Levels Of Ethylene Production Research Articles

An assay for assessing 1-aminocyclopropane-1-carboxylate malonyl (MACC) transferase (AMT) activity and its regulation by ethylene.

N-malonyl 1-aminocyclopropane-1-carboxylic acid (MACC) is a major conjugate of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and may therefore play an important role in regulating ethylene production, as well as ethylene-independent ACC signalling. While the enzyme responsible for this derivatization, ACC malonyltransferase (AMT), has been studied in the past, its identity remains unknown. Methods to assay AMT activity are not well established, and no standardized assay has been described. We optimized an AMT activity assay and investigated the biological implications of AMT. This assay can be divided into three parts: total protein extraction, in vitro AMT activity assay, and MACC detection. For these three parts, different parameters were optimized and combined into an integrated and robust protocol. We used gas chromatography for the indirect detection of MACC, which was compared to a direct LC-MS approach, indicating that the GC-based method is a good alternative readily available to most labs studying ethylene. Next, we used this in vitro AMT activity assay to study the biological function of MACC formation. We observed an ontogenetic, tissue-specific and an ethylene-mediated feedback effect on AMT activity in tomato and Arabidopsis. The feedback of ethylene on AMT activity seems to be important to regulate ethylene production levels. The optimized and robust AMT activity assay presented here will enable other plant researchers to investigate the biochemistry of the ethylene biosynthesis pathway through ACC conjugation into MACC. Our AMT activity method was deployed both in tomato and Arabidopsis, and revealed that AMT activity is tightly controlled by ethylene itself in a tissue-specific way.

Localization of Genetic Factors that Determine the Economically-Useful Traits of the PEAR (<i>Pyrus</i>) and Methods of Marker-Assisted Selection

DNA markers are an alternative method for accelerated identification of interested genes and loci at the early stages of ontogenesis, and, consequently, DNA markers are able to intensify the breeding process. This article represents overview of research on the localization of economically useful traits in the pear genome and the development and use of marker-assisted selection (MAS) techniques. At the moment, several traits have been localized in the pear genome, i.e.: resistance to scab European (V. pirina Aderh) and Asian (V. nashicola), black spot (Alternaria alternata (Fr.) Keissler), brown spot (Stemphylium vesicarium), fire blight (Erwinia amylovora), pear psylla (Cacopsylla pyri), pear sawfly (Caliroa cerasi), pear blister mite (Eriophyes pyri), self-incompatibility, dwarf trait. Major genes and loci of quantitative traits (QTLs) of fruits characteristics have also been identified, namely: skin color and rustiness of the fruit, size and weight of the fruit, taste, level of ethylene production, harvest time etc. It should be noted that currently Russian research is limited to the validation and use of MAS methods developed abroad. According to the experience of Japanese scientists, the use of MAS for several key traits has made it possible to triple the efficiency of the breeding process. Despite the currently limited list of MBC methods for pears, the high speed of genomic technologies development promises rapid development of new MAS methods in the future. In combination with new breeding technologies (New Breeding Techniques) based on accelerated flowering, the use of MAS for pears is a promising direction of breeding.

Effect of temperature, 1-methylcyclopropene, and modified atmosphere packaging on the post-harvest behavior of lulo (Solanum quitoense Lam)

Lulo (Solanum quitoense Lam) is a tropical fruit with high market potential but short shelf life. In this work, the effect of temperature, the application of 1-methylcyclopropene (1-MCP), and the use of modified atmosphere packaging (MAP) were evaluated on the preservation of fresh lulo fruits. Three independent experiments were made sequentially: in the first one, an adequate refrigeration temperature was established (between 5 and 18 °C), then in the second experiment, a suitable dose and application time of 1-MCP (0.35–1.0 μL L−1 and 10–15 min) were found and finally, the combined effect of refrigeration, 1-MCP, and MAP were determined in the last experiment. In the experiments with 1-MCP and MAP, some fruits were stored at refrigeration (5 °C) and then at room temperature (23 °C) while others were kept at room temperature the whole test. Different properties such as respiration, ethylene production, color index, and gas level were evaluated in the samples to determine post-harvest changes. Given the fruit behavior during cold storage, 5 °C proved to be more favorable for preservation. Likewise, samples treated with 0.70 μL L−1 1-MCP + 15 min immersion showed lower CO2 and ethylene production throughout cold storage and shelf time compared with other 1-MCP treatments. For the tests with MAP, the combined treatment with 1-MCP and at 5 °C resulted in a lower respiratory rate, ethylene production, and physicochemical changes during the evaluation (24 days of cold storage + 16 days of shelf time). The results obtained can contribute to increasing the possibilities of lulo commercialization and marketing.

The effect of cold stress on ethylene biosynthesis and sensitivity in cut lily ‘Marlon’

Fresh cut lily flowers often have a long postharvest life and produce undetectable levels of ethylene. This changes after cold storage, when lilies produce a higher amount of ethylene with a very early leaf and then flower senescence. Such changes to postharvest physiology are likely ethylene-dependant, either due to a higher level of ethylene production or a change in ethylene sensitivity as a result of alteration in the expression of genes involved in the biosynthesis, perception and signalling of ethylene. Therefore, we investigated the transcriptional regulation of ethylene biosynthesis, perception, and signalling pathways in response to cold storage in the cut lily cultivar ‘Marlon’. Cut lily stems were treated as follows: 1) control (no treatments), 2) 1-Methylcyclopropene (1-MCP; an ethylene action inhibitor) (10 nL L−1), 3) ethylene (10 μL L−1), and 4) 1-MCP (10 nL L−1) + ethylene (10 μL L−1) for 12 h, thereafter, half of each treated group were cold stored at 5 °C in 12 h light/dark condition for 7 days. We assessed quality characteristics, ethylene production, and the expression of its biosynthesis, perception, and signalling genes. Ethylene and 1-MCP treatments had no effects on non-cold-stored plants. Cold storage led to much earlier leaf yellowing (from 8 to 4 days), and flowers senesced and abscised 3 days earlier. In cold-stored plants, flower senescence and abscission were hastened by ethylene and delayed by 1-MCP. These findings indicate that ethylene does influence flower senescence following cold storage but leaf senescence is under the control of other factors. Our results suggest that treatments that focus on ethylene blockers to prolong postharvest life in lilies will be effective for flowers but not leaves.

Overexpression of Sly-miR167a delayed postharvest chilling injury of tomato fruit under low temperature storage

Chilling injury (CI) of tomato fruit leads to the deterioration of fruit quality, thereby shortening the shelf life of tomato fruit. The present experiment investigates the effect of Sly-miR167a on postharvest cold tolerance of tomato fruit. Results demonstrated that overexpression of Sly-miR167a in tomato fruit effectively reduced electrolyte leakage (EL), hydrogen peroxide (H2O2) content, malondialdehyde (MDA) content and CI index during low temperature storage. Compared with wild-type (WT) and the silencing miR167a by short tandem target mimic (miR167a-STTM) fruit, overexpression of Sly-miR167a (miR167a-OE) fruit accumulated more ascorbic acid (AsA), proline, lycopene, and phenolics, and also maintained higher activities of antioxidant enzymes. At low temperatures, miR167a-OE fruit sustained better quality, and had lower expression levels of ARF6a, higher levels of ethylene production and higher expression levels of CBF1. Overexpression of Sly-miR167a delayed the appearance of CI symptoms, improving the chilling tolerance of postharvest tomato fruit.

MYB30 Regulates Submergence Tolerance by Repressing Ethylene Biosynthesis via ACS7 in Arabidopsis.

Floods impose detrimental effects on natural and agro-ecosystems, leading to a significant loss of worldwide crop production. Global climate change has even worsened this situation. Flooding is a continuous process including two stages of submergence and re-oxygenation, and both are harmful to plant growth and development, resulting in a serious decline in crop yield. Therefore, the understanding of plant flooding tolerance and developing flooding-resistant crops are of great significance. Here, we report that the Arabidopsis thaliana (Arabidopsis) R2R3-MYB transcription factor MYB30 participates in plant submergence response through 1-aminocyclopropane-1-carboxylic acid synthase 7 (ACS7) by repressing ethylene (ET) biosynthesis. The MYB30 loss-of-function mutant exhibits reduced submergence tolerance with a higher level of ET production, whereas the MYB30-overexpressing plant displays enhanced submergence tolerance and repressed ET production. The coding gene of ACS7 might be a direct target of MYB30 during the submergence response. MYB30 binds to the promoter of ACS7 and represses its transcription. The ACS7 loss-of-function mutant with defect in ET biosynthesis displays enhanced submergence tolerance, whereas plants overexpressing ACS7 exhibit a submergence-sensitive phenotype. Genetic analysis shows that ACS7 functions downstream of MYB30 in both ET biosynthesis and submergence response. Taken together, our work revealed a novel transcriptional regulation that modulates submergence response in plants.

Comparative Analysis of Gene Expression between Early Maturation Mutant ‘Beni Shogun’ and ‘Fuji’ Cultivars during Fruit Development and Ripening

We aimed to compare the maturation and ripening characteristics of two apple cultivars, early maturation mutant ‘Beni Shogun’ and ‘Fuji’. The study revealed that both cultivars reached full bloom on the same day, but ‘Beni Shogun’ matured earlier than ‘Fuji’. In addition, differences were observed in fruit size, length, width, sweetness, acidity, and ethylene production levels. The study also examined the expression patterns of genes involved in ethylene biosynthesis and signal transduction, as well as those involved in auxin signal transduction and transcriptional regulation, to investigate the putative molecular mechanism behind the distinct fruit development, maturation, and ripening. The expression of the MdACO1 gene showed a sharp increase after the maturation date, whereas the expression of the MdACO7 gene was higher in the early and middle stages of fruit development. The clustering analysis provided insights into the correlation between the phenotypic traits and expression levels of the key genes. They were categorized into three clusters, and the third cluster consisted of six phenotypes, including fruit size, length, width, sweetness, starch content, and ethylene production, as well as the one gene MdACO1. These findings suggest that ‘Beni Shogun’ and ‘Fuji’ have distinct fruit development and ripening behaviors, with ‘Beni Shogun’ maturing earlier than ‘Fuji’.

Analysis of the Postharvest Storage Characteristics of Two New Pear Cultivars ‘Shannongsu’ and ‘Xincixiang’

‘Shannongsu’ and ‘Xincixiang’ were two new late-ripening pear cultivars with high quality, that were bred by our team. In order to clear the postharvest storage characteristics, mature pears were collected and stored at room temperature. Several fruit characteristics were evaluated over time, such as firmness, ethylene release rate, content of aroma components, softening-related enzyme activity, and gene expression. Both ‘Shannongsu’ and ‘Xincixiang’ were crisp and juicy stored after 60 d at room temperature, which exhibited excellent storage characteristics. The storability may be comprehensive result of low levels of ethylene production, aroma synthesis, softening-related activities, and gene expression. The research cleared the storage characteristics of ‘Shannongsu’ and ‘Xincixiang’ at room temperature for the first time, which will provide scientific theoretical guidance for fruit production and marketing.

Hypersensitive-like response in Brassica plants is specifically induced by molecules from egg-associated secretions of cabbage white butterflies

Plants perceive and respond to herbivore insect eggs. Upon egg deposition on leaves, a strong hypersensitive response (HR)-like cell death can be activated leading to egg desiccation and/or dropping. In Brassica spp., including many crops, the HR-like mechanism against eggs of cabbage white butterflies (Pieris spp.) is poorly understood. Using two Brassica species, the crop B. rapa and its wild relative B. nigra, we studied the cellular and molecular plant response to Pieris brassicae eggs and characterized potential insect egg-associated molecular patterns (EAMPs) inducing HR-like cell death. We found that eggs of P. brassicae induced typical hallmarks of early immune responses, such as callose deposition, production of reactive oxygen species and cell death in B. nigra and B. rapa leaf tissue, also in plants that did not express HR-like cell death. However, elevated levels of ethylene production and upregulation of salicylic acid-responsive genes were only detected in a B. nigra accession expressing HR-like cell death. Eggs and egg wash from P. brassicae contains compounds that induced such responses, but the eggs of the generalist moth Mamestra brassicae did not. Furthermore, wash made from hatched Pieris eggs, egg glue, and accessory reproductive glands (ARG) that produce this glue, induced HR-like cell death, whereas washes from unfertilized eggs dissected from the ovaries or removal of the glue from eggs resulted in no or a reduced response. This suggests that there is one or multiple egg associated molecular pattern (EAMP) located in the egg glue a that teresponse in B. nigra is specific to Pieris species. Lastly, our results indicate that the EAMP is neither lipidic nor proteinaceous. Our study expands the knowledge on the mechanism of Brassica-Pieris-egg interaction and is a step closer toward identification of EAMPs in Pieris egg glue and corresponding receptor(s) in Brassica.

A comparison of physicochemical and ripening characteristics of golden-fleshed ‘Haegeum' and green-fleshed ‘Hayward' kiwifruit during storage at 0 °C and ripening at 25 °C

Postharvest storage plays a key role in determining the marketability of kiwifruits. ‘Haegeum’ (Actinidia chinensis var. chinensis cv. ‘Haegeum’), a golden-fleshed kiwifruit, although gained popularity, knowledge of its postharvest qualities is limited. Here, we performed a comparative analysis of the physicochemical characteristics of golden-fleshed ‘Haegeum’ and green-fleshed ‘Hayward’ (A. chinensis var. deliciosa cv. ‘Hayward’) kiwifruit. The fruit were stored for 1, 2, or 3 months at 0 °C after harvest and subsequently transferred to a room at 25 °C for a week to induce ripening. ‘Haegeum’ had lower firmness (∼9 N lower) than ‘Hayward’ during cold storage, which was reversed during ripening, and both cultivars revealed the same firmness after a week of storage at 25 °C. ‘Haegeum’ had higher (>50 %) ascorbic acid content than ‘Hayward,’ which did not reveal significant change during the experimental period. During ripening, a spontaneous increase in respiration rate and ethylene production was observed. ‘Hayward’ had both earlier initiation and higher levels of ethylene production than ‘Haegeum’ after 2 months of storage at 0 °C followed by a week at 25 °C, which c°uld have increased the polygalacturonase expression leading to a faster softening of the fruit. Principal component analysis and heat-map of volatile compounds (VOCs) revealed distinctive changes in individual VOC profiles in both cultivars, suggesting that the VOCs in kiwifruit vary with cultivars. Based on the changes in the expression of genes related to ripening, we proposed a scheme to delineate the ripening process in kiwifruit. In conclusion, the study revealed that both cultivars have different ripening characteristics and can fetch wider marketability owing to better consumer preference. The findings also provided insights into the underlying mechanism of the ripening process in kiwifruit, which will eventually help understand and manage their postharvest qualities.

Stay-green trait ameliorates combined heat and drought stress in wheat

The present study was carried out during rabi 2017-18 at ICAR-Indian Agricultural Research Institute, New Delhi to investigate the effect of stay-green trait on grain yield in wheat under combined heat and drought stress. Two high stay green (GCP 6 and GCP 33) and two low stay green (GCP 23 and GCP 30) Recombinant Inbred Lines (RILs) of wheat along with their parents (HI1500/DBW43) were grown in field conditions under timely sown with irrigation (control) and without irrigation (drought stress), and late sown with irrigation (heat stress) and without irrigation (combined heat and drought stress). High stay-green RILs showed the reduced levels of abscisic acid and ethylene production during anthesis stage under heat, drought and combined stress conditions as compared to low stay green RILs. Furthermore, there was significantly better yield was observed in high stay-green RILs as compared to low stay-green RILs. Thus our study concludes that stay-green traits improve the yield in wheat under combined heat and drought stress condition by delaying the senescence through reduced levels of abscisic acid and ethylene.

PlZFP mediates the combinatorial interactions of abscisic acid with gibberellin and ethylene during flower senescence in cut herbaceous peony

Short vase life is a main factor that limits herbaceous peony’s economic value. We found that in cut herbaceous peony, flower senescence was regulated by the combinatorial interactions among plant endogenous hormones. However, the molecular mechanisms underlying these interactive effects are not well understood. In this study, we describe the identification of PlZFP, which influences flower senescence in herbaceous peony. PlZFP was upregulated during herbaceous peony flower senescence and its expression level was influenced by abscisic acid (ABA), ethylene and gibberellin (GA). PlZFP-silenced petal discs had longer lives while PlZFP-overexpressing transgenic tobacco had short flower longevity. Silencing PlZFP in petal discs reduced the transcript abundances of the endogenous hormone biosynthesis-related genes PlACO1, PlACO3, PlACS1, PlNCED2, and PlAAO and increased the transcript abundance of PlGA3ox1. Overexpression of PlZFP in tobacco flowers showed the opposite influences on these genes. Furthermore, PlZFP directly bound to the PlNCED2 promoter, and silencing PlNCED2 delayed senescence in discs. Silencing of PlZFP reduced ethylene production and ABA levels while increased GA levels in peony petal discs. Moreover, exogenous ABA, ethephon and paclobutrazol (PAC, a GA inhibitor), accelerate senescence in PlZFP-silenced discs. Taken together, the PlZFP-PlNCED2 regulatory checkpoint may positively affect the production of ABA and mediates the combinatorial interactions of ABA with GA and ethylene during flower senescence in cut herbaceous peony.

Increased ACS Enzyme Dosage Causes Initiation of Climacteric Ethylene Production in Tomato.

Fruits of wild tomato species show different ethylene-dependent ripening characteristics, such as variations in fruit color and whether they exhibit a climacteric or nonclimacteric ripening transition. 1-Aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO) are key enzymes in the ethylene biosynthetic pathway encoded by multigene families. Gene duplication is a primary driver of plant diversification and angiosperm evolution. Here, interspecific variations in the molecular regulation of ethylene biosynthesis and perception during fruit ripening in domesticated and wild tomatoes were investigated. Results showed that the activated ACS genes were increased in number in red-ripe tomato fruits than in green-ripe tomato fruits; therefore, elevated dosage of ACS enzyme promoted ripening ethylene production. Results showed that the expression of three ACS isogenes ACS1A, ACS2, and ACS4, which are involved in autocatalytic ethylene production, was higher in red-ripe tomato fruits than in green-ripe tomato fruits. Elevated ACS enzyme dosage promoted ethylene production, which corresponded to the climacteric response of red-ripe tomato fruits. The data suggest that autoinhibitory ethylene production is common to all tomato species, while autocatalytic ethylene production is specific to red-ripe species. The essential regulators Non-ripening (NOR) and Ripening-Inhibitor (RIN) have experienced gene activation and overlapped with increasing ACS enzyme dosage. These complex levels of transcript regulation link higher ethylene production with spatiotemporal modulation of gene expression in red-ripe tomato species. Taken together, this study shows that bursts in ethylene production that accompany fruit color changes in red-ripe tomatoes are likely to be an evolutionary adaptation for seed dispersal.

A 1-aminocyclopropane-1-carboxylic-acid (ACC) dipeptide elicits ethylene responses through ACC-oxidase mediated substrate promiscuity.

Plants produce the volatile hormone ethylene to regulate many developmental processes and to deal with (a)biotic stressors. In seed plants, ethylene is synthesized from 1-aminocyclopropane-1-carboxylic acid (ACC) by the dedicated enzyme ACC oxidase (ACO). Ethylene biosynthesis is tightly regulated at the level of ACC through ACC synthesis, conjugation and transport. ACC is a non-proteinogenic amino acid, which also has signaling roles independent from ethylene. In this work, we investigated the biological function of an uncharacterized ACC dipeptide. The custom-synthesized di-ACC molecule can be taken up by Arabidopsis in a similar way as ACC, in part via Lysine Histidine Transporters (e.g., LHT1). Using Nano-Particle Assisted Laser Desoprtion/Ionization (Nano-PALDI) mass-spectrometry imaging, we revealed that externally fed di-ACC predominantly localizes to the vasculature tissue, despite it not being detectable in control hypocotyl segments. Once taken up, the ACC dimer can evoke a triple response phenotype in dark-grown seedlings, reminiscent of ethylene responses induced by ACC itself, albeit less efficiently compared to ACC. Di-ACC does not act via ACC-signaling, but operates via the known ethylene signaling pathway. In vitro ACO activity and molecular docking showed that di-ACC can be used as an alternative substrate by ACO to form ethylene. The promiscuous nature of ACO for the ACC dimer also explains the higher ethylene production rates observed in planta, although this reaction occurred less efficiently compared to ACC. Overall, the ACC dipeptide seems to be transported and converted into ethylene in a similar way as ACC, and is able to augment ethylene production levels and induce subsequent ethylene responses in Arabidopsis.

Vapor‐Fed Electrolyzers for Carbon Dioxide Reduction Using Tandem Electrocatalysts: Cuprous Oxide Coupled with Nickel‐Coordinated Nitrogen‐Doped Carbon

AbstractEthylene is particularly attractive due to its major importance as a feedstock for various applications including the polymer industry. As such, catalyst and electrolyzer developments are crucial to achieve industrially relevant ethylene production and efficiency levels. Here, a tandem electrocatalyst composed of copper nanocubes and nickel‐coordinated nitrogen‐doped carbon (NiNC) is presented, which is integrated into gas diffusion electrodes (GDEs) for direct conversion of vapor‐fed CO2 into ethylene. Evaluation of tandem GDEs in the vapor‐fed flow electrolyzer shows significantly increased ethylene selectivity in terms of faradaic efficiency and C2H4/CO ratio compared to a non‐tandem copper GDE. The enhancements are attributed to the increased local CO availability near the copper surface via effective CO2 to CO conversion on neighboring NiNC. The experimental results are validated by 3D resolved continuum simulations, which show increased flux of higher‐order products with the added CO flux from NiNC. The practical viability of Cu/NiNC catalyst is further evaluated in a membrane electrode assembly electrolyzer, achieving 40% FE toward ethylene at 150 mA cm−2 and 3.2 V. These findings highlight the high selectivity and formation rate of ethylene achieved by successful device integration of the Cu/NiNC catalyst, demonstrating the potential for implementation in large‐scale sustainable CO2 electrolyzers.

Ethylene Production Affects Blueberry Fruit Texture and Storability.

Ethylene, produced endogenously by plants and their organs, can induce a wide array of physiological responses even at very low concentrations. Nevertheless, the role of ethylene in regulating blueberry (Vaccinium spp.) ripening and storability is still unclear although an increase in ethylene production has been observed in several studies during blueberry ripening. To overcome this issue, we evaluated the endogenous ethylene production of a Vaccinium germplasm selection at different fruit ripening stages and after cold storage, considering also textural modifications. Ethylene and texture were further assessed also on a bi-parental full-sib population of 124 accessions obtained by the crossing between “Draper” and “Biloxi”, two cultivars characterized by a different chilling requirement and storability performances. Our results were compared with an extensive literature research, carried out to collect all accessible information on published works related to Vaccinium ethylene production and sensitivity. Results of this study illustrate a likely role of ethylene in regulating blueberry shelf life. However, a generalisation valid for all Vaccinium species is not attainable because of the high variability in ethylene production between genotypes, which is strictly genotype-specific. These differences in ethylene production are related with blueberry fruit storage performances based on textural alterations. Specifically, blueberry accessions characterized by the highest ethylene production had a more severe texture decay during storage. Our results support the possibility of tailoring ad hoc preharvest and postharvest strategies to extend blueberry shelf life and quality according with the endogenous ethylene production level of each cultivar.

Exogenous abscisic acid regulates primary metabolism in postharvest cherry tomato fruit during ripening

Primary metabolites play crucial roles during fruit development and ripening. Phytohormone abscisic acid (ABA) has been reported to regulate postharvest tomato fruit ripening. However, knowledge about ABA in regulating primary metabolism in tomato fruit is obscure. In the present research, cherry tomato fruit were infiltrated with 1.0 mM ABA or deionized water under vacuum, and kept in darkness for 15 d. The changes of the relative contents of sugars, organic acids, and amino acids, as well as the expression levels of key genes involved in sugar and organic acid metabolisms, were analyzed. Results showed exogenous ABA accelerated tomato fruit ripening, accompanying with the enhanced changes of fruit color and firmness, the higher levels of respiration rate and ethylene production. Meanwhile, exogenous ABA enhanced the relative levels of some primary metabolites, such as glucose, lyxose and fructose; citric acid, citramalic acid, ascorbic acid and gluconic acid; also serine, pyroglutamic acid, GABA, glutamic acid, aspartic acid, asparagine and glutamine (1.69-3.25 folds). Furthermore, exogenous ABA stimulated the expression levels of most key genes (such as SPSs, SPP2, TIV1, Lins, SUSs, PPCs, MDH and CS) (log2 fold change ranged from 1.06 to 3.64). Results indicate ABA is systematically involved in the regulation of primary metabolism, which may provide valuable information for exploring technical means to improve tomato taste and flavor.

A long noncoding RNA functions in high-light-induced anthocyanin accumulation in apple by activating ethylene synthesis.

Anthocyanin production in apple (Malus domestica) fruit and their consequent coloration can be induced by high-light treatment. The hormone ethylene is also essential for this coloration, but the regulatory relationships that link ethylene and light with anthocyanin-associated coloration are not well defined. In this study, we observed that high-light treatment of apple fruit increased anthocyanin accumulation more than moderate-light treatment did and was the main contributor of induced ethylene production and activation of anthocyanin biosynthesis. A transcriptome study of light-treated apple fruit suggested that a long noncoding RNA (lncRNA), MdLNC610, the corresponding gene of which is physically located downstream from the 1-aminocyclopropane-1-carboxylate oxygenase (ACO) ethylene biosynthesis gene MdACO1, likely affects anthocyanin biosynthesis under high-light treatment. Expression and promoter β-glucuronidase reporter analyses further showed that MdLNC610 upregulates expression of MdACO1 and so likely participates in high-light-induced ethylene biosynthesis. Overexpression of MdACO1 and MdLNC610 in apple fruit and calli indicated that a major increase in MdLNC610 expression activates MdACO1 expression, thereby causing an increase in ethylene production and anthocyanin levels. These results suggest that MdLNC610 participates in the regulation of high-light-induced anthocyanin production by functioning as a positive regulator to promote MdACO1 expression and ethylene biosynthesis. Our study provides insights into the relationship between mRNA and lncRNA networks in the ethylene biosynthetic pathway and anthocyanin accumulation in apple fruit.

UV-C Treatment Maintains the Sensory Quality, Antioxidant Activity and Flavor of Pepino Fruit during Postharvest Storage.

This study examines ultraviolet-C (UV-C) treatment supplementation as a means of inhibiting the senescence of pepino fruit after harvest. Pepino fruits were subjected to 1.5 kJ/m2 UV-C treatments and then packed and stored at 10 °C for 28 d. Results showed that 1.5 kJ/m2 UV-C treatment had the greatest ability to maintain firmness, and reduced the level of respiration and ethylene production. Further analysis indicated that the 1.5 kJ/m2 UV-C treatment maintained the content of total soluble solids (TSS), chlorophyll, vitamin C, flavonoids, and total phenolics. Lower levels of malondialdehyde (MDA) and higher levels of antioxidant enzyme activity were found in UV-C treated fruit during storage. An electronic nose (E-nose) and headspace-gas chromatography-mass spectrometry (HS-GC-MS) was used to determine volatile compounds. Results revealed that the UV-C treatment may promote the synthesis of a large number of alcohols and esters by maintaining the overall level of acids, aldehydes, and esters in fruits. This may contribute to the maintenance of the flavor of harvested fruits. In conclusion, 1.5 kJ/m2 UV-C treatment was demonstrated to be an effective treatment for the maintenance of the sensory, nutritional, and flavor parameters of pepino fruit.

Application of γ-Aminobutyric Acid Treatment Differently Affects Physicochemical Characteristics of Tomato Fruits during Post-harvest Storage

The quality of tomato fruit, from harvest to human consumption, requires a lengthy period for shipping, storing, and marketing. γ-aminobutyric acid (GABA) is a good candidate because it is a natural substance produced by plants to defend themselves against stress conditions. In this study, the effect of post-harvest GABA treatments at 0 (control), 5 mM and, 20 mM on the physical and biochemical properties and the polysaccharide content of tomatoes during 28 days of storage were investigated. Our results indicated that 5 mM of GABA treatment increased firmness and shelf-life by maintaining the integrity of fruits compared to control and 20 mM of GABA treated fruits. The fruits treated with 5 mM of GABA decreased the amount of WSP and the expression of cell wall related genes Pectate lyase (PL) and Polygalacturonase (PG). There was not a clear difference in colour index (CI) values among all treated groups at the end of post-harvest storage. Moreover, the tomato fruits treated with 5 mM GABA also showed somewhat less ethylene production, respiration rate and expression level of two ethylene synthesis genes ACS2 and ACS4 towards the end of storage. These results suggested that treatment with 5 mM GABA could be a beneficial strategy for maintaining the morphological and biochemical quality of tomato under post-harvest storage conditions.