Endogenous Ethylene Production Research Articles

1-Methylcyclopropene treatment followed with ethylene treatment alleviates postharvest chilling injury of ‘Xuxiang’ kiwifruit during low-temperature storage

Kiwifruit, a cold-sensitive fruit, often suffers chilling injury (CI) during low-temperature storage. Ethylene plays an important role in regulating cold tolerance in many types of fruit postharvest. However, the effect of ethylene treatment alone or 1-methylcyclopropene (1-MCP) combined with ethylene treatment on CI in harvested kiwifruit under low temperatures remains unclear. In this study, four treatments (air; 1 μL L−1 ethylene; 0.25 μL L−1 1-MCP; and 0.25 μL L−1 1-MCP combined with 1 μL L−1 ethylene) were applied to ‘Xuxiang’ kiwifruit at 20 °C, which were then stored at 0 °C for up to 100 d. Indicators related to the CI of kiwifruit were then evaluated. The results showed that 1 μL L−1 ethylene treatment accelerated the development of CI, with this treatment resulting in the most serious water-soaked appearance and the highest lignin content in pulp tissue among the four treatments and increasing the endogenous production of ethylene, the relative leakage of electrolytes and malondialdehyde (MDA) content. The combination treatment (0.25 μL L−1 1-MCP + 1 μL L−1 ethylene) alleviated CI of ‘Xuxiang’ kiwifruit during low-temperature storage, enhanced the chilling tolerance of kiwifruit by decreasing electrolyte leakage and MDA content to maintain membrane integrity and increased the activities of catalase (CAT) and ascorbate peroxidase (APX). The results of this study reveal a possible superior storage method for ‘Xuxiang’ kiwifruit that allows longer storage than existing methods while maintaining fruit quality: 0.25 μL L−1 1-MCP treatment followed with 1 μL L−1 ethylene treatment and storage at a low temperature.

Is Endogenous Ethylene Production Associated with Increased Shoot Number in Gentian Cultured In Vitro? Developing a Method for Ethylene Measurement at Nano Level within a Gas-exchangeable In Vitro System

We investigated the possibility of either exogenous ethylene or endogenous ethylene production having an association with the increase in shoot number when nodal explants of Gentiana spp. ‘Little Pinkie’ were cultured in an in vitro medium supplemented with ethephon (10 mg⋅L–1). For the first time within an in vitro system, we report the application of laser ethylene detector technology, and optimization of the methodology to quantify concentrations of ethylene (in the part-per-billion range) released from ethephon decomposition within the atmosphere of gas-exchangeable culture vessels including nodal explants. Compared with continuous (continuous measurements on the same replicate of vessels) and repeated (sampling same replicate of vessels every 48 hours) sampling methodologies, the nonrepeated (sampling fresh replicate of vessels every 48 hours) method of measurement of ethylene concentration was more representative of the actual condition within vessels. Although no prior published data exist showing the positive or negative effect of gaseous ethylene in the headspace of culture vessels on bud outgrowth in gentian, our study shows gaseous ethylene in the headspace of culture vessels was not effective in increasing shoot formation in gentian explants cultured in vitro, whereas ethephon supplementation in agar was effective. Plant material in culture vessels did not have a significant effect on ethylene production regardless of the presence or absence of ethephon. Therefore, although ethephon supplementation in the medium produced gaseous ethylene in the headspace, it was unlikely to cause endogenous ethylene production in explants, but it did trigger shoot formation in ‘Little Pinkie’, perhaps through decomposition to ethylene within the explant tissue, enhancing the internal ethylene level possibly at a locally high concentration.

MaRTH1 suppression of ethylene response during banana fruit ripening and is controlled by MaXB3-MaNAC2 regulatory module

RTE1 (Reversion to Ethylene Sensitivity 1) and its homolog RTH play important role in ethylene response through mediating the receptor signaling output, but their role in climacteric fruit ripening is not clear. In this study, we found two RTE1/RTH genes MaRTH1 and MaRTH2 in banana genome. MaRTH1 expression was inhibited by ethylene and down-regulated during ripening, whereas MaRTH2 expression showed no significant changes during the whole ripening process. Transient over-expression of MaRTH1 in bananas inhibited the effect of exogenous ethylene on endogenous ethylene production, thereby delayed fruit ripening. Using MaRTH1 promoter as a target, we performed yeast one-hybrid screening and isolated the NAC transcription factor MaNAC2, a banana ripening-associated transcriptional repressor degraded by an E3 ligase MaXB3 through ubiquitination. DNA-protein binding assays further confirmed that MaNAC2 repressed the expression of MaRTH1 by directly targeting its promoter. Moreover, the MaNAC2 transcriptional repression to MaRTH1 was inhibited by MaXB3, and this inhibitory action was attenuated by the proteasome inhibitor MG132. Collectively, these findings reveal that MaRTH1, which is modulated by MaXB3-MaNAC2 regulatory module, functions as a negative regulator of ethylene response during banana ripening.

CmMYB113 regulates ethylene-dependent sucrose accumulation in postharvest climacteric melon fruit

Sucrose is mainly accumulated in mature oriental melon fruit, and it is generally regulated by ethylene. However, the molecular mechanism of sucrose accumulation induced by ethylene remains largely unknown. Here, high sucrose melon cultivar ‘HS’ and low sucrose melon cultivar ‘LW’ fruit were treated with ethylene and 1-MCP at ethylene release initial stage (27 d after anthesis, DAA), we found that the exogenous ethylene treatment promoted the sucrose accumulation, and enhanced the activity of sucrose phosphate synthase (SPS), as well as the transcript of CmSPS1 in postharvest climacteric melon fruit ‘HS’. However, both treatments had no effect on sucrose accumulation, SPS activity and its transcription in ‘LW’ fruit. In addition, exogenous ethylene increased endogenous ethylene production in ‘HS’ fruit, and had no effect in ‘LW’ fruit, except 5 d after treatment. Also, a strong positive correlation between ethylene and the CmACO1 expression level were observed in ‘HS’. The expression of transcription factor CmMYB113, screened from yeast one hybrid library, was induced by exogenous ethylene treatment in ‘HS’ rather than ‘LW’. Moreover, the yeast one hybrid and GUS activity assays indicated that CmMYB113 could activate the transcription of CmACO1 and CmSPS1 by binding directly to their promoters, respectively. From the findings, it was revealed that the targeted up-regulation of CmACO1 and CmSPS1 by CmMYB113 could be involved in ethylene-dependent sucrose accumulation, which enhanced flavor quality in climacteric melon fruit.

Expression and Characterization of MdERFs with Roles in Apple Softening

A rapid increase in endogenous ethylene production during ripening is related to fruit softening in the apple (Malus domestica Borkh.) cultivar ‘Taishanzaoxia’. Two genes involved in the ethylene response, MdERF1.1 and MdERF2.1, were isolated and characterized. MdERF1.1 and MdERF2.1 were predicted to encode proteins of 252 and 334 amino acids, respectively. MdERF1.1 and MdERF2.1 were expressed in Escherichia coli, and their molecular weights were determined by SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and western blotting analyses (28 and 37 kD, respectively). Sequence comparisons and phylogenetic and secondary structure indicated that MdERF1.1 and MdERF2.1 are members of the ERF family. Both of them include a typical GCC‑box binding domain consisting of an α-helix and a three-stranded anti-parallel β-sheet. Sequence comparisons showed that MdERF1.1 is highly identity to MdERF1 from ‘Golden Delicious’, but Gly replaces Ala at position 110 in β-strand 2. This amino acid variation may be involved in fruit softening. Similarly, MdERF2.1 is highly identity to MdERF2 from ‘Golden Delicious’ but differs at three amino acids (Ala, Thr and Glu replace Pro, Ala and Asp at positions 97, 139, and 269, respectively). These three amino acid differences in MdERF2.1 might also be related to fruit softening. In ripening fruit, MdERF1.1 transcript levels rapidly increased during fruit softening in ‘Taishanzaoxia’, and this increase was associated with ethylene production. MdERF2.1 was predominantly expressed in softening ‘Taishanzaoxia’ fruit. The results indicate that ethylene signaling and MdERF1.1 and MdERF2.1 are involved in fruit softening in ‘Taishanzaoxia’.

Thinning flat peaches with ethephon and its effect on endogenous ethylene production and fruit quality

Peach orchards are usually hand-thinned at around 40–60 days after bloom, but this practice is labor-intensive and costly. Ethylene plays a key role in peach fruitlet abscission and foliar applications of ethephon have been reported to be effective in some cultivars to induce fruit abscission. However, results are inconsistent and there are no experiences about its application in flat peaches and/or about inducing flowers abscission. Ethephon (from 0 to 300 mg L–1) was applied to ‘Flatbeauti’ peach trees at 30 % and 100 % of full bloom and 30, 40 and 50 DAFB to determine the best time to induce flowers or fruitlet abscission, as well as to investigate its effect on fruit quality parameters and its relationship to the ethylene evolution pattern throughout peach fruit growth. Abscission and ethylene production were related to ethephon concentration. In general, as a mean of three independent experiments, there was an 8–9 % reduction in fruit set, a 3–14 % increase in fruit size, and a 10–16 % reduction in yield, with each incremental increase of 75 mg L–1 ethephon. The late ethephon applications increased ethylene endogenous production up to harvest and this influenced fruit maturity. Finally, our results indicate that ethephon in the range of 150 mg L–1 can be used at 100 % full bloom and at 30–40 DAFB to induce adequate levels of fruit crop load in ‘Flatbeauti’ peaches without other side effects.

Postharvest Properties of Ultra-Late Maturing Peach Cultivars and Their Attributions to Melting Flesh (M) Locus: Re-evaluation of M Locus in Association With Flesh Texture.

The postharvest properties of two ultra-late maturing peach cultivars, “Tobihaku” (TH) and “Daijumitsuto” (DJ), were investigated. Fruit were harvested at commercial maturity and held at 25°C. TH exhibited the characteristics of normal melting flesh (MF) peach, including rapid fruit softening associated with appropriate level of endogenous ethylene production In contrast, DJ did not soften at all during 3 weeks experimental period even though considerable ethylene production was observed. Fruit of TH and DJ were treated with 5,000 ppm of propylene, an ethylene analog, continuously for 7 days. TH softened rapidly whereas DJ maintained high flesh firmness in spite of an increase in endogenous ethylene production, suggesting that DJ but not TH lacked the ability to be softened in response to endogenous and exogenous ethylene/propylene. DNA-seq analysis showed that tandem endo-polygalacturonase (endoPG) genes located at melting flesh (M) locus, Pp-endoPGM (PGM), and Pp-endoPGF (PGF), were deleted in DJ. The endoPG genes at M locus are known to control flesh texture of peach fruit, and it was suggested that the non-softening property of DJ is due to the lack of endoPG genes. On the other hand, TH possessed an unidentified M haplotype that is involved in determination of MF phenotype. Structural identification of the unknown M haplotype, designated as M0, through comparison with previously reported M haplotypes revealed distinct differences between PGM on M0 haplotype (PGM-M0) and PGM on other haplotypes (PGM-M1). Peach M haplotypes were classified into four main haplotypes: M0 with PGM-M0; M1 with both PGM-M1 and PGF; M2 with PGM-M1; and M3 lacking both PGM and PGF. Re-evaluation of M locus in association with MF/non-melting flesh (NMF) phenotypes in more than 400 accessions by using whole genome shotgun sequencing data on database and/or by PCR genotyping demonstrated that M0 haplotype was the common haplotype in MF accessions, and M0 and M1 haplotypes were dominant over M2 and M3 haplotypes and co-dominantly determined the MF trait. It was also assumed on the basis of structural comparison of M haplotypes among Prunus species that the ancestral haplotype of M0 diverged from those of the other haplotypes before the speciation of Prunus persica.

Identification of ACC synthetase genes in Volvariella volvacea and analysis of their response to ethephon and 1-methylcyclopropene treatments

Straw mushroom (Volvariella volvacea) is economically important in China, but after harvest, it can be stored for only 1–2 d, because it rapidly deteriorates. The role of the ethylene signal transduction pathway in the regulation of these processes in higher fungi is unclear. In this study, we aimed to identify and analyze the acs genes in the genome of V. volvacea. Bioinformatic analyses were performed to identify differences between the acs sequences of V. volvacea and homolog gene sequences of plants. Furthermore, ethylene production and acs expression in V. volvacea during storage were measured before and after ethephon and 1-methylcyclopropene (1-MCP) treatments. The results showed that there are four acs genes in the genome of V. volvacea, and the phylogenetic tree revealed that the proteins encoded by these genes had high homology to the ACS proteins in plants, with some differences. A conserved motif was found in these ACS proteins. Ethephon accelerated endogenous ethylene production and upregulated acs expression in V. volvacea, whereas 1-MCP inhibited endogenous ethylene production and downregulated acs expression in V. volvacea. Our study provides valuable data to further investigate the roles of acs in the mechanisms of senescence of V. volvacea. Further, acs could be used to develop molecular markers enabling screening and selective breeding of V. volvacea strains with slowed senescence, prolonging the shelf life of the product.

Effect of 1-MCP and ethylene absorbent on the development of lenticel disorder of 'Xinli No.7' pear and possible mechanisms.

A common lenticel disorder which occurs in the peel of 'Xinli No. 7' pears (Pyrus bretschneideri Rehd.) had not previously been described. Symptoms of this lenticel disorder include enlarging and bulging of the lenticels which results in significant commercial losses. Understanding the physiological basis of lenticel disorder and developing practical methods to control it is crucial for the successful marketing of this pear. The development of this lenticel disorder was found to be closely related to the endogenous ethylene production during storage. 1-Methylcyclopropene (1-MCP) combined with an ethylene absorbent (EA) treatment was found to significantly reduce the development of the disorder by inhibiting the expression of ethylene related genes, PbACS1, PbACS2 and PbACO. It is proposed that the enlarged lenticels may result from increased lignin accumulation in the peel cells, which is inhibited by this combined postharvest treatment. It was shown that the expression of six lignin related genes decreased following the treatment. The results suggest that PbPAL, Pb4CL and PbCAD could be critical in regulating the development of this lenticel disorder. Endogenous ethylene plays a key role in the development of this lenticel disorder in 'Xinli No. 7' pear. The enlarged lenticels which is characteristic of this disorder maybe related to increased lignin accumulation in the peel cells, which were inhibited with 1-MCP combined with an EA treatment. These results provide a practical method for managing the development of lenticel disorder in 'Xinli No. 7' pear and helps clarify the developmental mechanisms of this disorder. © 2020 Society of Chemical Industry.

Ethylene-mediated apoplastic barriers development involved in cadmium accumulation in root of hyperaccumulator Sedum alfredii

Ethylene is an important phytohormone for plant adaptation to heavy metal stress. However, the effects of ethylene on radial apoplastic transport of Cd remain elusive. This study investigated the role of ethylene on apoplastic barriers development and consequences for Cd uptake in Sedum alfredii. In response to Cd, endogenous ethylene production in hyperaccumulating ecotype (HE) roots was decreased due to the down-regulated expressions of ethylene biosynthesis genes, while the opposite result was observed in non-hyperaccumulating ecotype (NHE). Interestingly, the ethylene emission in HE was always higher than that in NHE, regardless of Cd concentrations. Results of exogenous application of ethylene biosynthesis precursor/inhibitor indicate that ethylene with high level would delay the formation of apoplastic barriers in HE through restraining phenylalanine ammonia lyase activity and gene expressions related to lignin/suberin biosynthesis. Simultaneously, correlation analyses suggest that Cd-induced apoplastic barriers formation may be also regulated by ethylene signaling. By using an apoplastic bypass tracer and scanning ion-selected electrode, we observed that the delayed deposition of apoplastic barriers significantly promoted Cd influx in roots. Taken together, high endogenous ethylene in HE postponed the formation of apoplastic barriers and thus promoted the Cd accumulation in the apoplast of roots.

Transcriptome and phytohormone changes associated with ethylene-induced onion bulb dormancy.

Control of dormancy and sprouting in onion bulbs is commercially important for postharvest management. Although ethylene application is sometimes used to extend dormancy, the underlying mechanisms regulating dormancy transition remain unclear. Since the sprout leaves emerge from the bulb baseplate, we used this tissue to assess the impact of ethylene treatment and storage time on the hormone profile and the transcriptome. Reads from 30 libraries were assembled and annotated, with 94,840 unigenes retained after filtering. The de novo transcriptome assembly was of high quality and continuity (N50: 1809 bp, GC content: 36.21 %), and was used to analyse differential expression and Gene Onotologies. Across two years, applied ethylene resulted in delayed dormancy break and reduced post-dormancy sprout vigour. Ethylene supplementation enhanced endogenous ethylene production and caused a transient climacteric-like increase in respiration. Significant changes in hormone and associated transcript profiles occurred through storage and in response to ethylene. In particular, abscisic acid (ABA) and its metabolite phaseic acid (PA) increased under ethylene during the longer dormancy period; however, cytokinin increases observed during storage appeared largely independent of ethylene treatment. Several hormone-related transcripts showed differential expression over time and/or in response to ethylene. Expression of ethylene biosynthesis (ACO), receptor (EIN4) and transcription factor (EIL3) genes were modified by ethylene, as were ABA biosynthesis genes such NCED, and cytokinin biosynthesis genes such as LOG and CKX. We conclude that ethylene substantially modifies expression of genes in several phytohormone pathways, and some of these changes may underlie the dormancy-extending effects of exogenous ethylene.

Hydrogen gas alleviates postharvest senescence of cut rose 'Movie star' by antagonizing ethylene.

H2 prolonged the vase life and improved the vase quality of cut roses through repressing endogenous ethylene production and alleviating ethylene signal transduction during the entire senescing period. Recently, the application of hydrogen gas (H2) was shown to improve postharvest quality and longevity in perishable horticultural products, but the specific regulation mechanism remains obscure. Here, endogenous ethylene production and the expression of genes in ethylene biosynthesis and signalling pathway were investigated to explore the crosstalk between H2 and ethylene during the senescence of cut roses. Our results revealed that addition of exogenous ethylene by ethephon accelerated the senescence of cut roses, in which 100mg L-1 ethephon displayed the most obvious senescent phenotype. While the applied different concentrations (1%, 10%, 50% and 100%) of hydrogen-rich water (HRW) conducted different affects in alleviating the senescence of cut roses, and 1% HRW displayed the best ornamental quality and the longest vase life by reducing ethylene production, supported by the decrease of 1-aminocyclopropene-1-carboxylate (ACC) accumulation, ACC synthase (ACS) and ACC oxidase (ACO) activities, and Rh-ACS3 and Rh-ACO1 expressions in ethylene biosynthesis. In addition, HRW increased the transcripts of ethylene receptor genes Rh-ETR1 at blooming period from day 4 to day 6 and suppressed Rh-ETR3 at senescence phase at day 8 after harvest. Furthermore, the relevant affection of HRW on Rh-ETR1 and Rh-ETR3 expressions still existed when the ethylene production was compromised by adequate addition of exogenous ethylene in HRW-treated cut rose petals, and HRW directly repressed the protein level of Rh-ETR3 in a transient expression assay. Overall, the results suggested that H2 is involved in neutralizing ethylene-mediated postharvest in cut flowers.

Effect of Ethylene on Cell Wall and Lipid Metabolism during Alleviation of Postharvest Chilling Injury in Peach.

Peach is prone to postharvest chilling injury (CI). Here it was found that exogenous ethylene alleviated CI, accompanied by an increased endogenous ethylene production. Ethylene treatment resulted in a moderately more rapid flesh softening as a result of stronger expression of genes encoding expansin and cell wall hydrolases, especially xylosidase and galactosidase. Ethylene treatment alleviated internal browning, accompanied by changes in expression of polyphenol oxidase, peroxidase and lipoxygenases. An enhanced content of phospholipids and glycerolipids and a reduced content of ceramide were observed in ethylene-treated fruit, and these were associated with up-regulation of lipid phosphate phosphatase, fatty acid alpha-hydroxylase, and golgi-localized nucleotide sugar transporter, as well as down-regulation of aminoalcohol phosphotransferases. Expression of two ethylene response factors (ERFs), ESE3 and ABR1, was highly correlated with that of genes involved in cell wall metabolism and lipid metabolism, respectively. Furthermore, the expression of these two ERFs was strongly regulated by ethylene treatment and the temperature changes during transfer of fruit into or out of cold storage. It is proposed that ERFs fulfill roles as crucial integrators between cell wall modifications and lipid metabolism involved in CI processes ameliorated by exogenous ethylene.

‘Passe Crassane’ pear fruit (Pyrus communis L.) ripening: Revisiting the role of low temperature via integrated physiological and transcriptome analysis

European pear fruit (Pyrus communis L.) respond to low temperature (LT) treatments by inducing ethylene production and fruit ripening. However, it is unclear to what extent this response is the result of LT alone or LT-induced ethylene production. In this study, we followed the physiological and molecular responses of ‘Passe Crassane’ pears to LT and the ethylene analogue, propylene, at various storage temperatures. Fruit at 20 °C treated with propylene softened to eating firmness (13–21 N) within 9–10 d, with little changes in endogenous ethylene production (< 0.03 μg kg−1 s−1). By contrast, LT-treated fruit (0 °C and 5 °C for 42 d) produced large amounts of ethylene (1–2 μg kg−1 s−1), and rapidly softened to < 5 N after being transferred to 20 °C. From transcriptomic analyses, we identified 437 differentially expressed genes (DEGs) between propylene-treated and control fruit, which were further augmented by LT treatment. On the other hand, the expression patterns of 763 DEGs between 5 °C vs. 20 °C was not significantly affected by propylene treatment in non-chilled fruit. To examine LT-induced and ethylene-induced pathways separately during chilling, the responses of LT-induced DEGs to 1-methylcyclopropene (1-MCP), an ethylene action inhibitor, were assessed. Among the 763 LT-induced DEGs, 1-MCP treatment disrupted the expression of 390 DEGs, indicating that they were regulated by LT-induced ethylene. Intriguingly, 373 DEGs including transcription factor-related genes such as PcERF98-like, PcATL65, PcMYB6-like, PcGRP2-like, PcTCP7 and PcMBF1c were unaffected by 1-MCP treatment, and thus, likely to be influenced by LT alone. Based on these results, the potential role of these LT-specific genes/pathways as a key factor modulating changes in ethylene production and responsiveness leading to fruit ripening in European pears is discussed.

Modulatory effects of Saussurea lappa root aqueous extract against ethephon-induced kidney toxicity in male rats.

Ethephon (2-chloroethyl phosphonic acid) is a plant growth promoter used to control the plant growth process by liberating ethylene and stimulating the production of endogenous ethylene. Medicinal plants are sources of novel drug discovery targets. Costus (Saussurea lappa) has been used as traditional Chinese medicine. The current study was conducted to examine the possible modifying effects of costus (S. lappa) root aqueous extract against kidney toxicity induced by ethephon in male rats. A total of 50 adult male rats were divided into five groups (first, control; second, costus; third, ethephon; fourth, posttreated ethephon with costus; fifth, ethephon self-healing). There is a significant increase in the serum levels of urea, creatinine, potassium ions, chloride ions, kidney injury, DNA damage, and proliferating cell nuclear antigen expressions in treated rats with ethephon when compared to the control group. In contrast, the treated rats with ethephon revealed a significant decrease in the levels of sodium ions and an insignificant decrease in the calcium ions. Saussurea lappa extract modified these alterations when compared to the control group. As a result, costus root extract significantly reduced rat kidney toxicity after ethephon administration. We recommend costus to be included in diet for its valuable effects, and also producers and consumers should become more aware about the toxic effects of ethephon.

24-Epibrassinolide treatment regulates broccoli yellowing during shelf life

To explore the effect of 24-epibrassinolide (EBR) on the postharvest yellowing of broccoli (Brassica oleracea var. italica) florets, these were treated with 0–20 μM EBR and kept at 4 °C for 24 days (shelf life). Changes in color, chlorophyll fluorescence, chloroplast ultrastructure, and in the activities of enzymes and expression of genes related to ethylene synthesis and chlorophyll degradation were determined. Low EBR concentrations (2–5 μM) effectively inhibited the yellowing of broccoli, while high EBR concentrations (15–20 μM) accelerated it. On the 24th day, the grana thylakoids of the chloroplasts of 2 μM EBR-treated florets were neatly arranged and clearly visible, while the chloroplast membrane and grana thylakoids of the chloroplast of 20 μM EBR-treated florets were dissolved. Chlorophyll fluorescence was significantly higher in broccoli florets treated with low EBR concentrations than in control broccoli; the opposite was found for broccoli treated with high EBR concentrations. In 20 μM EBR- treated broccoli, the expressions of the genes coding for 1-aminocyclopropane-1-carboxylic acid (ACC) synthase 4 (BoACS4), ACC oxidase 3 (BoACO3), pheophytinase (PPH), and polyamine oxidase (PaO) were increased, accelerating the degradation of chlorophyll, while in 2 μM EBR-treated broccoli the expressions of BoACS4 and BoACO3 were lower than in control broccoli, thereby reducing the production of endogenous ethylene and delaying yellowing. Thus, treatment with 2 μM EBR extends the shelf life of broccoli.

Improving the storage quality of Tahitian limes (Citrus latifolia) by pre-storage UV-C irradiation.

UV-C (180-280nm) has been shown to extend the postharvest shelf-life of many horticulture crops. In this study, Tahitian limes (Citrus latifolia) were exposed to 0, 3.4, 7.2 and 10.5kJm-2UV-C then stored for 28days in air at 10°C and 80% RH. Weight loss, peel colour, calyx abscission, ethylene production, respiration rate, total soluble solids (TSS), titratable acidity (TA) and acceptability index were assessed. The results showed that UV-C treatment maintained lime peel green colour and retained calyx attachment after 28days storage. UV-C treatment also affected endogenous ethylene production and respiration rate, where the highest UV-C treatment (10.5kJm-2) maintained low ethylene production and low respiration rates after 28days storage with no differences between the different UV-C intensities. In terms of fruit acceptability, limes were exposed to 10.5kJm-2UV-C had a 60% acceptability index after 28days storage, while untreated control fruit retained acceptability of 39%. In general, the pre-storage UV-C treatments did not affect fruit weight loss, TSS or TA contents during storage.

Postharvest UV-C Treatment, Followed by Storage in a Continuous Low-Level Ethylene Atmosphere, Maintains the Quality of ‘Kensington Pride’ Mango Fruit Stored at 20 °C

Mature green ‘Kensington Pride’ mangoes (Mangifera indica L.) were treated with a short-term UV-C light at four different intensities (0, 4.0, 8.3 and 11.7 kJ m−2). After treatment, mangoes were stored for 12 d in air (&lt;0.005 μL L−1 ethylene) or 0.1 μL L−1 ethylene at 20 °C and 100% relative humidity (RH). Weight loss, peel colour, firmness, ethylene production, respiration rate, total soluble solids (TSS), titratable acidity (TA), total chlorophyll content, total phenolic content (TPC) and total antioxidant activity were assessed at 3-d intervals. The results showed that UV-C treatment delayed skin degreening, reduced endogenous ethylene production, suppressed respiration rate and lowered chlorophyll content compared to untreated control fruit. Fruit treated with UV-C had significantly higher TPC and total antioxidant activity at the end of the storage period than untreated fruits for both storage atmospheres. In addition, UV-C treated fruits remained significantly firmer than untreated fruits. UV-C treatment significantly affected TSS and TA levels in different ways. Storage of fruits in 0.1 μL L−1 ethylene significantly affected fruit firmness, respiration rate and ethylene production, while other fruit quality parameters were similar to fruit stored in air. These results indicated that UV-C irradiation could be used as an effective and rapid method to extend the postharvest life of mature green mangoes without adversely affecting certain quality attributes in the presence of low-level ethylene during storage.

Ethylene biosynthesis is involved in regulating chilling tolerance and SlCBF1 gene expression in tomato fruit

Ethylene plays positive role in cold response of tomato fruit. CBFs (C-repeat/dehydration-responsive element binding factors) have been proved important in regulating plant chilling tolerance. Till now, the role that ethylene biosynthesis played in chilling response of tomato fruit is still unclear. In this study, we used antisense SlACS2 and wild-type Lichun tomato fruit as inhibited- and normal- ethylene biosynthesis models, in order to investigate whether inhibiting ethylene biosynthesis could affect chilling tolerance and SlCBF1 relative expression in tomato fruit. Results showed that antisense SlACS2 tomato fruit suffered more chilling injury, accompanied by higher malondialdehyde content and ion leakage, less proline and soluble protein content, as well as lower antioxidant enzymes activities, suggesting that inhibiting ethylene biosynthesis reduced tomato fruit chilling tolerance. Furthermore, SlCBF1 expression in transgenic fruit was lower than in WT, the second peak of SlCBF1 expression was coincidence with the peaks of both endogenous ethylene production and ACS activity, and there was significant correlation between ACC content and SlCBF1 relative expression, which implied that endogenous ethylene biosynthesis could contribute to upregulate SlCBF1 expression under cold stress. These results revealed that ethylene biosynthesis played important roles in regulating tomato fruit chilling tolerance and SlCBF1 relative expression in tomato fruit.

Measuring ethylene in postharvest biology research using the laser-based ETD-300 ethylene detector

BackgroundAbility to measure ethylene is an important aspect of postharvest management, as knowledge of endogenous ethylene production is used in assessing physiological status, while response of crops to exogenous ethylene informs efforts needed to control unwanted ripening. An ethylene monitoring device with a laser-based photoacoustic detector, ETD-300, was recently developed by Sensor Sense B.V., Nijmegen, The Netherlands. In terms of performance, the ETD-300 is superior to all other current ethylene measurement devices, with a sensitivity of 0.3 nL L−1, a response time of 5 s, and an ability to monitor ethylene in real time. Although the ETD-300 is relatively easy to operate, the performance and correctness of the data obtained depends on the choice of settings, which depends on the application.ResultsThis article provides a description of different ways in which the ETD-300 can be used in postharvest research for monitoring ethylene production and ethylene presence in an environment. We provided guidelines on selecting the appropriate method (Continuous Flow, Stop and Flow, and Sample methods), and operational curves for deciding on suitable combination of free volume, flow rates, and period for the different measurement methods.ConclusionsUsing these guidelines and operational curves, ETD-300 users can considerably reduce the measurement effort by limiting trial and error in establishing appropriate methodologies for their application. The guidelines also comment on accurate use of the ETD-300, as using the inappropriate settings could lead to erroneous measurements. Although these methodologies were developed primarily for postharvest application, they can be applied in other plant science research.