Use Of Ethylene Research Articles

Green electrosynthesis of bis(indolyl)methane derivatives in deep eutectic solvents

In this study, a new green method was developed for the synthesis of bis(indolyl)methane derivatives using electrochemical bisarylation reaction in deep eutectic solvents as a green alternative to traditional solvents and electrolytes. The effects of varying time, current, type of solvent and material of electrodes were all studied. The optimum reaction conditions involved the use of ethylene glycol/choline chloride with a ratio of 2:1 at 80 °C for 45 min. Graphite and platinum were used as cathode and anode, respectively. The newly developed method offered many advantages such as using mild reaction conditions, short reaction time and affording high product yields with a wide range of substituted aromatic aldehydes bearing electron donating or electron withdrawing substituents. In addition, the electrochemical method proved to be more effective than heating in deep eutectic solvents and afforded higher yields of products in shorter reaction time. The mechanism of the electrochemical reaction was proposed and confirmed using the cyclic voltammetry study.

The effect of the ethylene phytohormone on the growth, development and yield of potatoes

. In 2021–2022, experiment on growing potatoes with preliminary seed tubers storage in the environment of the ethylene phytohormone was conducted at the Russian Potato Research Centre. The aim of the research was to determine the influence of seed tubers treatment with phytohormone ethylene on growth, development and yield of potatoes, taking into account the preplant doses of mineral fertilizers and variety specificities. Ethylene appliance at a concentration of 15 ml/m3 was carried out in the potato storage from November till the end of April at a temperature 4 0C and a relative humidity 90-95%. As a result of research, it was found that the use of ethylene while seed potatoes storing of varieties Grand and Vympel provided the 2-3 days earlier emergence of seedlings; an increase in plant height by 1.5-12.4%; an increase in number of stems per plant by 11.4-26.3%; an increase in leaf surface area by 5.5-11.3%. The total potato yield due to ethylene appliance increased by 5.6-12.9% or 1.3-1.8 t/ha (Grand) and by 5.6-27.7% or 1.1-3.6 t/ha (Vympel). The most significant increase of yield was noted when growing potatoes with mineral fertilizers dose N30P30K45. Ethylene seed treatment did not have a significant effect on the percentage of commercial tubers. The Grand variety, compared with the Vympel, turned out to be more responsive to the use of high doses of mineral fertilizers. It was found that the most significant factor that provided an increase in total yield by 4.2-12.4 t/ha or by 25.3-93.9% (depending on the variety and ethylene treatment) was the dose of fertilizers.

Evaluation of harvest yield and beverage quality of coffee under ethylene application

The coffee plant is characterized by the irregular ripening of its fruits. This uneven ripening often makes it impossible to optimize its harvest, since green fruits are more adhered to the plant than those in the ripe and overripe stages. In addition, it can influence the final product’s beverage quality. The use of ethylene is an alternative to optimize and increase the harvest yield of coffee, besides reducing expenditures on labor and post-harvest ground picking. This study was carried out to examine the harvest yield of coffee variety Mundo Novo IAC 379/19 under different ethylene rates as well as to analyze beverage quality in the different treatments. The experiment was laid out in a randomized-block design with four treatments (ethylene rates: 0, 300, 500, or 700 mL ha-1). The plots consisted of nine plants and three replications, but only the three central plants were evaluated. Results were analyzed by Tukey’s test at a significance level of 5%. The rates of 700 and 300 mL ha-1 provided the lowest amount of green fruits, whereas the percentage of ripe fruits was equivalent between treatments. The treatment with 700 mL ha-1 resulted in the highest percentage of fruits in the overripe stage, among the evaluated rates. Ethylene use did not increase harvest efficiency. Control treatment provided a significantly higher number of green fruits. Additionally, the use of ethylene-induced changes in the chemical composition of the bean and beverage quality.

Evaluation of Ethylene Usage and Effects of Temperature, Humidity, and Lights on the Ripening of Banana (Musa spp)

Introduction: Banana as a basic food plays an important role in improving food security. This plant has a special value due to its short fruiting time and economic profitability. Banana tree is widely cultivated in developing and tropical countries and is considered one of the most important fruit trees in the world. Banana is climacteric fruits. Most of the fruits are ripened on the tree, but for export we need to harvest and store unripe. The aim of this study is to evaluate the use of ethylene and the effect of different temperatures, humidity and light on the ripening of bananas. Materials and Method: This study was carried out in the laboratory of Sar-e-Pol Higher Education Institute from 7 Nov to 28 Dec 2022, in order to obtain the best conditions for the quick ripening of bananas. Non-scratch bananas were randomly purchased from market. They were separated in pairs and put to the place that was already prepared for testing, and subjected to different treatments and kept for 48 hours in a dark and warm place with a temperature of 18 °C. Findings: The findings of this research show that the bananas treated with ethylene, ripen earlier than the control bananas at different temperatures. The effect of 18 and 22°C temperatures in 3 to 4 days and 24°C temperatures in 1 to 2 days was observed. Bananas that were ripened at a high temperature were sweeter and had less smell than those that were ripened at a lower temperature. Bananas that were kept at a relative humidity of 70 percent and above ripped later than the bananas that were kept at a relative humidity of less than 70 percent. High and low relative humidity has less effect on the inside quality of the banana, but has a direct effect on attractiveness and color. Bananas that were ripened in bright light were sweeter and yellower in color than those in the dark. Conclusion: Based on the findings of this research, the use of chemical substances (ethylene), temperature, humidity and light for the ripening of unripe bananas has a direct effect on its attractiveness and quality.

Ethylene Inhibits Sprouting of Onion Bulbs during Long-term Storage

The protrusion of sprouts is a major cause of loss of dry onions (Allium cepa L.) during extended storage. Sprouting is conventionally suppressed by treating onions with maleic hydrazide (MH) before harvest. More recently, ethylene was reported to inhibit sprout growth in stored onions, but commercial use of ethylene has been limited. Therefore, the objective of this study was to assess the effectiveness of ethylene on sprout suppression of five commercial cultivars of onions during storage and compare its effectiveness with and without MH treatment. Onions treated with MH were stored for up to 9 months at 1 °C in atmospheres with and without ethylene in a series of experiments conducted over six seasons. Differences in sprout elongation and protrusion were observed during storage in air among the five cultivars. Storage in ethylene was effective in inhibiting sprout elongation and root growth of onion bulbs in all cultivars, with concentrations of 7 µL·L−1 ethylene being more effective than 1 µL·L−1 ethylene. Delaying application of ethylene by 4 months was less effective in inhibiting sprout elongation than continuous treatment. Ethylene provided greater sprout suppression than MH treatments alone and could serve as a replacement for MH.

Systematic thermodynamic approach for designing mixed refrigerants used in hydrogen precooling process

Designing an optimal mixed-refrigerant (MR) composition for any cryogenic refrigeration process plays a key role in the process overall performance. However, the existing approaches of developing mixed-refrigerants for these processes are difficult, time-consuming, and semi-random trial and error approaches. Therefore, for the first time, this study presents a systematic thermodynamic approach to optimally design mixed-refrigerants for any cryogenic process. In particular, the developed approach is conducted for the hydrogen precooling process (HPP) with a precooling temperature less than −193 °C. This approach consists of four criteria and seven major steps needed for the development of an energy-efficient HPP. Using this approach, 15 new mixed-refrigerants are created, analyzed, and compared based on the specific energy consumption (SEC) and coefficient of performance of the HPP. Further sensitivity analyses for the major operating conditions of the HPP are conducted for the best five cases. A minimum SEC of 1.03 kWh/khH2Feed at wet-cooling conditions and of 1.32 kWh/khH2Feed at dry-cooling conditions are achieved, which is remarkably 78.81% lower than the SEC of the existing HPP in commercial plants. This study also found that eight-component MR is the best option to create optimal mixtures for cryogenic cooling processes with perfect match between the composite curves of all heat exchangers of the HPP. While methane, nitrogen, and hydrogen components are essential for the MR to achieve energy-efficient HPP, the use of ethylene instead of ethane, H2 instead of neon, and R14 instead of NH3 is recommended to optimize the SEC.

Radical Difunctionalization of Gaseous Ethylene Guided by Quantum Chemical Calculations: Selective Incorporation of Two Molecules of Ethylene

Ethylene, of which about 170 million tons are produced annually worldwide, is a fundamental C2 feedstock that is widely used on an industrial scale for the synthesis of polyethylenes and polyvinylchlorides. Compared to other alkenes, however, the direct use of ethylene for the synthesis of fine chemicals such as pharmaceuticals and agrochemicals is limited, probably due to its small and gaseous character. We, herein, report a new radical difunctionalization strategy of ethylene, aided by quantum chemical calculations. Computationally proposed imidyl and sulfonyl radicals can be introduced into ethylene in the presence of an Ir photocatalyst under irradiation with blue light-emitting diodes (LEDs) (λmax = 440 nm). The present reaction systems led to the selective incorporation of two molecules of ethylene into the substrate, which could be rationally explained by computational analysis.

Influence of 1‐methylcyclopropene (1‐MCP) on ripening and ethylene biosynthesis‐related enzyme gene expression in harvested blueberries

The aim of the study was to discuss the effect of 1-methylcyclopropene (1-MCP) with and without ethylene on physiological indexes and ethylene biosynthesis genes expression in blueberries. Results showed that treatment of 1-MCP alone, or with ethylene, improved firmness, soluble solids content, total phenols content, enzyme activities in comparison with control. Treatment with ethylene promoted respiratory action, decay incidence, and browning index comparing with untreated group. In addition, expression levels of AcACS1 and AcACO1 in 1-MCP-treated samples, or associated with ethylene, decreased for different levels during storage that confirmed 1-MCP contributed to the downregulation of ethylene biosynthesis genes expression. Subsequent use of ethylene did not neutralize the effectiveness of 1-MCP on maintaining commercial quality of blueberries. Practical applications The results of this study were helpful to further understand the regulation mechanism of 1-methylcyclopropene (1-MCP) on ethylene biosynthesis genes, which provided theoretical basis for perfecting the fruit ripening theory and reference for the breakthrough of fruit storage and preservation technology. Further studies were needed to explore the action mechanism of 1-MCP treatment on suppressing ethylene biosynthesis genes expression of blueberry fruits by genomics or proteomics techniques.

Effect of 1‐methylcyclopropene (1‐MCP) on ripening and volatile compounds of blueberry fruit

Blueberry fruit (Vaccinium spp. Berkeley) are popular with people due to the functional components, but they are perishable. The objective of the study was to evaluate the effect of 1-methylcyclopropene (1-MCP) with and without ethylene on ripening and volatile compounds of blueberry fruit. Sensory quality, physicochemical indexes, functional component, antioxidant activity, and principal component analysis of volatile compounds of fruit were detected. The present results indicated that application of ethylene accelerated ethylene production and respiration rate, decreased antioxidant activity and functional components contents of blueberries in comparison with the untreated samples. The degradation effect of ethylene was effectively neutralized by 1-MCP. Treatment of 1-MCP with or without ethylene enhanced firmness, functional components contents, antioxidant activity, and inhibited ethylene production, respiration rate comparing with the control. Furthermore, simultaneous use of ethylene and 1-MCP treatment guaranteed better quality and volatile compounds in blueberry fruit during the whole storage. Practical applications The volatile aroma compounds of blueberries play an important role in enhancing taste. Nevertheless, the use of 1-MCP may reduce the production of aromatic substances, although it can delay the ripening of fruit. Furthermore, consumer difference tests indicated that people can differentiate the 1-MCP-treated apples from the control group. So the commercial application of 1-MCP on fruit is restricted and unfeasible. But a large number of studies on other fruit have shown that combined treatment of 1-MCP and ethylene probably solves this problem. Thus, we tried to apply this method to blueberry fruit, with the purpose of preserving the aroma component while extending shelf life of blueberries.

Site-Selective Catalytic Deaminative Alkylation of Unactivated Olefins.

A catalytic deaminative alkylation of unactivated olefins is described. The protocol is characterized by its mild conditions, wide scope, including the use of ethylene as substrate, and exquisite site-selectivity pattern for both α-olefins and internal olefins, thus unlocking a new catalytic platform to forge sp3-sp3 linkages, even in the context of late-stage functionalization.

Efficacy of Postharvest Technologies on Ripening Behavior and Quality of Banana Varieties Grown in Ethiopia

ABSTRACTBanana is the most important cash and food security crop in Ethiopia. However, the ripening quality and postharvest life of the fruits are not well studied to meet the domestic and international market standards. An experiment was therefore conducted with objectives of describing the ripening behaviors and postharvest qualities of banana varieties and identifying appropriate postharvest technologies for improved ripening and long postharvest life of fruits. The results of the experiment revealed the existence of highly significant variation between banana varieties, ripening temperatures, packaging, and their second- and third-order interactions for length, weight, volume, pulp-to-peel ratio, and pulp diameter. All fruits of the varieties except the local could not ripe well without ripening treatments. Temperatures at 15°C and 20°C were optimum for yellow peel color development. Better eating fruit quality and peel color development were achieved by ripening of fruits at 20°C and 25°C with perforated plastic packaging. Further research on treatments and technologies that can improve the ripening quality and postharvest life of Ethiopian banana like the use of ethylene should be done, and studies on physicochemical changes occurred during fruit maturation and ripening of Ethiopian grown banana varieties in different seasons and agroecologies should also be conducted to reduce the post harvest loss caused by fruit ripening problem.

Trans Arterial Embolization of Non-variceal Upper Gastrointestinal Bleeding: Is the Use of Ethylene–Vinyl Alcohol Copolymer as Safe as Coils?

The safety of liquid embolics over the conventional coils for the treatment of non-variceal upper gastrointestinal bleeding (UGIB) approach is still unclear. Purpose of this study is to assess the safety of ethylene-vinyl alcohol copolymer (EVOH 6%) over coils in the treatment of UGIB. All the upper gastrointestinal tract embolization procedures performed in a single center in a 6-year period were reviewed. Patients embolised with coils (Group A) versus those embolised with EVOH 6% (Group B) were compared. Technical/clinical success, bleeding recurrence, complication and mortality rates were analyzed. A total 71 patients were included in the study (41 Group A and 30 Group B). Coagulopathy was present in 21% of Group A and 46% of Group B patients (p < 0.05). Technical and clinical success was 97.6 and 92.7% for Group A, and 100 and 93.3% for Group B respectively, (p > 0.05). Ten patients (17% Group A; 10% Group B) re-bled within the first 36h and all of them were re-treated successfully with a second embolization. In Group A one major complication (bowel ischemia) occurred. No complication occurred in Group B. The survival rate in the first 30days was 90.3% for group A and 90% for group B (p > 0.05). This study demonstrated EVOH 6% appears to be as safe and effective as coils in the treatment of non-variceal UGIB.

Kinetically E-selective macrocyclic ring-closing metathesis.

Macrocyclic compounds are central to discovery of new drugs but their preparation is often challenging because of the energy barrier required for bringing together and fusing the two ends of an acyclic precursor1. Ring-closing metathesis (RCM) 2,3,4 is a catalytic process that has allowed access to countless biologically active macrocyclic organic molecules even on large scale (up to 200 kilograms)5. The potency of a macrocyclic compound can depend on the stereochemistry of its alkene, or one isomer might be needed for subsequent stereoselective modification (e.g., dihydroxylation6). Still, while kinetically controlled Z-selective RCM reactions have been reported7,8,9,10, the only available olefin metathesis approach for accessing macrocyclic E olefins entails selective removal of the Z component of a stereoisomeric mixture by ethenolysis10, sacrificing substantial quantities of material if E/Z ratios are near unity. Use of ethylene can also cause adventitious olefin isomerization, a particularly serious problem when the E alkene is energetically less favored. Here, we show that dienes containing an E-alkenyl–B(pinacolato) group, widely used in catalytic cross-coupling11, possess the requisite electronic and steric attributes to allow them to be converted stereoselectively to E macrocyclic alkenes. Reactions are promoted by a molybdenum monoaryloxide pyrrolide complex and afford products in up to 73 percent yield and >98:2 E:Z ratio. Utility is highlighted by application to preparation of the twelve-membered ring antibiotic recifeiolide12,13 and the eighteen-membered ring Janus kinase 2/Fms-like tyrosine kinase-3 (JAK2/FLT3) inhibitor pacritinib14,15 the Z isomer of which has lower potency than the E16. The eighteen-membered ring moiety of pacritinib, a potent in vivo anti-cancer agent in advanced clinical trials for treatment of lymphoma and myelofibrosis, was prepared by an RCM carried out at 20 times higher concentration than when a ruthenium carbene was employed (0.02 vs. 0.001 M; 73% yield, 92% E).

From Biomass‐Derived Furans to Aromatics with Ethanol over Zeolite

AbstractWe report a novel catalytic conversion of biomass‐derived furans and alcohols to aromatics over zeolite catalysts. Aromatics are formed via Diels–Alder cycloaddition with ethylene, which is produced in situ from ethanol dehydration. The use of liquid ethanol instead of gaseous ethylene, as the source of dienophile in this one‐pot synthesis, makes the aromatics production much simpler and renewable, circumventing the use of ethylene at high pressure. More importantly, both our experiments and theoretical studies demonstrate that the use of ethanol instead of ethylene, results in significantly higher rates and higher selectivity to aromatics, due to lower activation barriers over the solid acid sites. Synchrotron‐diffraction experiments and proton‐affinity calculations clearly suggest that a preferred protonation of ethanol over the furan is a key step facilitating the Diels–Alder and dehydration reactions in the acid sites of the zeolite.

From Biomass-Derived Furans to Aromatics with Ethanol over Zeolite.

We report a novel catalytic conversion of biomass-derived furans and alcohols to aromatics over zeolite catalysts. Aromatics are formed via Diels-Alder cycloaddition with ethylene, which is produced in situ from ethanol dehydration. The use of liquid ethanol instead of gaseous ethylene, as the source of dienophile in this one-pot synthesis, makes the aromatics production much simpler and renewable, circumventing the use of ethylene at high pressure. More importantly, both our experiments and theoretical studies demonstrate that the use of ethanol instead of ethylene, results in significantly higher rates and higher selectivity to aromatics, due to lower activation barriers over the solid acid sites. Synchrotron-diffraction experiments and proton-affinity calculations clearly suggest that a preferred protonation of ethanol over the furan is a key step facilitating the Diels-Alder and dehydration reactions in the acid sites of the zeolite.

Physiological and proteomic mechanisms of waterlogging priming improves tolerance to waterlogging stress in wheat (Triticum aestivum L.)

Both physiological and proteomic analyses were performed to explore the mechanism of waterlogging priming on plant tolerance to waterlogging stress in wheat. Compared with non-primed plants (CW), waterlogging primed plants (WW) showed higher activity of enzymes in the ascorbate–glutathione cycle. In agreement with the physiological results, proteins associated with energy metabolism and stress defense had a significantly higher expression in WW than CW. In particular, the proteins related to ethylene biosynthesis showed a higher expression in WW than CW. Moreover, exogenous ethephon (EW), ethylene precursor 1-aminocyclopropanecarboxylic acid (ACW) and an ethylene inhibitor amino-oxyacetic acid were applied before waterlogging to ascertain the effects of ethylene on waterlogging. Use of ACW resulted in a higher yield as compared with non-pretreatment with waterlogging stress. A greater yield loss in EW was due to the fact that higher ethylene concentration led to a more severe seed abortion. Use of ethylene alleviated the negative effects on leaf photosynthesis by increasing stomatal conductance under waterlogging stress. In short, priming alleviated the negative effects of waterlogging stress in wheat, and use of exogenous ethylene resulted in an increase in leaf photosynthesis by promoting stomata opening under waterlogging stress.

Comprehensive Proteomics Analysis of Laticifer Latex Reveals New Insights into Ethylene Stimulation of Natural Rubber Production.

Ethylene is a stimulant to increase natural rubber latex. After ethylene application, both fresh yield and dry matter of latex are substantially improved. Moreover, we found that ethylene improves the generation of small rubber particles. However, most genes involved in rubber biosynthesis are inhibited by exogenous ethylene. Therefore, we conducted a proteomics analysis of ethylene-stimulated rubber latex, and identified 287 abundant proteins as well as 143 ethylene responsive latex proteins (ERLPs) with mass spectrometry from the 2-DE and DIGE gels, respectively. In addition, more than 1,600 proteins, including 404 ERLPs, were identified by iTRAQ. Functional classification of ERLPs revealed that enzymes involved in post-translational modification, carbohydrate metabolism, hydrolase activity, and kinase activity were overrepresented. Some enzymes for rubber particle aggregation were inhibited to prolong latex flow, and thus finally improved latex production. Phosphoproteomics analysis identified 59 differential phosphoproteins; notably, specific isoforms of rubber elongation factor and small rubber particle protein that were phosphorylated mainly at serine residues. This post-translational modification and isoform-specific phosphorylation might be important for ethylene-stimulated latex production. These results not only deepen our understanding of the rubber latex proteome but also provide new insights into the use of ethylene to stimulate rubber latex production.

Dehydrogenation of n-Alkanes by Solid-Phase Molecular Pincer-Iridium Catalysts. High Yields of α-Olefin Product.

We report the transfer-dehydrogenation of gas-phase alkanes catalyzed by solid-phase, molecular, pincer-ligated iridium catalysts, using ethylene or propene as hydrogen acceptor. Iridium complexes of sterically unhindered pincer ligands such as (iPr4)PCP, in the solid phase, are found to give extremely high rates and turnover numbers for n-alkane dehydrogenation, and yields of terminal dehydrogenation product (α-olefin) that are much higher than those previously reported for solution-phase experiments. These results are explained by mechanistic studies and DFT calculations which jointly lead to the conclusion that olefin isomerization, which limits yields of α-olefin from pincer-Ir catalyzed alkane dehydrogenation, proceeds via two mechanistically distinct pathways in the case of ((iPr4)PCP)Ir. The more conventional pathway involves 2,1-insertion of the α-olefin into an Ir-H bond of ((iPr4)PCP)IrH2, followed by 3,2-β-H elimination. The use of ethylene as hydrogen acceptor, or high pressures of propene, precludes this pathway by rapid hydrogenation of these small olefins by the dihydride. The second isomerization pathway proceeds via α-olefin C-H addition to (pincer)Ir to give an allyl intermediate as was previously reported for ((tBu4)PCP)Ir. The improved understanding of the factors controlling rates and selectivity has led to solution-phase systems that afford improved yields of α-olefin, and provides a framework required for the future development of more active and selective catalytic systems.

Effects of use of coupling agents on the properties of microfibrillar composite based on high-density polyethylene and polyamide-6

Microfibrillar composites from high-density polyethylene (HDPE-75 wt%) and polyamide-6 (PA6-25 wt%) were made through a reactive extrusion at the processing temperature of PA6 in combination with hot stretching to form microfibrillar composites, and injection molding at the melt temperature of HDPE to form final composites. The scanning electron microscope observations demonstrated the formation of the PA6 microfibers during extrusion. Incorporation of PA6 microfibers led to an improvement in both flexural and tensile properties as compared to the neat HDPE. Use of ethylene–glycidyl methacrylate copolymers (E-GMA) in the composites gave the highest tensile modulus, while ethylene, butyl acrylate and maleic anhydride terpolymer (E-BA-MA) led to the highest tensile strength and elongation. The maleic anhydride grafted polyethylene (MAPE) was the most efficient among three coupling agents in improving impact strength. With the addition of 5 wt% E-GMA, E-BA-MA and MAPE, the HDPE/PA6 composites exhibited an improvement of 87, 116, and 387 %, respectively, compared to the uncoupled controls. The PA6 microfibers exhibited a regular orientation along the stretching direction in the presence of 2.5 wt% coupling agents; increasing the loading level of coupling agents caused a reduction in the diameter of PA6 microfibers. FT-IR analyses showed the reactions between PA6 and the coupling agents used.

Comparative genomics reveals candidate carotenoid pathway regulators of ripening watermelon fruit

BackgroundMany fruits, including watermelon, are proficient in carotenoid accumulation during ripening. While most genes encoding steps in the carotenoid biosynthetic pathway have been cloned, few transcriptional regulators of these genes have been defined to date. Here we describe the identification of a set of putative carotenoid-related transcription factors resulting from fresh watermelon carotenoid and transcriptome analysis during fruit development and ripening. Our goal is to both clarify the expression profiles of carotenoid pathway genes and to identify candidate regulators and molecular targets for crop improvement.ResultsTotal carotenoids progressively increased during fruit ripening up to ~55 μg g-1 fw in red-ripe fruits. Trans-lycopene was the carotenoid that contributed most to this increase. Many of the genes related to carotenoid metabolism displayed changing expression levels during fruit ripening generating a metabolic flux toward carotenoid synthesis. Constitutive low expression of lycopene cyclase genes resulted in lycopene accumulation. RNA-seq expression profiling of watermelon fruit development yielded a set of transcription factors whose expression was correlated with ripening and carotenoid accumulation. Nineteen putative transcription factor genes from watermelon and homologous to tomato carotenoid-associated genes were identified. Among these, six were differentially expressed in the flesh of both species during fruit development and ripening.ConclusionsTaken together the data suggest that, while the regulation of a common set of metabolic genes likely influences carotenoid synthesis and accumulation in watermelon and tomato fruits during development and ripening, specific and limiting regulators may differ between climacteric and non-climacteric fruits, possibly related to their differential susceptibility to and use of ethylene during ripening.