Higher Ethylene Production Research Articles

Ethylene production by Alternaria alternata and its association with virulence on inoculated grape berries

Ethylene has been shown to promote spore germination and hyphal growth in the phytopathogenic fungus Alternaria alternata. However, little is known about the ethylene biosynthetic pathway in this fungus. In the present study, the ethylene biosynthetic pathway in A. alternata was investigated to explore ethylene-associated virulence of this fungus. The strain A0 of A. alternata did not produce ethylene on basal medium with different possible precursors or intermediates for ethylene biosynthesis (glutamate, aspartate, 2-oxoglutarate and 1-aminocyclopropano −1-carboxylic acid). However, ethylene production was observed when methionine was added as a precursor to the medium and was further promoted by continuous light illumination. Furthermore, addition of 2-keto-4-methylthiobutyric acid (KMBA) promoted ethylene production in the absence of methionine, indicating that the KMBA pathway was mainly responsible for ethylene biosynthesis in this fungus. The strain A0 was inoculated into grape berries to examine the effect of ethylene production on its virulence (as assessed by lesion formation at the inoculation site). The results indicated that higher ethylene production caused larger lesion formation. Similar results were also obtained when isolates of A. alternata, obtained from infected grapes, were inoculated. Thus, the present study thus demonstrated that A. alternata produces ethylene via the KMBA pathway and utilizes it for enhanced virulence expression during infection.

Changes in quality of fresh-cut wax-apple (Syzygium samarangense) as affected by storage period and cut sizes

Wax apple (Syzygium samarangense) is a tropical fruit with attractive appearance and thirst-relieving properties, offering a unique apple-like crispness, watery-sweet, low-acid taste and the aroma of roses. Compared to whole fruit, fresh-cut fruits are more perishable due to high respiration, ethylene production, and membrane degradation, thus reducing fruit usage. This paper reports the effect of storage period and cut sizes on quality of fresh-cut wax apples. Fresh wax apple fruits were prepared according to the treatments: whole, halved (1/2), quartered (1/4), and wedged (1/8) and stored in a domestic refrigerator (4°C), in a clear plastic container (ca. 260-280 g). Results showed that there was a significant interaction between storage period and cut sizes on weight loss. Samples stored as whole lost the least amount of water. Weight loss for all cut sizes were less than 1.6%. The firmness of wax apple on day 9 of storage was significantly lower than their initial firmness. The whole fruit was found to be softer than the freshly cut samples. Total soluble solids content decreased with the time of storage, reduced from 7.6 to 6.2 °Brix as the storage period extended from day 0 to day 9 irrespective of cutting sizes. Titratable acidity increased significantly from day 0 to day 3 of storage for halved, quartered and wedged fruit. The concentration of ascorbic acid decreased significantly throughout the period of storage. Overall, results clearly showed that storage period markedly affected the physico-chemical properties of wax apples regardless of their cut sizes but not to the extent that the quality of fresh-cut wax apple was reduced.

Inhibition of Ethylene Biosynthesis and Perception by 1-Methylcyclopropene and Its Consequences on Chlorophyll Catabolism and Storage Quality of ‘Bosc’ Pears

Bosc is a winter cultivar of european pear (Pyrus communis) that has a relatively short storage life partially due to a high ethylene production rate (EPR) during cold storage. ‘Bosc’ pears were harvested at commercial maturity and treated with gas 1-methylcyclopropene (1-MCP) at 0, 0.15, and 0.3 µL·L−1 and stored at −1.1 °C for 8 months. Results indicated that all 1-MCP treatments inhibited EPR and respiration rate (RR), retarded the degradation of chlorophyll and titratable acidity (TA), and extended storage quality; but inhibited ripening capacity. 1-MCP at 0.15 and 0.3 µL·L−1 had the same efficacy on keeping fruit quality although its higher rate was more efficient on inhibiting EPR and RR. The expression of ethylene synthesis genes (PcACS1, PcACS2, PcACS4, PcACS5, and PcACO1) and receptor genes (PcETR1, PcETR2, and PcERS1) was upregulated in control fruit during storage and they were downregulated significantly by 1-MCP treatments. In contrast, the ethylene receptor genes of PcETR5 and PcCTR1 were downregulated in control fruit during storage and were unaffected by 1-MCP treatments. Although the transcription levels of chlorophyll degradation genes PcPPH, PcNOL, PcSGR, PcRCCR, PcNYC, and PcPAO were all upregulated in control fruit during storage and downregulated by 1-MCP; only PcCHL was downregulated in the control and 1-MCP had no consistent effect on it. The relationship of ethylene biosynthesis/perception with chlorophyll degradation and storage quality in european pears was discussed.

Enhanced production of 3-methylthiopropionic ethyl ester in native Iranian Cucumis melo L. Group dudaim under regulated deficit irrigation

Sulfur esters such as 3-methylthiopropionic ethyl ester (MTPE) significantly influence taste and fragrance of melons. Nutraceutical properties of MTPE have been demonstrated. GC–Mass analysis confirmed MTPE presence in two Cucumis melo L. Group dudaim cultivars of Iran, Birjand and Kerman. Considering potential effect of abiotic stresses on biosynthesis of esters, both cultivars were subjected to regulated deficit irrigation (RDI) at three levels of matric potentials [control (−50kPa), moderate (−65kPa), high (−75kPa)]. MTPE production rose from 1.55 and 2.8μg/kg of fresh pulp under control RDI to 7.65 and 9.1 under moderate and to 19.3 and 27.8μg/kg under high RDI in Birjand and Kerman samples, respectively. MTPE higher production was accompanied by higher ethylene production and increased alcohol dehydrogenase activity. Ten-fold increase in MTPE production was assumingly owing to higher activities of the esterification enzymes which were supported by sulfur substrates coming from the accelerated methionine catabolism.

The Effect of Postharvest UV-C Treatment and Associated with Different Storage Conditions on the Quality of Tahitian Limes (Citrus latifolia)

Tahitian limes (Citrus latifolia) were exposed to 0 and 7.2 kJm-2 UV-C. After treatments, it was stored for 28 days in air at 20°C, 80% RH (control) and in air containing <0.005 or 0.1 μL.L−1 ethylene at 20°C and 100% RH. Weight loss, peel colour, calyx abscission, ethylene production, respiration rate, soluble solids content (SSC), titratable acidity (TA) and acceptability index were assessed. The UV-C light treatment significantly affected the quality of lime during storage. UV-C treatment significantly affected peel degreening at 20°C in all storage conditions, whereas treated limes showed significantly lower in peel degreening than the control. These effects reduced over the storage time, with the exception of fruits stored in <0.005 μL.L-1 ethylene which still produced a significantly higher in Hue value after 21 days storage relative to the control. UV-C treatment affected ethylene production during storage under all storage conditions. This effect also diminished with storage time. UV-C treatment did not affect the respiration rate, SSC or TA for all storage conditions. The UV-C treated limes had higher acceptability index than untreated limes up to 14 days storage at 20°C. Storage conditions significantly affected ethylene production, with limes that stored in air exhibiting higher ethylene production than fruits stored in the <0.005 or 0.1 μL.L-1 ethylene atmosphere. Storage conditions also significantly affected weight loss, with fruits stored in air showing greater weight loss compared to the other storage conditions. The results suggest that a pre-storage UV-C treatment, followed by storage in less than 0.1 μL.L-1 ethylene atmosphere improves the quality of limes postharvest.

Patterns of flesh reddening, translucency, ethylene production and storability of ‘Friar’ plum fruit harvested at three maturity stages as affected by the storage temperature

Flesh reddening and translucency are two predominant physiological disorders of ‘Friar’ plum (Prunus salicina Lindl.) during cold storage. In order to investigate the occurrence of these disorders, the fruit were harvested at early-, mid- and late-maturity stages and stored at 0, 2, 5, 15 or 25°C, 85–95% relative humidity. Three concomitant patterns for flesh reddening, translucency and abnormal softening (melting) of ‘Friar’ plums were evident: rapid increases in these disorders at 5 and 15°C, a delayed/suppressed of these disorders at 0 and 2°C, and normal ripening at 25°C, irrespective of fruit maturity stage. Three similar temperature-mediated patterns of anthocyanin accumulation related to flesh reddening, pectin solubilization related to translucency, and decline in firmness related to abnormal softening were observed. Three patterns of ethylene production were also identified: early and dramatically high ethylene production at 5 and 15°C, suppressed ethylene production at 0 and 2°C, and almost no ethylene production at 25°C. These results suggest that ethylene may be involved in the onset and development of flesh disorders of ‘Friar’ plums during cold storage. Respiration greatly increased, water-soluble pectin content increased early during storage and remained high, and insoluble pectin (i.e., protopectin) decreased, in plums held at 5 and 15°C. Overall, the biochemical and physiological behavior of plums were greatly affected by storage at 5 and 15°C compared with 0, 2 and 25°C, and late-maturity plums were more susceptible to storage disorders.

Editorial: Ethylene's Role in Plant Mineral Nutrition.

Editorial: Ethylene's Role in Plant Mineral Nutrition.

Supraoptimal ethylene acts antagonistically with exogenous gibberellins during Solanum lycopersicum (Solanaceae) hypocotyl growth.

In many plant species, ethylene and gibberellins interact to regulate plant growth and development. In some cases, these hormones can act in a synergistic way whereas in others they can be antagonistic. To date, the control of hypocotyl elongation by ethylene and gibberellins has been poorly explored in tomato. In this paper, we report that, application of exogenous ethylene to tomato seedlings or high endogenous ethylene production, as in the epinastic mutant, strongly prevent the effect of gibberellic acid (GA3) application. Moreover, constitutive activation of gibberellin signal in a DELLA deficient mutant is not able to counteract the inhibitory effect of ethylene on hypocotyl elongation, suggesting that ethylene acts independently from DELLA-mediated gibberellin response. Interestingly, when ethylene perception is blocked, the GA3 promotive effect on hypocotyl length is less effective, indicating that the presence of a basal level of ethylene could synergistically enhance hypocotyl growth. Taken together, these observations may suggest that, in tomato, supraoptimal concentrations of ethylene are able to antagonize gibberellin effect but normal levels seem to promote gibberellin-induced hypocotyl elongation.

1-MCP treatment enhanced expression of genes controlling endosperm cell division and starch biosynthesis for improvement of grain filling in a dense-panicle rice cultivar

High ethylene production in dense-panicle rice cultivars impacts grain filling. 1-MCP (ethylene action inhibitor) treatment increased assimilates partitioning, cell number and size and expression of starch synthesizing enzyme genes of developing caryopses mostly in the basal spikelets of panicle at early post-anthesis stage. The gain in cell number was less compared to the increase of size. High ethylene production in spikelets matched with greater expression of ethylene receptor and signal transducer genes. Genes encoding cell cycle regulators CDK, CYC and CKI expressed poorly on 9 DAA. 1-MCP treatment enhanced their expression; the increase of expression was higher for CDKs and lower for CKIs in basal compared to apical spikelets. Greater expression of CDKB2:1 might have lifted cytokinesis of nascent peripheral cells of endosperm, while promotion of CDKAs, CYCD2:2 and inhibition of CYCB2:2 expression contributed to endoreduplication of central cells increasing cell size and DNA ploidy level. It is concluded that the process of endoreduplication, which begins at mid-grain filling stage, is crucially linked with the final caryopsis size of rice grain. The enhanced endosperm growth brought about by repressed ethylene action during the first few days after anthesis seems to be associated with the overall increased cell cycle activity and sink strength.

Pre and Post-harvest Practices, Processing and Value Addition of Custard Apple

Custard apple is a delicious and commercially important fruit with pleasant flavor, mild aroma, sweet taste, good nutritional and medicinal values. However, the pre-harvest, post-harvest and processing and value addition practices have not been sufficiently developed. The pre-harvest practices like mulching, irrigation nutrition supplement and bio-fertilizers application play an important role on the development and shelf-life of fruits. The fruit has a short self-life due to high respiration and ethylene production. The temperature, type of packaging and chemical application have effect on storage life, however very low temperature storage is not recommended due to chilling injury. The shelf-life of custard apple fruit can be enhanced upto 12 days in modified atmosphere storage at 10 degreesC, whereas pulp can be stored for six months with potassium meta-bisulphite. A number of value added products like ready-to-serve beverages, fermented beverage, ice cream, squash, and toffee can be prepared to exploit the nutritional potential and adding a new flavor/taste in the market. This review attempts to outline some of the important findings on pre-harvest practices, post-harvest, processing value addition and storage of this fruits.

An improved fruit transcriptome and the identification of the candidate genes involved in fruit abscission induced by carbohydrate stress in litchi.

Massive young fruit abscission usually causes low and unstable yield in litchi (Litchi chinensis Sonn.), an important fruit crop cultivated in tropical and subtropical areas. However, the molecular mechanism of fruit drop has not been fully characterized. This study aimed at identification of molecular components involved in fruitlet abscission in litchi, for which reference genome is not available at present. An improved de novo transcriptome assembly was firstly achieved by using an optimized assembly software, Trinity. Using improved transcriptome assembly as reference, digital transcript abundance (DTA) profiling was performed to screen and identify candidate genes involved in fruit abscission induced by girdling plus defoliation (GPD), a treatment significantly decreased the soluble sugar contents causing carbohydrate stress to fruit. Our results showed that the increasing fruit abscission rate after GPD treatment was associated with higher ethylene production and lower glucose levels in fruit. A total of 2,771 differentially expressed genes were identified as GPD-responsive genes, 857 of which were defined by GO and KEGG enrichment analyses as the candidate genes involved in fruit abscission process. These genes were involved in diverse metabolic processes and pathways, including carbohydrate metabolism, plant hormone synthesis, and signaling, transcription factor activity and cell wall modification that were rapidly induced in the early stages (within 2 days after treatment). qRT-PCR was used to explore the expression pattern of 15 selected candidate genes in the abscission zone, pericarp, and seed, which confirmed the accuracy of our DTA data. More detailed information for different functional categories was also analyzed. This study profiled the gene expression related to fruit abscission induced by carbohydrate stress at whole transcriptome level and thus provided a better understanding of the regulatory mechanism of young fruit abscission in litchi.

Effects of 1-methylcyclopropene on function of flag leaf and development of superior and inferior spikelets in rice cultivars differing in panicle types

High ethylene production usually slackens spikelets development in compact panicled rice (Oryza sativa L.) cultivars. 1-Methylcyclopropene (1-MCP) is a potent inhibitor of ethylene action that has been shown to prevent ethylene-induced effects in fruits. However, effects of 1-MCP on spikelets development in rice cultivars differing in panicle types are unclear. This study explored whether 1-MCP is involved in regulating rice flag leaf function, and superior and inferior spikelets development. Four rice cultivars were field grown in 2012 and 2013, including two lax-panicled cultivars, Liangyoupeijiu (LYP9) and Guodao 6 (GD6), and two compact-panicled cultivars, Yongyou 9 (YY9) and Yongyou 12 (YY12). Results showed that 1-MCP played a positive role in regulating photosynthetic rate of rice flag leaf. Application of 1-MCP was more effective on enhancing grain filling rate of LYP9, GD6, and YY9. 1-Aminocyclopropane-1-carboxylic acid synthase (ACS) activity and ethylene production of inferior spikelets were more sensitive to the regulation of 1-MCP comparing to that in superior spikelets. Compared to other cultivars, ACS activity and ethylene production in inferior spikelets of LYP9 with 1-MCP treatment were significantly lower than that in control (CK). Effect of 1-MCP on starch content in superior and inferior spikelets varied with rice cultivars, but application of 1-MCP significantly enhanced starch content of inferior spikelets for LYP9. To compare with CK, application of 1-MCP greatly increased grain yield, spikelet fertility, and harvest index for LYP9, GD6, and YY9, especially for LYP9. Results indicate that 1-MCP favorably regulated flag leaf photosynthesis and inferior spikelets development in rice cultivars used in this trial, and LYP9 showed the best performances after application of 1-MCP.

Spikelet-specific variation in ethylene production and constitutive expression of ethylene receptors and signal transducers during grain filling of compact- and lax-panicle rice (Oryza sativa) cultivars

Grain yields in modern super rice cultivars do not always meet the expectations because many spikelets are located on secondary branches in closely packed homogeneous distribution in these plants, and they do not fill properly. The factors limiting grain filling of such spikelets, especially in the lower panicle branches, are elusive. Two long-duration rice cultivars differing in panicle density, Mahalaxmi (compact) and Upahar (lax), were cultivated in an open field plot. Grain filling, ethylene production and constitutive expression of ethylene receptors and ethylene signal transducers in apical and basal spikelets of the panicle were compared during the early post-anthesis stage, which is the most critical period for grain development. In another experiment, a similar assessment was made for the medium-duration cultivars compact-panicle OR-1918 and lax-panicle Lalat. Grain weight of the apical spikelets was always higher than that of the basal spikelets. This gradient of grain weight was wide in the compact-panicle cultivars and narrow in the lax-panicle cultivars. Compared to apical spikelets, the basal spikelets produced more ethylene at anthesis and retained the capacity for post-anthesis expression of ethylene receptors and ethylene signal transducers longer. High ethylene production enhanced the expression of the RSR1 gene, but reduced expression of the GBSS1 gene. Ethylene inhibited the partitioning of assimilates of developing grains resulting in low starch biosynthesis and high accumulation of soluble carbohydrates. It is concluded that an increase in grain/spikelet density in rice panicles reduces apical dominance to the detriment of grain filling by production of ethylene and/or enhanced perception of the ethylene signal. Ethylene could be a second messenger for apical dominance in grain filling. The manipulation of the ethylene signal would possibly improve rice grain yield.

Aminoethoxyvinylglycine (AVG) ameliorates waterlogging-induced damage in cotton by inhibiting ethylene synthesis and sustaining photosynthetic capacity

In this glasshouse study, we investigated the mechanisms of aminoethoxyvinylglycine (AVG)-induced waterlogging tolerance in cotton. Two cotton cultivars Sicot 71BRF (moderately waterlogging tolerant) and LA 887 (waterlogging sensitive) were grown in a clay-loam soil, and exposed to waterlogging at early squaring stage (53 days after sowing). One day prior to waterlogging, shoots were sprayed with AVG (ReTain®, 830 ppm). Continuous waterlogging for 2 weeks accelerated the shedding of leaves and fruits. As the duration of waterlogging increased, shoot growth rate, biomass accumulation, photosynthesis (P n) and stomatal conductance (g s) were all reduced. Growth of LA 887 was more severely impaired than Sicot 71BRF, with a decline in leaf P n and g s after just 4 h of waterlogging. Waterlogging inhibited allocation of nitrogen (N) to the youngest fully expanded leaves, photosynthesis and biomass accumulation, while it accelerated ethylene production promoting leaf and fruit abscission. AVG blocked ethylene accumulation in leaves and subsequently improved leaf growth, N acquisition and photosynthetic parameters. In addition, AVG enhanced fruit production of both cotton cultivars under waterlogged and non-waterlogged conditions. Higher ethylene production in cotton is linked with fruit abscission, implying that AVG-induced ethylene inhibition could potentially limit yield losses in waterlogged cotton.

THE EFFECT OF PHOTOPERIODISM WITH LED LIGHT ON PRODUCTIVITY OF FEMALE FLOWER IN CUCUMBER (CUCUMIS SATIVUS L.)

Cucumber productivity can be optimize by regulating their photoperiod. Photoperiod will affect the production of female flower, the basis for the production of cucumber fruit. In this research, two cucumber lines (Mercy and KE 27187) was treated with 8, 12, and 16 hours of light by using red light (λred = 630 nm), blue light (λblue = 460 nm), and yellow light (λyellow = 510 nm) LEDs. Treatment from 12 h of light increased sugar accumulation (7482, 69 ppm) but not too different compared to 8 hours and 16 hours treatment. It also produced ethylene 27, 69% (v/v). Meanwhile, 16 hours treatment in KE 27187 line produced highest sugar accumulation (9178, 59 ppm) and ethylene production (21,92% (v/v)). High sugar accumulation and ethylene production could increase the production of female flower. In addition, 16 hours treatment resulted in the highest growth rate (2-4 times higher) and biomass dry weight (2-6 times higher) than other treatments. These results valid for both lines, Mercy and KE 27187. Using this LED Technology, we predicted that Mercy is a short-day plant and KE 27187 is a long-day plant. Article DOI: https://dx.doi.org/10.20319/mijst.2016.s11.2434 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

High oxygen atmospheres can induce russet spotting development in minimally processed iceberg lettuce

High oxygen modified atmospheres have been suggested as an alternative preservation technique to classical low O2 modified atmosphere packaging (MAP) for fresh-cut lettuce. The advantages of high O2 storage would be a strong reduction of browning, avoidance of low O2 levels linked to off-odors, and the inhibition of microbial growth. However, storage under high O2 potentially could increase both production of ethylene and sensitivity to this hormone in lettuce tissue, leading to the development of quality problems linked to ethylene. In this study, different quality parameters (sensory quality, microbiological load, electrolyte leakage, volatile metabolites) were studied on fresh-cut iceberg lettuce stored under different gas conditions at 7°C: (low O2 MAP (3% O2 compensated with N2), atmospheric conditions, high O2 MAP (50 or 90% O2 compensated with N2)). Furthermore, additional experiments using ethylene absorbers were performed in order to assess the link between high O2 storage, ethylene accumulation, and russet spotting. There was no significant difference between storage conditions regarding growth of mesophilic bacteria and yeasts, electrolyte leakage, or ethanol production. On the other hand, high O2 atmospheres reduced browning but promoted russet spotting development compared with low O2 and atmospheric conditions. In further specific experiments the relationship between high O2 storage, ethylene production, and russet spotting in fresh-cut iceberg lettuce were made evident.

Ethylene production in relation to nitrogen metabolism in Saccharomyces cerevisiae.

We have previously shown that ethylene production in Saccharomyces cerevisiae expressing the ethylene-forming enzyme (EFE) from Pseudomonas syringae is strongly influenced by variations in the mode of cultivation as well as the choice of nitrogen source. Here, we have studied the influence of nitrogen metabolism on the production of ethylene further. Using ammonium, glutamate, glutamate/arginine, and arginine as nitrogen sources, it was found that glutamate (with or without arginine) correlates with a high ethylene production, most likely linked to an observed increase in 2-oxoglutarate levels. Arginine as a sole nitrogen source caused a reduced ethylene production. A reduction of arginine levels, accomplished using an arginine auxotrophic ARG4-deletion strain in the presence of limiting amounts of arginine or through CAR1 overexpression, did however not correlate with an increased ethylene production. As expected, arginine was necessary for ethylene production as ethylene production in the ARG4-deletion strain ceased at the time when arginine was depleted. In conclusion, our data suggest that high levels of 2-oxoglutarate and a limited amount of arginine are required for successful ethylene production in yeast.

Ethylene in the Atmosphere of Commercial Potato (Solanum Tuberosum) Storage Bins and Potential Effects on Tuber Respiration Rate and Fried Chip Color

Careful storage management is required to maintain post-harvest potato tuber quality. The plant growth regulator ethylene has well documented effects on potato tuber respiration rate, fried product color, and sprouting, but data on the amount of ethylene present in ventilated potato storages and how ethylene may affect tubers in commercial storage are not available. To address this need, ethylene concentration in ventilated commercial storage bins located in central Wisconsin was quantified using gas chromatography from shortly after bin filling until unloading. Samples of the storage atmosphere were collected approximately every other week from 17, 18 and 14 storage bins in 2010, 2011 and 2012, respectively. Ethylene was present transiently, and only rarely at concentrations greater than 20 nl l−1. In laboratory-scale experiments, chipping potato tubers responded to ethylene at 20 nl l−1 with an increase in tuber respiration rate, but not with an increase in post-fry chip darkening. These data indicate that the impact of atmospheric ethylene on tuber quality and storage management in ventilated potato storages is likely to be small, except near localized regions of high ethylene production.

Desverdecimento e armazenamento refrigerado de tangor ‘Murcott’ em função de concentração e tempo de exposição ao etileno

Degreening treatment has been applied in traditional countries exporters and consumers of fresh citrus to improve rind color of fruit cultivated in regions that no shown low temperature during maturation. In Brazil, this technique is performed empirically, without control of application conditions and fruit shown low extern quality. This study was carried out with the objective to determinate conditions to the technique of postharvest degreening of ‘Murcott’ orange, involving the application of exogenous ethylene. The concentrations 5 and 10 mL L-1 of ethylene was applied inside the chamber for 96 and 120 hours at 25oC and 90% RH. After treatments fruit were stored at 5°C during for 30 days, and after that, plus 3 days at 25ºC. Fruit were evaluated in four periods: after harvest; after degreening treatment, after cold storage and after 3 days at 25°C (simulated marketing). The variable analyzed were: skin color, soluble solids (SS), titratable acidity (TA), ratio (SS/TA), ascorbic acid, percentage of juice, chlorophyll and carotenoids content, chlorophyllase activity, respiratory rate and ethylene production. The treatments did not affect the soluble solids, titratable acidity, ratio, percentage of juice and ascorbic acid content. Fruit treated with ethylene showed increase of color index concomitant by higher chlorophyllase activity and lower chlorophyll content. There were no differences in the carotenoids content in the periods evaluated. Fruit treated with ethylene at both concentrations had higher ethylene production, whereas the dose of 10 mL L-1 favored the incidence of decay. Ethylene 5 mL L-1 for 96 hours is enough to trigger the process of degreening ‘ Murcott’ tangor and can be used to improve skin color of this cultivar.

The addition of rosehip oil improves the beneficial effect of Aloe vera gel on delaying ripening and maintaining postharvest quality of several stonefruit

In this work Aloe vera gel (AV) alone or with the addition of 10 or 2% rosehip oil was used as fruit edible coatings in a wide range of Prunus species and cultivars: peaches (‘Roma’ and ‘B-424-16’ flat type), plums (‘Red Beauty’ and ‘Songria’), nectarine (‘Garofa’) and sweet cherry (‘Brooks’). Following treatments, fruit were stored at 20°C for 6 days and analysed for the effect of treatments on fruit ripening and quality parameters compared with uncoated fruit (control). The addition of the rosehip oil to AV gel reduced respiration rate in all fruit, and ethylene production in the climacteric ones (peaches, plums and nectarine). In addition, all the parameters related with fruit ripening and quality, such as weight loss, softening, colour change and ripening index, were also delayed in treated compared with control fruit, the effect being generally higher when rosehip oil was added to AV, and especially in those fruit that exhibited the highest ethylene production rates (‘Roma’ and flat type peaches). Although the highest effect was obtained with AV+rosehip oil at 10%, the sensory panel detected an excess of gloss and oiliness on the fruit surface, which was considered as a negative attribute. Thus, 2% rosehip oil added to AV could be used as an innovative postharvest tool to increase the beneficial effect of AV as an edible coating, especially in climacteric fruit showing high ethylene production rates.