C2H4 Treatment Research Articles

Hydrogen Sulfide Maintained the Good Appearance and Nutrition in Post-harvest Tomato Fruits by Antagonizing the Effect of Ethylene.

Hydrogen sulfide (H2S) could act as a versatile signaling molecule in delaying fruit ripening and senescence. Ethylene (C2H4) also plays a key role in climacteric fruit ripening, but little attention has been given to its interaction with H2S in modulating fruit ripening and senescence. To study the role of H2S treatment on the fruit quality and nutrient metabolism, tomato fruits at white mature stage were treated with ethylene and ethylene plus H2S. By comparing to C2H4 treatment, we found that additional H2S significantly delayed the color change of tomato fruit, and maintained higher chlorophyll and lower flavonoids during storage. Moreover, H2S could inhibit the activity of protease, maintained higher levels of nutritional-related metabolites, such as anthocyanin, starch, soluble protein, ascorbic acid by comparing to C2H4 treatment. Gene expression analysis showed that additional H2S attenuated the expression of beta-amylase encoding gene BAM3, UDP-glycosyltransferase encoding genes, ethylene-responsive transcription factor ERF003 and DOF22. Furthermore, principal component analysis suggested that starch, titratable acids, and ascorbic acid were important factors for affecting the tomato storage quality, and the correlation analysis further showed that H2S affected pigments metabolism and the transformation of macromolecular to small molecular metabolites. These results showed that additional H2S could maintain the better appearance and nutritional quality than C2H4 treatment alone, and prolong the storage period of post-harvest tomato fruits.

Modulation of Enhanced Antioxidant Activity by Hydrogen Sulfide Antagonization of Ethylene in Tomato Fruit Ripening.

Ethylene (C2H4) and hydrogen sulfide (H2S) play important physiological roles in regulating fruit ripening and senescence. The mechanism of H2S in ethylene-induced tomato fruit ripening and senescence is still unknown. Here, we show that exogenous H2S reduced the production of superoxide anion (·O2-), malondialdehyde (MDA), and H2O2 in tomato fruit. Further, additional H2S was found to induce the activities of guaiacol peroxidase, catalase, ascorbate peroxidase, and superoxide dismutase compared with C2H4 treatment alone, whereas the activities of lipoxygenase, polyphenol oxidase, and phenylalanine ammonia lyase were adversely affected. Moreover, the expression of the antioxidant-encoding genes SlAPX2, SlCAT1, SlPOD12, and SlCuZnSOD was generally up-regulated with C2H4-H2S cotreatment, compared with their expression after ethylene treatment. Thus, the present results suggest that exogenous H2S acts as a fruit-ripening regulator by antagonizing the effect of ethylene, thereby providing a potential application for H2S in the postharvest storage of fruit.

Isolation, classification and transcription profiles of the Ethylene Response Factors (ERFs) in ripening kiwifruit

Ethylene is one of the most important plant hormones regulating fruit ripening. In kiwifruit, 14 AdERF genes have been reported, and some members were reported to be involved in fruit ripening and softening. However, a genome-wide investigation of the kiwifruit ERF family was not carried out. Here, 105 novel ERF genes were obtained from the kiwifruit genome. Phylogenetic and MEME analyses indicated that kiwifruit ERF genes are distributed in different subfamilies and all have single AP2/ERF domain. Moreover, some ERF members were putative repressors, as indicated by the presence of EAR motifs. The relationship between the ERF family and kiwifruit ripening we investigated with C2H4 treatment and CA storage. Gene expression analyses pointed out eight ripening related ERF genes, including four putative activators (AdERF10/14/15/75) and four putative repressors (AdERF7/8/19/21) of ripening.

Ripening of tomato fruit locule gel tissue in response to ethylene

Ethylene production by locule gel tissue excised from immature tomato fruit was inhibited by exposure to 4.5 mmol l 1 C2H4, and 1-aminocyclopropane-1-carboxylic acid (ACC) content was reduced. In contrast, CO2 production, ethylene forming capacity (EFC), red colour development, tissue liquefaction and seed maturation as measured by subsequent germination rate were stimulated by C2H4, and, in immature gel, the onset of autocatalytic C2H4 production was hastened. The autoinhibition of C2H4 production in immature locule gel tissue required continuous exposure to C2H4, as transfer to air and then back to C2H4 resulted in C2H4 production first increasing to control levels, then decreasing again. Locule gel tissue from pink fruit however, responded to C2H4 treatment with increased C2H4 and CO2 production, but ACC levels were unchanged. Inhibition of C2H4 action by pretreatment with STS inhibited both autoinhibition and autostimulation of C2H4 production in immature and mature gel tissues, respectively. These results indicate that there is a transition from a negative to a positive feedback mechanism of C2H4 on C2H4 biosynthesis in locule gel during ripening. Control of this feedback mechanism, which involves ACC synthesis, may be separate from that of other manifestations of C2H4 action. © 2000 Elsevier Science B.V. All rights reserved.

513 Simulated Shipment of Fresh-market Tomatoes Utilizing Controlled Atmosphere

Mature-green fresh-market tomatoes (Lycopersicon esculentum Mill.) were held at 11 °C under controlled atmosphere (CA) at 4% O2 and 4% CO2 in a commercial intermodal shipping container equipped with a membrane-based nitrogen-generating CA system. After 4 weeks, tomatoes in CA had 11.9% decay compared to 46.4% decay in control samples held at the same temperature under normal atmosphere. During storage, color development in controls progressed from green to the light red stage in more than 50% of the fruit and only 4.5% remained green after 4 weeks. In contrast, CA stored samples had 25.7% of the fruit in green condition and only 3.9% had progressed to the light red stage. Following CA exposure tomatoes were held at 20 °C with or without 250 ppm C2H4 treatment to observe ripening. All samples ripened normally without symptoms of chilling injury. Results suggest that CA is a useful method for reducing decay and delaying ripening during international transport.

Ethylene Induction of Flowering and Gel Analysis of Apex Proteins in Dutch Iris 'Telstar'

Nonflowering-sized Dutch iris bulbs 'Telstar' were treated at 20 °C in a flow-through system with ethylene-free air or air containing 10 μL.L-1 of ethylene (C2H4) for 1 or 24 hours. Following the treatment, bulbs were placed in a 10 °C cooler for 5 weeks before planting and subsequently forced in a 20 °C day/18 °C night glasshouse. Results demonstrated that a 24-hour C2H4 treatment induced earlier flowering as well as percent flowering. Flowering responses of bulbs treated with C2H4 for 1 hour were the same as those treated with air. The 24-hour ethylene treatment did not affect the combined fresh weight of the daughter bulb and bulblets but reduced the number of bulblets produced by each. The effects of ethylene on the protein changes in the apex were examined at two time periods: immediately after the treatment and after the cold treatment. Each sample consisted of proteins extracted from three apices. There are significant changes in one-dimensional SDS PAGE protein patterns of bulbs apices after treatment with ethylene. However, the differences are apparent after only 1 hour of ethylene treatment. The cold treatment resulted in minimal further changes in protein patterns.

Carambola Quality after Ethylene and Cold Treatments and Storage

Carambolas (Averrhoa carambola L.) must be treated with an approved insect quarantine procedure such as cold treatment before shipment to certain markets. Condition and quality of mature-green (MG) and slightly yellow (SY) fruit were determined after they were: 1) treated with ethylene at 0.1 ml·L-1 for 48 hours (C2H4), 2) subjected to cold treatment (CT) at 1 °C for 15 days, and 3) held in storage at 5 °C for 7 days plus 3 days at 15 °C. Ethylene-treated fruit were softer and yellowness was enhanced compared with non-C2H4-treated fruit. MG fruit were firmer and lost more mass following CT and storage than SY fruit. C2H4 treatment increased the severity of peel scald, stem-end breakdown (SEB), and fin browning but had no effect on pitting. CT increased the severity of scald and pitting, and the severity of SEB, but did not affect fin browning. Peel scald, pitting, SEB, and fin browning were more severe in MG than in SY fruit at the final evaluation. C2H4-treated fruit had lower total soluble solids concentration, higher titratable acidity and pH, and a less preferred flavor and texture than control fruit. We conclude that carambola fruit should be selected at harvest at the slight-yellow stage (3% to 25% of surface area) instead of at the mature-green stage. Fruit to be cold-stored should not be C2H4 treated due to enhanced mold development and severity of SEB.

Effect of Ethylene Treatment on the Occurrence of Bitterness and the Production of a Bitter Compound in Different Tissue of Partially Processed Carrot

The C2H4 treatment induced the occurrence of bitterness and the brown pitting injury in partially processed carrot (PPC) during storage at 20 °C.The pitting injury was more apparent in the inner-phloem than in other tissues. Untreated PPC did not show apparent changes of o-diphenols and isocoumarin. The accumulations of o-diphenols and isocoumarin were greatest in outer- and inner-phloem and were followed by the cambium, cortex and xylem of treated PPC. The C2H4 treatment induced the apparent decrease in non-reducing sugar and the increase in reducing sugar of all tissue.

Quality of Tomatoes Stored at Chilling Temperatures following Prestorage Heat Treatments and Partial Ripening

Mature green `Sunbeam' tomato fruit (Lycopersicon esculentum Mill.), were treated in varying order with C2H4, 42°C water for 60 minutes, 38°C air for 48 hours, partial ripening for 48 hours at 20°C, or not treated, and then stored at 2°C for 14 days before ripening at 20°C. Heat treated fruit stored at 2°C and transferred to 20°C ripened normally while 63% of nonheated fruit decayed before reaching red ripe. More chilling injury (CI) developed when C2H4 was applied following heat treatment rather than before. There was more CI in fruit that were 42°C water treated compared with the 38°C air treatment. Less CI developed on fruit that were partially ripened for 2 days at 20°C before a 42°C water treatment rather than following it. At red ripe, nonchilled fruit were firmer than chilled heat treated fruit. Fruit treated in 42°C water were firmer when the heat treatment was applied before the C2H4 treatment rather than following it. Chlorophyll and lycopene content and internal quality characteristics of fruit were similar at the red ripe stage irrespective of C2H4 or heat treatment. Chilling and heat treatments reduced some of the 15 flavor volatiles analyzed. Volatile levels were lower in fruit treated with C2H4 before heat treatment compared with fruit treated with C2H4 following heat treatment. Prestorage heat treatments could allow for storage of mature green tomatoes at low temperatures with little loss in their ability to ripen normally.

Effect of Ethylene Treatment on the Occurence of Bitterness in Different Parts of Partially Processed Carrot

The occurrence of bitterness, changes in the production of bitter compounds, and sugar contents were measured to determine the effects of ethylene (C2H4) treatment and/or cutting on different tissues (different part of phloem or xylem) of partially processed carrot (PPC) during storage. Carrots (Daucus carota L. var. sativa DC, cv : unknown) were sliced with 1 cm thickness and stored at 20°C with or without C2H4 (100ppm) in air. Phloem or xylem of PPC were divided into three portions (A : part located at 0-1.5mm from cut surface, B : 1.5-3.0 mm, and C : 3.0-5.0), respectively, and the occurrence of bitterness and contents of phenols and sugar in these portions were determined. Neither C2H4-treated nor un-treated PPC showed apparent decay during 3 days of storage, but brown pitting injury on the surface of phloem was markedly associated with C2H4 treatment. This was not so for xylem tissue. The occurrence of bitterness increased apparently in phloem treated with CO2H4 and the xylem was less sensitive than phloem. Bitterness in A was significant and moderate in B and C of phloem. The contents of isocoumarin and phenols, bitter compounds, did not show apparent changes in phloem and xylem of un-treated PPC. The accumulation of these compounds were induced significantly in phloem and moderately in xylem by C2H4 treatment. This increase was greatest in A, followed by B and C in both tissues. An increase in reducing sugar content and a decrease in total sugar content were observed in phloem but not in xylem of C2H4 treated PPC, while neither phloem nor xylem in un-treated PPC showed apparent changes during storage. We conclude that the occurrence of bitterness and the accumulation of bitter compounds in PPC are induced by C2H and cutting and propose the importance of PPC storage without C2H4.

Studies on Physiological and Chemical Changes of Partially Processed Carrot-Part VI. Effects of Cutting Direction, Ethylene Treatment, and Low O2 and/or High CO2 of Atmosphere on the Appearance, Occurrence of Bitterness, and Changes of Sugar Contents in Partially Processed Carrot during Holding.

The C2H4 induced the occurrence of bitterness and the pitting injury and the combination of low O2 (4%) and high CO2 (18%) in the atmosphere suppressed these changes apparently in partially processed carrot (PPC).The PPC showed a decrease in the contents of soluble total sugar (TS) and non-reducing sugar (NRS) and the increase of reducing sugar (RS) by C2H4 treatment during holding at 20°C. The low O2 or high CO2 in the atmosphere delayed the decrease of TS and NRS and the increase of RS induced by C2H4 (20ppm) and the combination of low O2 and high CO2 in the atmosphere suppressed these changes apparently during 5 days holding at 20°C.

RIPENING OF TOMATO FRUIT LOCULE GEL TISSUE

Ethylene production by locule gel tissue excised from full-size immature- and mature-green tomato fruit was inhibited by exposure to l00μl·l-1 C2H4, and ACC content was reduced. In contrast, CO2 production, EFE activity, red color development, and tissue liquefaction were stimulated by C2H4, and, in immature gel, the onset of autocatalytic C2H4 production was hastened. The autoinhibition of C2H4 production required continuous exposure to C2H4, as transfer to air and then back to C2H4 resulted in C2H4 production first increasing to control levels, then decreasing again. Locule tissue from pink fruit responded to C2H4 treatment with increased production of both C2H4 and CO2, but ACC levels were unchanged. Inhibition of C2H4 action by pretreatment with STS inhibited both autoinhibition of C2H4 production in immature gel and autocatalytic C2H4 production in mature tissue. These results indicate that there is a transition from a negative to a positive feedback mechanism of C2H4 on C2H4 biosynthesis in locule gel during ripening. Additionally, this feedback mechanism, which involves ACC synthase, is apparently under separate control from the other manifestations of C2H4 action.

Enhancement of Growth and Flowering of Triteleia laxa by Ethylene

Exposure of dormant corms of Triteleia laxa `Queen Fabiola' to 20 ppm C2H4 for 7 days promoted flowering of small corms and resulted in increased apical meristem size, early sprouting, early flowering, more flowers per Inflorescence, and increased fresh weight of daughter corms and cormels. The respiration rate of the C&treated corms increased to four to five times that of the controls during the 7-day treatment, declined markedly after termination of the C2H4 treatment, but remained higher than that of the controls. The C2H4 effects were associated with increased growth rate and consequently a greater final size of the apical meristem (determined by scanning electron microscopy). Leaves produced by C2H4-treated corms were wider, longer, and weighed more than those of the controls.

Mechanism of Action of Ethylene in Promoting the Germination of Cocklebur Seeds I. Osmoregulation

The germination potentials of upper and lower seeds of cocklebur (Xanthium pennsylvanicum Wallr.) were increased by pre-exposure to water stress imposed by mannitol or polyethylene glycol (PEG) solution. Both types of seeds were responsive to this 'seed priming' which was further enhanced by C2H4 applied exogenously for at least 1 day. The C2H4 effect that occurred during seed priming increased with increasing water stress. It was not influenced by respiratory inhibitors, such as cyanide, azide, benzohydroxymate or propyl gallate, but it was counteracted by CO2 and increased by O2 enrichment. Both C2H4 and O2 significantly increased osmolarity of the sap extracted from the whole seed, but CO2 reduced it. Similar events occurred in seed axial and especially in cotyledonary tissues, and in water extracts of these tissues. Increased osmotic pressure in response to C2H4 stimulated subsequent cotyledonary growth. These findings were applicable also to the action of C2H4 under anoxic conditions, in which the increased potential of seed germination caused by O2 shortage was further enhanced by C2H4 treatment. The higher osmolarities were linked to a stimulation of cotyledonary growth.

Interrelations between Carbon Dioxide and Ethylene on the Stimulation of Cocklebur Seed Germination

Interrelations between CO(2) and C(2)H(4) on promotion of seed germination were examined in more detail at 23 degrees C with presoaked upper seeds of Xanthium pennsylvanicum Wallr. The germination-promoting effect of C(2)H(4) decreased gradually as its application time was delayed during a soaking period, whereas CO(2) was most promotive in application at 5 days of soaking, then its effect declined. CO(2) and C(2)H(4) were additive in earlier soaking periods and synergistic in later periods. Such changes in germination behavior in response to CO(2) and/or C(2)H(4) during a soaking period were closely associated with growth responsiveness of the axial tissues, but not of the cotyledonary ones. Growth responsiveness of axial tissues to CO(2) or C(2)H(4) disappeared finally during a soaking period, but their extinct responsiveness to any one of these gases was almost fully restored in the simultaneous presence of the other. The extinct responsiveness to CO(2) was partially recovered by a preexposure to C(2)H(4). This suggests that in the later period of soaking, unlike the case in a very early period of soaking, the C(2)H(4)-sensitive phase for seed germination precedes the CO(2)-sensitive phase in which CO(2) potentiated axial growth. The restoration of CO(2) responsiveness in axial growth occurred not only after C(2)H(4) treatment but also after exposure to 8 or 33 degrees C or after KCN treatment. Thus, secondarily dormant Xanthium seeds could germinate in response to CO(2) alone, when they were previously exposed for shortterms not only to C(2)H(4) but also 8 degrees C, 33 degrees C, or KCN.

Regulation of Ethylene Production by Ripening Nectarine Fruit as Influenced by Ethylene and Low Temperature

Abstract The rise in C2H4 production during nectarine [Prunus persica (L.) Batsch] fruit ripening at 20°C was accompanied by an increase in the level of 1-aminocyclo-propane-1-carboxylic acid (ACC) and ACC synthase activity. Activity of the C2H4-forming enzyme (EFE) also increased during ripening, but the level was at least 2-times greater than the C2H4 production rate at all stages. C2H4 treatment significantly increased C2H4 production rate, ACC accumulation, and ACC synthase activity. Ability to convert ACC to C2H4, however, was reduced following C2H4 treatment. An increase in total C2H4 production at 20° following storage of nectarines at 0° for up to 4 days was attributable to enhanced ACC synthase activity. Exposure to C2H4 at 0° for more than 4 days reduced C2H4 production and EFE activity during ripening. Increased accumulation of ACC and lowered EFE activity following prolonged C2H4 treatments at 0° suggests that C2H4 production during ripening of fruit held under these conditions is limited by slowed conversion of ACC to C2H4.

Temperature Sensitivity of Avocado Fruit in Relation to C2H4 Treatment

Abstract Avocado fruit (Persea americana Mill. ‘Fuerte’) were stored in air with or without C2H4 treatment (100 ppm) at 6°, 9°, 12°, 14°, 16°, 20°, 24°, 27°, 30°, and 34°C. During the storage period, respiration was measured by an automated continuous gas flow system. Fruit stored in air for more than 20 days at 6° developed chilling injury as indicated by gray discoloration of the mesocarp tissue. At high temperatures (30°, 34°), avocado fruit ripened abnormally, showed considerable surface pitting, and had poor flavor. When fruit were stored with 100 ppm C2H4, tissue discoloration was severe below 12°, which implied that chilling sensitivity of avocado fruit increased with C2H4 treatment. Fruit, whether stored with C2H4 or not, showed breaking points around the same temperature region on an Arrhenius plot, suggesting possible involvement of other mechanisms in addition to phase changes of membrane lipid components.

Preharvest AVG Treatment of ‘Bartlett’ Pear Fruits: Effects on Ripening, Color Change, and Volatiles

Abstract Preharvest treatment with 400 ppm aminoethoxyvinylglycine (AVG) delayed the ripening of ‘Bartlett’ pears kept at 20°C. The effect was not uniform, with the delay in ripening ranging from a few to 112 days. Prolonged storage at 20° was accompanied by a relatively steady, low level of respiration, gradual degreening, and partial suppression of the eventual climacteric. The combined effect of AVG treatment and prolonged ‘nonripening’ storage at 20° led to a marked attentuation of the production of 4 readily measurable volatiles including methyl-, ethyl-, and hexylacetate as identified by cochromatography and combined gas chromatography–mass spectrometry. Surprisingly, prolonged storage resulted in a much increased production of 2 other volatile fractions when AVG inhibition was reversed by C2H4 treatment. The emanation of all measured volatiles was closely coincident with the climacteric peak. These observations confirm prior reports of disuniform effects of preharvest AVG treatment and reveal that metabolic transitions during prolonged, nonripening storage may have adverse effects on fruit quality.

Physiological and Compositional Changes in Orange Fruit in Relation to Modification of their Susceptibility to Penicillium italicum by Ethylene Treatments

Abstract Exposure of orange fruit to 1000 μl/liter C2H4 at 20°C for 2 to 6 days before inoculation with Penicillium italicum Wehmer reduced fungal growth as indicated by lesion diameter and glucosamine content. Respiration rates were stimulated by C2H4 treatments and fungal inoculation, which also increased C2H4 production rate. Ethylene treatments with or without inoculation did not influence soluble solids, pH, titratable acidity, or total phenolics content of fruit juice. Total phenolics of the rind increased in uninoculated fruit, but not in inoculated fruit, in response to C2H4 treatment. No polyphenol oxidase activity was detected. Phenylalanine ammonia-lyase activity exhibited a significant increase in rind of uninoculated fruit, but not in inoculated fruit which were subjected to C2H4 for 6 days followed by 6 days in air at 20°C.

The compartmentation of ethylene in developing cotyledons of Phaseolus vulgaris L.

Isolated cotyledons of Phaseolus vulgaris L. cv. Canadian Wonder accumulated (14)C2H4 (0.7-1 μl l(-1)) from air to give partition coefficients of 1 to 4, which greatly exceeded the value obtained with steam killed cotyledons (0.05) and with water (0.11). After (14)C2H4 treatment, 98% of the (14)C in the tissue remained as (14)C2H4. The labelled ethylene accumulated by cotyledons was released only slowly (1-10% h(-1)) either in an air stream or into toluene. Heating to 60°C for 2 h, but not freezing and thawing, caused the immediate release of (14)C2H4 from the tissue. Propylene and vinyl chloride competitively inhibited the accumulation of (14)C2H4.Cotyledons emanated endogenous ethylene at a very low rate but after heating (although not freezing and thawing) 13 nl of ethylene per g fresh mass were released within minutes. It was concluded that french bean cotyledons hold ethylene in a compartmented form in sufficient amount to account for at least 200 h of emanation.