Ethylene Action Research Articles

The role of modified manganese perovskite oxide for selective oxidative dehydrogenation of ethane: Not only selective H2 combustion but also ethane activation

To break through the thermodynamic reaction limitation of ethane dehydrogenation to ethylene, the oxidative dehydrogenation in the presence of O2 and chemical looping oxidative dehydrogenation has been investigated with the oxygen storage oxide compound. LaMnO3 perovskite catalysts with large specific surface areas were prepared using citric acid-nitrate combustion. The oxygen vacancies and M4+ contents in the catalysts were improved by doping LaMnO3 as the active sites. The experimental results show that the catalyst not only promotes ethane dehydrogenation through selective hydrogen combustion but also promotes ethane conversion through activation of CH. The catalyst exhibits good stability in oxidative dehydrogenation reaction.

Silver nitrate reduces hyperhydricity in shoots regenerated from the hypocotyl of snapdragon cv. Maryland Apple Blossom

We developed an efficient protocol for shoot regeneration from hypocotyl explants in snapdragon (Antirrhinum majus L.) cv. Maryand Apple Blossom by plant growth regulators (PGRs), followed by ethylene synthesis inhibitor Aminoethoxyvinylglycine (AVG), ethylene precursor 1-Aminocyclopropane-1-carboxylate (ACC), and ethylene action inhibitor silver nitrate (AgNO3). The combination of benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D) did not induce shoots, whereas naphthaleneacetic acid (NAA) and Zeatin (Zt) induced shoots. The combination of 0.05 mg/L NAA and 2.5 mg/L Zt resulted in the maximum shoot regeneration percentage and a reasonable number of shoots per explant. However, the regenerated shoots exhibited hyperhydricity and failed to develop into normal plants when introduced into plant growth media. Addition of ACC and AVG to the media containing 0.05 mg/L NAA and 2.5 mg/L Zt inhibited shoot regeneration, while AgNO3 (2.0 mg/L) marginally improved shoot regeneration and successfully reduced hyperhydricity. Shoots grown in AgNO3-containing media showed a reduction in ethylene related gene expression and reactive oxygen species (ROS) accumulation; the leaves showed reduced intercellular space as well as an increase in the number of open stomata under AgNO3 treatment. Moreover, shoots regenerated from AgNO3-containing media easily developed into normal plants in plant growth medium. This study highlights the importance of specific PGRs in shoot regeneration, as well as the role of AgNO3 in reducing the hyperhydricity of shoots regenerated in vitro. These findings will contribute to a better understanding of the hyperhydricity mechanism. We expect this protocol to be useful for in vitro shoot regeneration and genetic transformation of the snapdragon cultivar used in this study.

Manipulation of Senescence of Plants to Improve Biotic Stress Resistance

The physiological state, i.e., senescence or juvenility, of plants and plant organs can have strong effect on their reactions to pathogen attacks. This effect is mainly expressed as changes in the severity of disease symptoms. Generally, necrotrophic pathogens cause more severe symptoms on senescent than on juvenile plants, while biotrophs prefer juvenile tissues. Several factors of senescence have opposite effect on the two pathogen groups, such as decreased photosynthesis, decreased antioxidant capacity, remobilization of nutrients, changes in plant hormonal network, and in fluidity of cell membranes. Furthermore, senescent tissues are less tolerant to toxins and to cell-wall-degrading enzymes. On the other hand, pathogen infection itself has significant effect on the physiology of plants depending on the lifestyle of the pathogen and on the compatibility or incompatibility of the interaction with the plant. There are several possibilities to manipulate the physiological state of plants in order to improve their biotic and abiotic stress tolerance, such as removal of the terminal bud or high doses of nitrogen, external application of cytokinins or of inhibitors of ethylene action, as well as by spontaneous or directed mutation, in vitro selection, or manipulation by various transgenic approach. Even application of mycorrhiza can inhibit the senescence process of plants and improve their tolerance to stresses.

Cobalt-Molybdenum Oxides for Effective Coupling of Ethane Activation and Carbon Dioxide Reduction Catalysis

This study reports the discovery of CoMoOx moieties with synergistic catalytic roles in C2H6–CO2 catalysis. C2H6–CO2 catalysis occurs through multiple, concomitant catalytic cycles, initiated by the dual cycles of C2H6 activation and CO2 activation, together with an undesired coke deposition cycle. C2H6 activation requires reactive oxygen species that assist with the kinetically relevant C–H bond activation; these oxygen species are generated from the CO2 activation cycle within the reverse water-gas shift (RWGS) reaction. An efficient CO2 activation in the RWGS reaction would retain higher O contents in CoMoOx moieties, leading to more effective kinetically relevant C–H bond activation of C2H6 and oxidation of coke precursors and thus increasing turnovers while mitigating deactivation. This mechanistic insight led us to design CoMoOx moieties, where the Co cation acts as a Lewis acid. Together with a vicinal oxygen vacancy, the Co cation activates CO2 via a Vacancy route through the formation of a kinetically relevant [Co···C(O) ═ O··· □vacancy···Mo]‡ transition state, at which the Co interacts with the C and the oxygen vacancy (□vacancy) abstracts the leaving O of CO2. The kinetically coupled cycles lead the ethane conversion rates in dehydrogenation and reforming reactions to both depend directly on the RWGS reaction rates. This mechanistic understanding of rate coupling has led to the design of CoMoOx moieties with dual functionality for effective C2H6–CO2 catalysis.

Design of aminoethoxyvinylglycine functional analogues to delay postharvest ripening of tomato fruit

Ethylene is a key hormone in regulating fruit ripening, thus inhibiting ethylene production is an effective way to delay postharvest ripening of fruit. Aminoethoxyvinylglycine (AVG) is a competitively ethylene synthesis inhibitor that can significantly delay the fruit softening at postharvest stage and prolong the fruit shelf life. However, the high production cost of AVG limits its widespread use. In this study, nine AVG analogues with simple structures were designed and synthesized based on the 1-aminocyclo-propane-1-carboxylic acid synthase (ACS) enzyme ACS2 (Protein Data Bank ID: 1AIY) of tomato. The molecular docking analysis of ACS2 with AVG analogues showed that the compounds 2i, 2k, and 2 n have higher predicted binding activity than the other analogues, which form hydrogen bonds with the key amino acids Ala54 and Arg412 of ACS2. Compounds 2i, 2k, and 2 n reduce ethylene production and delay the postharvest ripening of tomato fruit in varying degrees, and 2 n is the most effective AVG analogue, suggesting that the function of these analogues is basically associated with their predicted binding activity with ACS2. This study developed a new class of ethylene synthesis inhibitors with significant effects on the control of ethylene action and prolonging fruit shelf life. This work also has crucial implications for research on structure-activity relationship and development of more potential AVG functional analogues.

Delaying ripening using 1-MCP reveals chilling injury symptom development at the putative chilling threshold temperature for mature green banana.

Storage at the putative chilling threshold temperature (CTT) to avoid chilling injury still limits postharvest handling of tropical fruit like banana in that ripening may occur at the CTT. To determine whether chilling injury (CI) symptoms would develop in mature green (MG) banana fruit if the CTT exposure was extended by inhibiting ethylene action and thus ripening, 1-methylcyclopropene (1-MCP) was applied. Individual ‘fingers’ from multiple ‘clusters’ of MG bananas were either immersed in water or 50 μg L−1 1-MCP (a.i.) solution and each treatment was divided into three subgroups for storage at 5.0°C (severe CI), 13.0°C (mild CI), or 14.0°C (CTT) ± 0.1°C. 1-MCP delayed ripening in terms of color change for 10 days for fruit stored at the CTT. Ethylene production by fruit at 5.0°C remained around 0.04 ng kg−1 s−1 with no obvious increase during 31-day storage. Ethylene production at 14.0°C (−1-MCP/+1-MCP) increased on Day 33 while increasing on Day 38 for 13.0°C fruit without 1-MCP and on Day 39 for fruit with 1-MCP. Peak climacteric ethylene occurred on Days 44 and 39 for 13.0 and 14.0°C fruit without 1-MCP, respectively, and on Days 59 and 51 for 13.0°C and 14.0°C 1-MCP-treated fruit, respectively. As hypothesized, longer exposure of MG banana fruit to the CTT of 14.0°C without onset of ripening as was allowed by prior 1-MCP treatment allowed CI to develop at that normally non-chilling temperature. Vascular browning was the first visual and most sensitive CI symptom in the experiment and was observed on Day 4 at 5.0°C, Day 10 at 13.0°C, Day 19 at 14.0°C without 1-MCP, and on Day 28 at 14.0°C with 1-MCP. Using a 1-MCP pre-treatment to remove the influence of ethylene from bananas stored at 13°C or 14°C also resulted in slight reduction in vascular browning severity. In conclusion, a putative safe temperature may become a CI temperature if the shelf-life-limiting factor is removed, allowing longer exposure. Chilling at the CTT caused relatively mild injury on fruit, and vascular browning is a sensitive indicator of CI status, while the light-adapted quantum yield of photosystem II [Y(II)] could be a non-destructive indicator of early CI stress in MG banana. Fruit at 13.0/14.0°C developed CI symptoms slightly later with 1-MCP than without 1-MCP. This suggests that ethylene might be involved in early CI symptom development.

The physiological and transcriptomic study of secondary growth in Neolamarckia cadamba stimulated by the ethylene precursor ACC

Though many biological roles of ethylene have been investigated intensively, the molecular mechanism of ethylene's action in woody plants remains unclear. In this study, we investigated the effects of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, on the growth of Neolamarckia cadamba seedlings, a fast-growing tropical tree. After 14 days of ACC treatment, the plants showed a reduced physiological morphology while stem diameter increased; however, this did not occur after the addition of 1-MCP. Meanwhile, the lignin content of N. cadamba also increased. Transcriptome analysis revealed that the expression of the ethylene biosynthesis and signaling genes ACC oxidase (ACO) and ethylene insensitive 3 (EIN3) were up-regulated mainly at the 6th hour and the 3rd day of the ACC treatment, respectively. The transcription levels of transcription factors, mainly in the basic helix-loop-helix (bHLH), ethylene response factor (ERF), WRKY and v-myb avian myeloblastosis viral oncogene homolog (MYB) families, involved in the ethylene signaling and secondary growth also increased significantly. Furthermore, in accordance to the increased lignification of the stem, the transcriptional level of key enzymes in the phenylalanine pathway were elevated after the ACC treatment. Our results revealed the physiological and molecular mechanisms underlying the secondary growth stimulated by exogenous ACC treatment on N. cadamba seedlings.

Main-Group Catalysts with Atomically Dispersed In Sites for Highly Efficient Oxidative Dehydrogenation

Transition metal oxides are well-known catalysts for oxidative dehydrogenation thanks to their excellent ability to activate alkanes. However, they suffer from an inferior alkene yield due to the trade-off between the conversion and selectivity induced by more reactive alkenes than alkanes, which obscures the optimization of catalysts. Herein, we attempt to overcome this challenge by activating a selective main-group indium oxide considered to be inactive for oxidative dehydrogenation in conventional wisdom. Atomically dispersed In sites with the local structure of [InOH]2+ anchored by substituting the protons of supercages in HY are enclosed to be active centers that enable the activation of ethane with a metal-normalized turnover number of almost one magnitude higher than those of their supported In2O3 counterparts. Furthermore, the structure of isolated [InOH]2+ sites could be stabilized by in situ formed H2O from the selective oxidation of hydrogen by In2O3 nanoparticles. As a result, the as-designed main-group In catalysts exhibit 80% ethene selectivity at 80% ethane conversion, thus achieving 60% ethene yield due to active isolated [InOH]2+ sites and selective In2O3 nanoparticles, outperforming state-of-the-art transition metal oxide catalysts. This study unlocks new opportunities for the utilization of main-group elements and could pave the way toward a more rational design of catalysts for highly efficient selective oxidation catalysis.

Polyamines and ethylene action blocker (STS) effectively augment longevity and postharvest attributes in isolated flowers of Digitalis purpurea L.

The present investigation focused on the study of the exogenous inclusion of anti-senescence biogenic polyamines (putrescine, spermidine and spermine) and ethylene antagonist silver thiosulphate on flower longevity and postharvest performance in excised flowers of Digitalis purpurea L. At one day before anthesis stage, isolated buds of Digitalis purpurea were transported to the laboratory in distilled water. The samples were divided into five sets with one set of flower buds (i.e., control) held in distilled water. The remaining four sets were respectively supplied with 0.5, 1 and 1.5 mM of putrescine (PUT), 0.1, 0.2 and 0.3 mM of spermidine (SPD), 0.2, 0.4 and 0.6 mM of spermine (SPM), 0.1, 0.2 and 0.3 mM of silver thiosulphate (STS). The inclusion of polyamines and STS in holding solutions enhanced the flower longevity of D. purpurea significantly compared to the control. The results indicated that the flower longevity of 14 days was recorded in 0.4 mM of spermine, followed by 13 days in 1 mM PUT, 12.5 days in 0.2 mM SPD and 12 days in 0.2 mM STS. This enhanced flower longevity corroborated with the higher values of soluble proteins, total sugars, floral diameter and membrane stability index. The improved flower longevity was also found to be positively associated with increased activities of various antioxidant enzymes viz., superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) and reduced activity of lipoxygenase (LOX). The flowers supplemented with different treatments retained a lower phenolic content than the control. This research concluded that polyamines and STS have a profound impact on the flower longevity of Digitalis flowers. SPM was found to be a more potential polyamine in augmenting the postharvest performance in isolated flowers of D. purpurea.

Kinetic Origins of High Selectivity of Metal Phosphides for Ethane Dehydrogenation

Supercell density functional theory (DFT) calculations are used to create and exercise complete ethane dehydrogenation (EDH) reaction networks over Ni(111) and Ni2P(001). EDH intermediates are predicted to be more weakly bound to Ni2P than to Ni, with the differences being the greatest for deeply dehydrogenated intermediates. Both C–H and C–C bond cleavage activation energies are generally greater on Ni2P than Ni. The implications of these differences are explored through microkinetic models that incorporate a pathway for carbon growth. Ethylene formation rates and selectivities are predicted to be greater over Ni2P than Ni across a wide range of temperatures. Ni is predicted to be more susceptible to coke generation. Ethane activation exerts the greatest degree of rate control on both materials; in contrast, the competition between ethylene desorption and dehydrogenation controls selectivity on Ni, while no single step dominates selectivity on Ni2P. Results are consistent with previously reported observations, highlight the distinct and active contributions of phosphorus to phosphide surface chemistry, and highlight the role of coking pathways on predicted kinetics.

Oxidative co-dehydrogenation of ethane and propane over h-BN as an effective means for C–H bond activation and mechanistic investigations

Hexagonal boron nitride (h-BN) is a highly selective catalyst for oxidative dehydrogenation of light alkanes to produce the corresponding alkenes. Despite intense recent research effort, many aspects of the reaction mechanism, such as the observed supra-linear reaction order of alkanes, remain unresolved. In this work, we show that the introduction of a low concentration of propane in the feed of ethane oxidative dehydrogenation is able to enhance the C2H6 conversion by 47%, indicating a shared reaction intermediate in the activation of ethane and propane. The higher activity of propane makes it the dominant radical generator in the oxidative co-dehydrogenation of ethane and propane (ODEP). This unique feature of the ODEP renders propane an effective probe molecule to deconvolute the two roles of alkanes in the dehydrogenation chemistry, i.e., radical generator and substrate. Kinetic studies indicate that both the radical generation and the dehydrogenation pathways exhibit a first order kinetics toward the alkane partial pressure, leading to the observed second order kinetics of the overall oxidative dehydrogenation rate. With the steady-state approximation, a radical chain reaction mechanism capable of rationalizing observed reaction behaviors is proposed based on these insights. This work demonstrates the potential of ODEP as a strategy of both activating light alkanes in oxidative dehydrogenation on BN and mechanistic investigations.

Evaluation of ethylene mutant snapdragon lines for rooting, gravitropism, 1-MCP, ethylene, and vase-life responses

This study was undertaken to assess morphological characteristics of rooting, gravitropism, floral fitness, ethylene tolerance, and vase-life of 16 ethylene mutants of snapdragon, generated via seed mutagenesis of the inbred line OAK564 with ethyl methanesulfonate (EMS). This included screening of seedlings of ethylene mutant lines for rooting response following challenge by different levels of 1-aminocyclopropane-1-carboxylate (ACC), gravitropic response of seedlings and mature flowering spikes, seedling response following treatment of greenhouse plants with ethylene, as well as challenge of mature flowering spikes with ethylene along with and without an application of 1-methylcyclopropene (1-MCP), a known inhibitor of ethylene action, as well as vase-life evaluations of mature flowering spikes. These mutant lines displayed varied responses for all treatments, with some lines exhibiting enhanced rooting, gravitropism, floral fitness, ethylene tolerance, and longer vase-life than the inbred control OAK564. For all evaluations, these mutants exhibited genetic variability for these various traits; thus, offering opportunities for further breeding efforts to improve these important economic traits in cut snapdragon.

Ethylene Suppresses Abscisic Acid, Modulates Antioxidant System to Counteract Arsenic-Inhibited Photosynthetic Performance in the Presence of Selenium in Mustard

Arsenic (As) stress provokes various toxic effects in plants that disturbs its photosynthetic potential and hampers growth. Ethylene and selenium (Se) have shown regulatory interaction in plants for metal tolerance; however, their synergism in As tolerance through modification of the antioxidant enzymes and hormone biosynthesis needs further elaboration. With this in view, we investigated the impact of ethylene and Se in the protection of photosynthetic performance against As stress in mustard (Brassica juncea L.). Supplementation with ethephon (2-chloroethylphosphonic acid; ethylene source) and/or Se allayed the negative impact of As-induced toxicity by limiting As content in leaves, enhancing the antioxidant defense system, and decreasing the accumulation of abscisic acid (ABA). Ethylene plus Se more prominently regulated stomatal behavior, improved photosynthetic capacity, and mitigated As-induced effects. Ethephon in the presence of Se decreased stress ethylene formation and ABA accumulation under As stress, resulting in improved photosynthesis and growth through enhanced reduced glutathione (GSH) synthesis, which in turn reduced the oxidative stress. In both As-stressed and non-stressed plants treated with ethylene action inhibitor, norbornadiene, resulted in increased ABA and oxidative stress with reduced photosynthetic activity by downregulating expression of ascorbate peroxidase and glutathione reductase, suggesting the involvement of ethylene in the reversal of As-induced toxicity. These findings suggest that ethephon and Se induce regulatory interaction between ethylene, ABA accumulation, and GSH metabolism through regulating the activity and expression of antioxidant enzymes. Thus, in an economically important crop (mustard), the severity of As stress could be reduced through the supplementation of both ethylene and Se that coordinate for maximum stress alleviation.

Promoted MoxCy‐based Catalysts for the CO2 Oxidative Dehydrogenation of Ethane

AbstractThe CO2 oxidative dehydrogenation reaction has the potential to play a role in the advancement of CO2‐utilizing catalytic reactions, co‐activating CO2 and short‐chained alkanes. Transition metal carbides are promising catalysts for this reaction, in particular MoxCy, however catalytic stability is a major challenge. In this study, the addition of a promoter (Fe, K, Ni or Pt) has shown to significantly influence the crystal structure of the carbide system as well as the acid‐base characteristics. K promotion decreased the number of acid sites, limiting ethane activation and the removal of the oxygen surface species formed in CO2 activation. The catalysts deactivate due to oxidation to MoOx. Fe decreased the initial activity, but it increased the stability of the oxygen surface species, which enhanced the stability of the catalyst and ethylene selectivity to outperform the unpromoted sample. Oxidation of the carbide and carbon deposition during the reaction could not be prevented. Ni promotion increases the number of basic sites, enhancing the CO2 activation, shown by the highest activity obtained during the reverse water‐gas‐shift experiments. At higher CO2 content in the feed the dry‐reforming reaction becomes the dominant reaction pathway. Pt suppressed the dry‐reforming reaction, but instead increased the direct dehydrogenation activity, accompanied by a high degree of carbon deposition. No oxidation to MoOx was observed at a stoichiometric CO2 to C2H6 feed ratio.

Ethylene and abscisic acid play a key role in modulating apple ripening after harvest and after cold-storage

An autocatalytic burst in ethylene production generally accompanies ripening of detached apple fruit. However, if apples are left to ripen attached to the tree, some cultivars, will not experience this autocatalytic ethylene production and the fruit will never acquire the organoleptic properties of detached ripened fruit. Accordingly, the present study aimed to understand how the hormonal crosstalk regulates ripening in ‘Golden Reinders’ apples, ripened on-tree, detached from the tree or after a period of cold storage, following the commercial harvest date. Our results showed that during on-tree ripening, ethylene production remained low, and no significant changes were observed in fruit colour or firmness. In fruit ripened detached from the tree, ethylene production was preceded by an increase of indole 3-acetic acid (IAA) and gibberellic acid (GA3) levels, whereas a cold-induced accumulation of jasmonic acid (JA) seemed to induce an earlier initiation of the climacteric burst in fruit ripened after cold storage. In both postharvest conditions, the accumulation of abscisic acid (ABA) may be either needed or facilitating the action of ethylene on triggering some ripening-related changes, pointing out the importance of both hormones in mediating apple ripening. In contrast, changes in sugars and ROS/antioxidants did not vary among the different ripening scenarios suggesting that none of the measured compounds may act as signalling molecules during apple ripening. Collectively, our results highlight that ethylene together with ABA played a crucial role in triggering ripening-related changes during postharvest ripening of ‘Golden Reinders’ apples.

Postharvest quality of 'Cripps Pink' apple fruit influenced by ethylene antagonists during controlled atmosphere storage with photocatalytic oxidation.

BACKGROUNDThe present study investigated the efficacy of 1H‐cyclopropa[b]naphthalene (NC) and 1H‐cyclopropabenzene (BC) with respect to antagonizing ethylene action and maintaining postharvest fruit quality in ‘Cripps Pink’ apple stored in a controlled atmosphere comprising 3.45 ± 0.45% oxygen and 2.40 ± 0.36% carbon dioxide with photocatalytic oxidation (PCO) at 0 ± 1 °C and 90 ± 5% relative humidity.RESULTSThe BC, NC, and 1‐methylcyclopropene (1‐MCP) fumigation treatments delayed the climacteric peaks onset and retarded ethylene production rates compared to control fruit. Treatments with ethylene antagonist also maintained fruit firmness (up to 1.12 times), titratable acidity (up to 1.08 times), malic acid (up to 1.23 times), ascorbic acid (up to 1.12 times) and total phenol levels (up to 1.19 times) higher compared to that in control fruit. The 1‐MCP was more efficient in reducing the rates of ethylene production compared to NC and BC, but, in the case of all other fruit quality parameters investigated, the effect of NC and BC treatments were on a par with 1‐MCP.CONCLUSIONThe NC and BC have the potential to be used as ethylene antagonists in ‘Cripps Pink’ apple fruit stored in a controlled atmosphere with PCO. The efficacy of different concentrations of NC and BC in downregulating ethylene action, as well as interactive effects of PCO on the performance of ethylene antagonists, still warrants further investigation. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Boosting Polyamines to Enhance Shoot Regeneration in Potato (Solanum tuberosum L.) Using AgNO3

Advancements in shoot regeneration systems support biotechnology-based tools used in the genetic improvement of plant crops. This study aims to enhance shoot regeneration in potatoes by boosting polyamine content by adding AgNO3 to the shoot regeneration medium (MS medium supplemented with 30 g L−1 sucrose, 100 mg L−1 myoinositol, and 2.25 BA mg L−1). Five concentrations of AgNO3 (2, 4, 6, 8, and 10 mg L−1) were used in addition to a control. The effect of AgNO3 on regeneration assumed a more or less concentration-dependent bell-shaped curve peaking at 4 mg L−1. Enhancements in shoot regeneration were attributed to the known role of AgNO3 as an ethylene action blocker in addition to improvements in polyamine accumulation without an increase in H2O2 content, lipid peroxidation, or DNA damage. The uncoupling of shoot regeneration and polyamine content recorded at high AgNO3 concentrations can be attributed to the consumption of polyamines to counteract the synchronized oxidative stress manifested by increases in H2O2 content, lipid peroxidation, and DNA damage.

Effects of 1-methylcyclopropene (1-MCP) treatment on ethanol fermentation of Nanguo pear fruit during ripening.

The aim of this study was to analyze the effects of 1-methylcyclopropene (1-MCP) on ethanol fermentation of Nanguo pears during ripening. Pears were exposed to 1µl/L 1-MCP and stored at 20±2°C. Our data indicated that postharvest application of 1-MCP maintained flesh firmness and reduced ethylene production and respiration rate during storage compared with untreated fruits. 1-MCP treatment delayed the second glucose peak during fruit ripening. The contents of pyruvate and acetyl-CoA were generally reduced by 1-MCP treatment, and at the same time, their peaks were delayed by it during storage compared with controls. The contents of citric acid (CA) and oxaloacetate (OA) were increased by 1-MCP, whereas the contents of acetaldehyde and ethanol were reduced during the whole storage period compared with controls. Activities of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) were reduced by application of 1-MCP during the early stage of storage, and the appearance of their peak activities was also delayed after treatment with 1-MCP. These data showed that postharvest application of 1-MCP could effectively delay the production of the "alcohol taste" of Nanguo pears during ripening. PRACTICAL APPLICATIONS: Nanguo pear is one of the most common cultivars that widely grow in northeast China. It is preferred by many consumers for its unique "alcohol taste", which is mainly produced through ethanol fermentation during ripening. Until now, the mechanisms for regulating ethanol fermentation in ripening Nanguo pears are still unclear. Our data indicated that postharvest application of the ethylene action inhibitor 1-MCP could effectively delay the production of the "alcohol taste" of Nanguo pears during ripening. The data from this study can provide reference data for maintaining the quality of postharvest Nanguo pears.

ERF Transcription Factor OsBIERF3 Positively Contributes to Immunity against Fungal and Bacterial Diseases but Negatively Regulates Cold Tolerance in Rice.

We previously showed that overexpression of the rice ERF transcription factor gene OsBIERF3 in tobacco increased resistance against different pathogens. Here, we report the function of OsBIERF3 in rice immunity and abiotic stress tolerance. Expression of OsBIERF3 was induced by Xanthomonas oryzae pv. oryzae, hormones (e.g., salicylic acid, methyl jasmonate, 1-aminocyclopropane-1-carboxylic acid, and abscisic acid), and abiotic stress (e.g., drought, salt and cold stress). OsBIERF3 has transcriptional activation activity that depends on its C-terminal region. The OsBIERF3-overexpressing (OsBIERF3-OE) plants exhibited increased resistance while OsBIERF3-suppressed (OsBIERF3-Ri) plants displayed decreased resistance to Magnaporthe oryzae and X. oryzae pv. oryzae. A set of genes including those for PRs and MAPK kinases were up-regulated in OsBIERF3-OE plants. Cell wall biosynthetic enzyme genes were up-regulated in OsBIERF3-OE plants but down-regulated in OsBIERF3-Ri plants; accordingly, cell walls became thicker in OsBIERF3-OE plants but thinner in OsBIERF3-Ri plants than WT plants. The OsBIERF3-OE plants attenuated while OsBIERF3-Ri plants enhanced cold tolerance, accompanied by altered expression of cold-responsive genes and proline accumulation. Exogenous abscisic acid and 1-aminocyclopropane-1-carboxylic acid, a precursor of ethylene biosynthesis, restored the attenuated cold tolerance in OsBIERF3-OE plants while exogenous AgNO3, an inhibitor of ethylene action, significantly suppressed the enhanced cold tolerance in OsBIERF3-Ri plants. These data demonstrate that OsBIERF3 positively contributes to immunity against M. oryzae and X. oryzae pv. oryzae but negatively regulates cold stress tolerance in rice.

The Role of Modified Manganese Perovskite Oxide for Selective Oxidative Dehydrogenation of Ethane: Not Only Selective H2 Combustion But Also Ethane Activation

The Role of Modified Manganese Perovskite Oxide for Selective Oxidative Dehydrogenation of Ethane: Not Only Selective H2 Combustion But Also Ethane Activation