2O2 production and accumulation, and host cell death. Surprisingly, no growth penalty was observed with VviEDR1-chi plants. Hence, this study demonstrated a role of VviEDR1 in the negative regulation of resistance to powdery mildew in grapevine and provided an avenue for engineering powdery mildew resistance in grapevine.

GLABRA 2 regulates ETHYLENE OVERPRODUCER 1 accumulation during nutrient deficiency-induced root hair growth.

Root hairs (RHs), extensive structures of root epidermal cells, are important for plant nutrient acquisition, soil anchorage, and environmental interactions. Excessive production of the phytohormone ethylene (ET) leads to substantial root hair growth, manifested as tolerance to plant nutrient deficiencies. However, the molecular basis of ET production during root hair growth in response to nutrient starvation remains unknown. Herein, we found that a critical transcription factor, GLABRA 2 (GL2), inhibits ET production during root hair growth in Arabidopsis (Arabidopsis thaliana). GL2 directly binds to the promoter of the gene encoding ET OVERPRODUCER 1 (ETO1), one of the most important ET-production-regulation factors, in vitro and in vivo, and then regulates the accumulation and function of ETO1 in root hair growth. The GL2-regulated-ETO1 module is required for promoting root hair growth under nitrogen, phosphorus, or potassium deficiency. Genome-wide analysis revealed numerous genes, such as ROOT HAIR DEFECTIVE 6-LIKE 4, ETHYLENE-INSENSITIVE 3-LIKE 2, ROOT HAIR SPECIFIC 13, are involved in the GL2-regulated-ETO1 module. Our work reveals a key transcription mechanism in the control of ET production during root hair growth under three major nutrient deficiencies.

(111) Facet-oriented Cu2Mg Intermetallic Compound with Cu3-Mg Sites for CO2 Electroreduction to Ethanol with Industrial Current Density.

The efficient ethanol electrosynthesis from CO2 is challenging with low selectivity at high CO2 electrolysis rates, due to the competition with H2 and other reduction products. Copper-based bimetallic electrocatalysts are potential candidates for the CO2-to-ethanol conversion, but the secondary metal has mainly been focused on active components (such as Ag, Sn) for CO2 electroreduction, which also promote selectivity of ethylene or other reduction products rather than ethanol. Limited attention has been given to alkali-earth metals due to their inherently active chemical property. Herein, we rationally synthesized a (111) facet-oriented nano Cu2Mg (designated as Cu2Mg(111)) intermetallic compound with high-density ordered Cu3-Mg sites. The in situ Raman spectroscopy and density function theory calculations revealed that the Cu3 - --Mg- + active sites allowed to increase *CO surface coverage, decrease reaction energy for *CO-CO coupling, and stabilize *CHCHOH intermediates, thus promoting the ethanol formation pathway. The Cu2Mg(111) catalyst exhibited a high FEC2H5OH of 76.2±4.8 % at 600 mA⋅cm-2, and a peak value of |jC2H5OH| of 720±34 mA⋅cm-2, almost 4 times of that using conventional Cu2Mg with (311) facets, comparable to the best reported values for the CO2-to-ethanol electroreduction.

(111) Facet‐oriented Cu2Mg Intermetallic Compound with Cu3‐Mg Sites for CO2 Electroreduction to Ethanol with Industrial Current Density

AbstractThe efficient ethanol electrosynthesis from CO2 is challenging with low selectivity at high CO2 electrolysis rates, due to the competition with H2 and other reduction products. Copper‐based bimetallic electrocatalysts are potential candidates for the CO2‐to‐ethanol conversion, but the secondary metal has mainly been focused on active components (such as Ag, Sn) for CO2 electroreduction, which also promote selectivity of ethylene or other reduction products rather than ethanol. Limited attention has been given to alkali‐earth metals due to their inherently active chemical property. Herein, we rationally synthesized a (111) facet‐oriented nano Cu2Mg (designated as Cu2Mg(111)) intermetallic compound with high‐density ordered Cu3‐Mg sites. The in situ Raman spectroscopy and density function theory calculations revealed that the Cu3− −‐Mg− + active sites allowed to increase *CO surface coverage, decrease reaction energy for *CO−CO coupling, and stabilize *CHCHOH intermediates, thus promoting the ethanol formation pathway. The Cu2Mg(111) catalyst exhibited a high FEC2H5OH of 76.2±4.8 % at 600 mA⋅cm−2, and a peak value of |jC2H5OH| of 720±34 mA⋅cm−2, almost 4 times of that using conventional Cu2Mg with (311) facets, comparable to the best reported values for the CO2‐to‐ethanol electroreduction.

Novel ethane recovery process from natural gas using ZIF-8/water–glycol slurry: Techno-economic and energy consumption evaluation

Ethane recovery is a vital step in natural gas processing and can provide raw material for ethylene production. The widely used cryogenic separation process is energy intensive, and the absorption-adsorption coupling process based on porous ZIF-8 slurry (SorbPro I) has been proven to be more energy-efficient. To further reduce energy consumption, this paper proposes a novel process with two absorption-adsorption columns (SorbPro II) and establishes its mathematical model by equilibrium stage method. Taking the natural gas with an ethane content of 6.19 mol% at 300,000 Nm3/d as a case study, the operating parameters of SorbPro I and SorbPro II are optimized by sensitivity analysis, and ethane recovery ratio of both processes can reach 90 %. The techno-economic/energy consumption evaluations of the two processes are conducted. Results show that the total annualized cost and the energy consumption per Nm3 feed gas of SorbPro II are 41.7 % and 47.7 % lower than those of SorbPro I, respectively. It indicates that SorbPro II has the same separation performance as SorbPro I, but is more economical.

Salicylic Acid Spray Delays Sand Pear Fruit Senescence during Room Temperature Shelf Life by Regulating Antioxidant Capacity and Senescence-Related Genes.

'Whangkeumbae' (Pyrus pyrifolia) is a variety of sand pear fruit well-known for its smooth surface and good taste. However, the fruit quality is adversely affected by postharvest ethylene production. Therefore, improving postharvest shelf life by regulating fruit senescence is critical to promoting the 'Whangkeumbae' fruit industry. Here, we investigated the effect of salicylic acid (SA) spray on fruit senescence in sand pears during room temperature shelf life. Exogenous SA reduced polyphenol oxidase (PPO) activity and malondialdehyde (MDA) content during room temperature shelf life. Additionally, SA effectively maintained the fruit skin coloration and increased the activity of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). SA treatment inhibited PpPPO1 expression and upregulated PpSOD1, PpAPX6, and PpGST2 expression. Furthermore, SA application downregulated the expression of PpACO2, PpEIN3a, PpNCED1, and PpAOC2, while upregulating PpNPR-1, PpTAR2, and PpCOMT1 during room temperature shelf life. SA treatment also influenced cell wall metabolism and modification genes by inhibiting PpPG1, PpPME2, and PpCEL3 and inducing PpPGIP1 expression. Additionally, SA treatment affected sugar and acid metabolism genes and increased the expression of PpSPS1, PpSUS1, PpSOT1, PpTMT4, PpSWEET15, and PpcyNAD-MDH, but suppressed the expression of PpcyNADP-ME. The Pearson correlation analysis indicated that PPO activity and MDA content were positively correlated with the expression of PpPPO1, PpACO2, PpEIN3a, PpNCED1, PpAOC2, PpPG1, PpPME2, PpCEL3, and PpcyNDA-MDH. Conversely, these factors were negatively associated with the activities of SOD, POD, CAT, and APX, as well as the expression levels of PpSOD1, PpPOD1, PpCAT1, PpAPX6, PpGST2, PpNPR-1, PpTAR2, PpCOMT1, PpPGIP1, PpSPS1, PpSUS1, PpSOT1, PpTMT4, PpSWEET15, and PpcyNAD-MDH. Our results reveal that exogenous SA could delay fruit senescence in sand pear fruit by regulating various biochemical and molecular mechanisms and can be used to effectively extend fruit shelf life during room temperature storage. However, further research is necessary to determine whether the fruits sprayed with SA are suitable for direct human consumption.

The OsEIL1-OsWOX11 transcription factor module controls rice crown root development in response to soil compaction.

Optimizing the root architecture of crops is an effective strategy for improving crop yields. Soil compaction is a serious global problem that limits crop productivity by restricting root growth, but the underlying molecular mechanisms are largely unclear. Here, we show that ethylene stimulates rice (Oryza sativa) crown root development in response to soil compaction. First, we demonstrate that compacted soil promotes ethylene production and the accumulation of ETHYLENE INSENSITIVE 3-LIKE 1 (OsEIL1) in rice roots, stimulating crown root primordia initiation and development, thereby increasing crown root number in lower stem nodes. Through transcriptome profiling and molecular analyses, we reveal that OsEIL1 directly activates the expression of WUSCHEL-RELATED HOMEOBOX 11 (OsWOX11), an activator of crown root emergence and growth, and that OsWOX11 mutations delay crown root development, thus impairing the plant's response to ethylene and soil compaction. Genetic analysis demonstrates that OsWOX11 functions downstream of OsEIL1. In summary, our results demonstrate that the OsEIL1-OsWOX11 module regulates ethylene action during crown root development in response to soil compaction, providing a strategy for the genetic modification of crop root architecture and grain agronomic traits.

Continuous Production of Ethylene and Hydrogen Peroxide from Paired Electrochemical Carbon Dioxide Reduction and Water Oxidation

AbstractPaired electrolysis offers an auspicious strategy for the generation of high‐value chemicals, at both the anode and cathode, in an integrated electrochemical reactor. Through efficient electron utilization, routine product misuse at overlooked electrodes can be prevented. Here, an original paired electrosynthetic system is reported that can convert CO2 to ethylene (C2H4) at the cathode, and water to hydrogen peroxide (H2O2) at the anode under a single pass of electric charge. Amongst various investigated copper (Cu) nanomorphologies, the bespoke mixed Cu nanowire/nanoparticle catalyst recorded a peak C2H4 Faraday efficiency (FE) of 60% following 370 h of electrolysis at 200 mA cm−2, while the tailored boron‐doped diamond (BDD) anode accumulated an unprecedented ≈1% w/w of H2O2 in 4 m K2CO3 upon applying 300 mA cm−2 for 10 h. When paired, the dual C2H4‐H2O2 electrochemical cell attains a combined FE of 120% for 50 h at 200 mA cm−2, a combined energy efficiency (EE) of 69%, and a 50% decrease in the overall electrical energy consumption (EEC) compared to the individual electrosynthesis of C2H4 and H2O2.

ACC-Deaminase producing Pseudomonas putida RT12 inoculation: A promising strategy for improving Brassica juncea tolerance to salinity stress

An important abiotic stressor that hinders plant growth, nutrient uptake, and global agricultural productivity is soil salinity. Among the different strategies to overcome the issue of salinity in agriculture sector, plant growth-promoting rhizobacteria (PGPR) have gained recognition as promising beneficial microbes that can improve plants’ response to biotic and abiotic stressors. The salinity tolerance and traits that promote plant growth of eight PGPR strains (RT1, RT2, RT3, RT4, RT5, RT7, and RT12) were evaluated in this study. During screening, one strain, RT12, had the highest plant growth-promoting activity and salt tolerance in the group. The strain when subjected to NaCl stress showed quantitative ACC-deaminase activity, in the presence of NaCl at various concentrations, demonstrating extraordinary tolerance to salt stress by withstanding doses of up to 3M NaCl. In order to further investigate the effects of salt stress on Brassica juncea (mustard), RT12, which was identified as Pseudomonas putida using 16s RNA sequencing, was inoculated. Two salt treatments (100 and 150 mM) were applied to the mustard variety ‘Mingora’ in a greenhouse. The results revealed that through ACC utilization, PGPR directly induced plant growth in salt-stressed mustard plants by lowering excess ethylene production. All plant parameters were negatively impacted by an increase in NaCl concentration in uninoculated plants. However, P. putida RT12 inoculation enhanced all growth parameters, antioxidant production, total soluble sugar (TSS), total protein (TP), proline, relative water content (RWC), chlorophyll contents, and nutrient uptake in salt-treated plants. The inoculation with P. putida also caused a marked decline in Na+ uptake and an increase in K+ uptake in the shoot. By maintaining a greater K+/Na+ ratio in the tissues of RT12-inoculated plants compared to controls, this change in ion uptake helped to maintain nutritional balance of the plants. The findings suggest that inoculating plants with ACC deaminase-producing PGPR, such as P. putida RT12, may boost growth and stress resistance.

Efficient ethylene degradation in storage bananas by Bi–Mn catalyst at room temperature

There has been growing interest in removing ethylene (C2H4) from fresh fruit packaging to prevent its detrimental effects on fruit quality. Thus, creating innovative, efficient, and simple catalysts capable of degrading C2H4 at room temperature is imperative for fruit preservation. We demonstrated that the bismuth-manganese (Bi–Mn) catalysts, synthesized using the stepwise hydrothermal method, can degrade up to 40% of 50 ppm C2H4 in 6 h at room temperature. Doping with the Bi element resulted in an irregular broccoli-like catalyst with a specific surface area of up to 71.66 m2/g more surface Mn vacancies, a higher Mn3+/Mn4+ ratio, and increased oxygen adsorption capacity. The catalyst extended banana shelf life by 3–5 days, unprecedentedly maintaining the overall sensory quality at the desired level. The catalyst was effective in reducing ethylene production by 45.2% at 25 °C storage. Banana respiration rates were also effectively reduced by 17.2% and 38.2% after 5 days of storage. The catalyst efficiently controlled banana respiration and ripening during storage, offering an effective method for banana preservation and ripening.

One-pot co-crystallized hexanal-loaded ZIF-8/quaternized chitosan film for temperature-responsive ethylene inhibition and climacteric fruit preservation

Controlling ethylene production and microbial infection are key factors to prolong the shelf life of climacteric fruit. Herein, a nanocomposite film, hexanal-loaded ZIF-8/CS (HZCF) with “nano-barrier” structure, was developed by a one-pot co-crystallized of ZIF-8 in situ growth on quaternized chitosan (CS) and encapsulation of hexanal into ZIF-8 via microporous adsorption. The resultant film realized the temperature responsive release of hexanal via the steric hindrance and hierarchical pore structure as “nano-barrier”, which can inhibit ethylene production in climacteric fruit on demand. Based on this, the maximum ethylene inhibition rate of HZCF was up to 52.6 %. Meanwhile, the film exhibits excellent antibacterial, mechanical, UV resistance and water retention properties, by virtue of the functional synergy between ZIF-8 and CS. Contributed to the multifunctional features, HZCF prolonged the shelf life of banana and mango for at least 16 days, which is 8 days longer than that of control fruit. More strikingly, HZCF is washable and biodegradable, which is expected to replace non-degradable plastic film. Thus, this study provides a convenient novel approach to simplify the encapsulation of active molecule on metal-organic frameworks (MOFs), develops a packaging material for high-efficient freshness preservation, and helps to alleviate the survival crisis caused by food waste.

Changes in the expression of genes encoding xanthophyl acyltransferases during the postharvest ripening of avocado (Persea americana) fruit.

Avocado fruit is rich in xanthophylls, which have been related to positive effects on human health. Xanthophyl acetyltransferases (XATs) are enzymes catalyzing the esterification of carboxylic acids to the hydroxyl group of the xanthophyll molecule. This esterification is thought to increase the lipophilic nature of the xanthophyll and its stability in a lipophilic environment. Studies on XATs in fruits are very scarce, and no studies had been carried out in avocado fruit during postharvest. The objective of this work was to investigate the changes in the expression of genes encoding XAT, during avocado fruit ripening. Avocado fruits were obtained from a local market and stored at 15 °C for 8 days. The fruit respiration rate, ethylene production, and fruit peel's color space parameters (L*, a*, b*) were measured during storage. Fruit mesocarp samples were taken after 1, 3, 5, and 7 days of storage and frozen with liquid nitrogen. Total RNA was extracted from fruit mesocarp, and the quantification of the two genes designated as COGE_ID: 936743791 and COGE_ID: 936800185 encoding XATs was performed with real-time quantitative reverse transcription polymerase chain reaction using actin as a reference gene. The presence of a climacteric peak and large changes in color were recorded during postharvest. The two genes studied showed a large expression after 3 days of fruit storage. We conclude that during the last stages of ripening in avocado fruit there was an active esterification of xanthophylls with carboxylic acids, which suggests the presence of esterified xanthophylls in the fruit mesocarp. © 2024 Society of Chemical Industry.

Functional mechanism study of the allelochemical myrigalone A identifies a group of ultrapotent inhibitors of ethylene biosynthesis in plants

Allelochemicals represent a class of natural products released by plants as root, leaf, and fruit exudates that interfere with the growth and survival of neighboring plants. Understanding how allelochemicals function to regulate plant responses may provide valuable new approaches to better control plant function. One such allelochemical, Myrigalone A (MyA) produced by Myrica gale, inhibits seed germination and seedling growth through an unknown mechanism. Here, we investigate MyA using the tractable model Dictyostelium discoideum and reveal that its activity depends on the conserved homolog of the plant ethylene synthesis protein 1-aminocyclopropane-1-carboxylic acid oxidase (ACO). Furthermore, in silico modeling predicts the direct binding of MyA to ACO within the catalytic pocket. In D. discoideum, ablation of ACO mimics the MyA-dependent developmental delay, which is partially restored by exogenous ethylene, and MyA reduces ethylene production. In Arabidopsis thaliana, MyA treatment delays seed germination, and this effect is rescued by exogenous ethylene. It also mimics the effect of established ACO inhibitors on root and hypocotyl extension, blocks ethylene-dependent root hair production, and reduces ethylene production. Finally, in silico binding analyses identify a range of highly potent ethylene inhibitors that block ethylene-dependent response and reduce ethylene production in Arabidopsis. Thus, we demonstrate a molecular mechanism by which the allelochemical MyA reduces ethylene biosynthesis and identify a range of ultrapotent inhibitors of ethylene-regulated responses.

Technical, Environmental, and Economic Analysis Comparing Low-Carbon Industrial Process Heat Options in U.S. Poly(vinyl chloride) and Ethylene Manufacturing Facilities.

Electrification and clean hydrogen are promising low-carbon options for decarbonizing industrial process heat, which is an essential target for reducing sector-wide emissions. However, industrial processes with heat demand vary significantly across industries in terms of temperature requirements, capacities, and equipment, making it challenging to determine applications for low-carbon technologies that are technically and economically feasible. In this analysis, we develop a framework for evaluating life cycle emissions, water use, and cost impacts of electric and clean hydrogen process heat technologies and apply it in several case studies for plastics and petrochemical manufacturing industries in the United States. Our results show that industrial heat pumps could reduce emissions by 12-17% in a typical poly(vinyl chloride) (PVC) facility in certain locations currently, compared to conventional natural gas combustion, and that other electric technologies in PVC and ethylene production could reduce emissions by nearly 90% with a sufficiently decarbonized electric grid. Life cycle water use increases significantly in all low-carbon technology cases. The levelized cost of heat of viable low-carbon technologies ranges from 15 to 100% higher than conventional heating systems, primarily due to energy costs. We discuss results in the context of relevant policies that could be useful to manufacturing facilities and policymakers for aiding the transition to low-carbon process heat technologies.