Presence Of Exogenous Ethylene Research Articles

1-methylcyclopropene prolongs the vase life of roses cv. Osiana

The objective of this study was to determine the effect of 1-methylcyclopropene (1-MCP) on vase life of rose cv. Osiana in different storage conditions and in the presence of exogenous ethylene. The roses were treated with 0.5; 1.0; 1.5 and 2.0 g m-3 of Ethylbloc?, and submitted to the following conditions: Storage at 5 °C with stems in water; Storage at 22 °C with stems in water; Storage at 5 °C in ‘Strong’ type paper for 3 days and subsequent storage at 22 °C. The best storage condition was at 22 °C with the stems in the water. Doses greater than 1.0 g m-3 of Ethylbloc? prolonged vase life. In this condition, the stems were treated with 1.0 g m-³ Ethylbloc?; 1.0 g m-3 Ethylbloc? + 10 ?L L-1 ethylene and 10 ?L L-1 ethylene for 24 h. The Ethylbloc? increased vase life even in the presence of ethylene and fresh mass on the first two days. It reduced ethylene production by flowers in the first 24 h, and respiratory activity after 36 h. It can be concluded that the concentration of 1.0 g m-3 of Ethylbloc? prolongs the vase life of cv. Osiana stored at room temperature with the stems in water even in the presence of exogenous ethylene.

Genome-wide analysis of genes encoding MBD domain-containing proteins from tomato suggest their role in fruit development and abiotic stress responses.

In tomato, DNA methylation has an inhibitory effect on fruit ripening. The inhibition of DNA methyltransferase by 5-azacytidine results in premature fruit ripening. Methyl CpG binding domain (MBD) proteins are the readers of DNA methylation marks and help in the recruitment of chromatin-modifying enzymes which affect gene expression. Therefore, we investigate their contribution during fruit development. In this study, we identified and analyzed 18 putative genes of Solanum lycopersicum and Solanum pimpinellifolium encoding MBD proteins. We also identified tomato MBD syntelogs in Capsicum annum and Solanum tuberosum. Sixty-three MBD genes identified from four different species of solanaceae were classified into three groups. An analysis of the conserved domains in these proteins identified additional domains along with MBD motif. The transcript profiling of tomato MBDs in wild-type and two non-ripening mutants, rin and Nr, indicated constructive information regarding their involvement during fruit development. When we performed a stage-specific expression analysis during fruit ripening, a gradual decrease in transcript accumulation in the wild-type fruit was detected. However, a very low expression was observed in the ripening mutants. Furthermore, many ethylene-responsive cis-elements were found in SlMBD gene promoters, and some of them were induced in the presence of exogenous ethylene. Further, we detected the possible role of these MBDs in abiotic stresses. We found that few genes were differentially expressed under various abiotic stress conditions. Our results provide an evidence of the involvement of the tomato MBDs in fruit ripening and abiotic stress responses, which would be helpful in further studies on these genes in tomato fruit ripening.

Longevity of wild pansy flowers treated with growth regulators

The objective of this study was to evaluate the growth regulators action on the senescence of wild pansy flowers. In the first experiment, floral stems were treated with ethylene for 24 hours at concentrations of 0.1, 1.0, 10, 100 and 1000 μL L-1 and control without the hormone. In a second experiment, the flowers were immersed in solutions of abscisic acid (ABA) containing 5, 20, 50 and 100 μM for one minute and control with water. In a third experiment, 1-methylcyclopropene (1-MCP) was applied at concentrations of 0.5, 1.0 and 1.5 μL L-1 and control without the chemical. In a fourth experiment, 1-MCP and ethylene were applied, where 1-MCP was first applied followed by ethylene. After the treatments with 1-MCP and ethylene, the floral stems were removed from the hermetic chambers and kept in a vessel containing distilled water at 25 °C, 10 μmol m-2 s- 1 white fluorescent light and 50-70% relative humidity as for the ABA treatment. Flowers treated with ethylene did not present significant differences among the concentrations for visual senescence, showing evidence that this flower is not sensitive to ethylene. Treatment with 1000 μL L-1 of ethylene led to a slightly higher fresh weight loss than other treatments, which had a loss of about 33% at end of the experiment. For the ABA treatment, the flowers showed similar fresh weight loss among the different treatments; however, higher concentrations induced slight senescence of flowers. The use of 1-MCP increased the longevity of wild pansy flowers. These results show that 1-MCP is beneficial in maintaining the flower water status, even in the presence of exogenous ethylene, although ethylene may not be directly involved in the senescence of wild pansy flowers.

Action of ethylene and 1-MCP on the quality of nasturtium flowers

The purpose of this study was to determine the effect of ethylene and 1-methylcyclopropene (1-MCP) on the postharvest quality of nasturtium flowers (Tropaeolum majus), by evaluating the mass loss and anthocyanin content of flowers harvested at four different stages of opening. For this, three experiments were performed: only 1-MCP, only ethylene, and 1-MCP combined with ethylene. In both experiments with 1-MCP and ethylene, the flowers were maintained for 24 h with different concentrations of the products. For ethylene, the concentrations used were 0.0, 0.1, 1, 10, 100 and 1000 μL L-1 and for 1-MCP, we used concentrations of 0.0, 0.5, 1.0 and 1.5 μL L-1. For 1-MCP, only the concentration 1.5 μL L-1, was applied for 24 h, then the flowers were exposed to ethylene (100 μL L-1) for a further 24 h, and two controls, inside and outside the airtight chambers. The fourth stage showed the greatest weight loss in response to ethylene at the end of 96 h of assessment in relation to other stages. Ethylene had greater effects on the flowers fully open. In all stages evaluated 'bent neck' effect was observed in response to ethylene, which was inhibited when the flowers were treated with 1-MCP. 1-MCP is effective in preventing the deleterious effects of ethylene, even in the presence of exogenous ethylene. The ethylene at a maximum rate influenced the anthocyanin content, possibly due to greater dehydration of flowers, i.e., greater loss of fresh weight, since the 1-MCP had no influence.

English

The potential of tomato ripening mutants; rin, nor, alc, nr, gr, etc to prolong the shelf life of tomato cannot be overemphasized. Ripening mutants have gained a considerable attention in the last few years to extend shelf life. They have been characterized and examined for their potential utilization in lengthening shelf life of tomatoes. Mutant genes are therefore available to extend the shelf-life of tomato via breeding. These single recessive gene mutants mostly modify ethylene’s downstream effects on specific biochemical processes related to fruit ripening. The fruits of these mutants are characterized by an absence of a ripening-associated ethylene burst and failure to ripen in the presence of exogenous ethylene. They are useful in research and breeding of cultivated tomatoes for postharvest quality. The effect is more pronounced in homozygotes where fruits do not develop normal colour. However, in the heterozygous form, several ripening characteristics exhibit levels that are intermediate between those of the wild and mutant parents and are able to produce fruits that have high shelf life than normal cultivars. Their discoveries have generated insights into ripening control and created new understanding of the primary ripening control mechanisms. Nonetheless, some scientists have argued that these mutant genes produce undesirable pleiotropic effects on other components of fruit quality. This is true in the homozygotes state, however in the heterozygote form, they develop acceptable colour for marketing, ripe naturally and exhibit extended shelf life too. Hence this offers an opportunity to exploit these genes to regulate tomato supply for longer period. Key words: Ethylene, fruit ripening, ripening mutants, shelf life, tomato.

Ethylene and 1-methylcyclopropene action over senescence of nasturtium flowers

ABSTRACT: This work describes ethylene and 1-methylcyclopropene (1-MCP) action on post-harvest shelf life of four development stages of nasturtium flowers. To reach this goal, we carried out three experiments. In the first and second experiments, we studied five ethylene (0; 0.1; 1; 10; 100 and 1000 μL/L) and three 1-MCP concentrations (0.25; 0.5 and 0.75 μL/L), respectively. In the third experiment, 1-MCP was followed by combined with ethylene (only 1-MCP; only ethylene; and 24 hours of exposure to 0.75 μL/L 1-MCP followed by 24 hours of exposure to 100 μL/L ethylene). All experiments had two control treatments, one keeping non-exposed flowers inside and another outside exposure chambers. Experiments were set in factorial design, in complete blocks at random, with four 10-flower replications each. Flower senescence was determined by a pre-established visual scale and by observing floral bud development. Ethylene dose above 10 μL/L induced flower wilting and premature senescence from the second floral development stage. Furthermore, higher concentrations of exogenous ethylene promoted irregular flower opening and/or morphological abnormalities in opened flowers. 1-MCP effectively extended post-harvest longevity of nasturtium flowers, independent of the concentration and even in the presence of exogenous ethylene.

Ethylene promotes induction of aerenchyma formation and ethanolic fermentation in waterlogged roots of Dendranthema spp.

The role of ethylene in induction of aerenchyma formation and ethanolic fermentation in waterlogged roots of Dendranthema zawadskii and D. nankingense, two species that differ with respect to waterlogging tolerance, was examined. In the more tolerant D. zawadskii, but not in D. nankingense, ethylene accelerated programmed cell death and promoted formation of lysigenous aerenchyma, both of which were inhibited by treatment with the ethylene inhibitor 1-methylcyclopropene. Waterlogged D. zawadskii roots generated a higher quantity of endogenous ethylene than did those of D. nankingense. In waterlogged D. zawadskii roots, transcription of the genes encoding alcohol dehydrogenase (EC 1.1.1.1) and pyruvate decarboxylase (EC 4.1.1.1) increased rapidly but transiently, whereas expression of these genes in D. nankingense increased gradually and over a longer period. In D. nankingense, waterlogging elevated both alcohol dehydrogenase and pyruvate decarboxylase activity, and the production of ethanol and acetaldehyde was increased in the presence of exogenous ethylene and inhibited by 1-methylcyclopropene. In D. zawadskii, in contrast, after a prolonged episode of waterlogging stress, exogenous supply of ethylene suppressed the production of ethanol and acetaldehyde, whereas exogenous 1-methylcyclopropene enhanced their production. In the more tolerant Dendranthema species, ethylene appeared to signal an acceleration of both waterlogging-induced programmed cell death and aerenchyma formation and to alleviate ethanolic fermentation, whereas in the more sensitive species ethylene activated fermentation and increased the release of ethanol and acetaldehyde, which are by-products probably responsible for the collapse of the waterlogging-damaged root.

INTRODUCTION OF ETHYLENE INSENSITIVITY IN CAMPANULA CARPATICA FLOWERS BY GENETIC MANIPULATION WITH ETR1-1

The construct containing the etr1-1 gene from Arabidopsis thaliana under control of the flower specific fbp1-promoter from petunia was used to obtain Campanula carpatica Jacq. potted plants with ethylene insensitive flowers. The flowers on the wild type Campanala plants wilted within three days when exposed to 2 μl L -1 ethylene. The tested transgenic etr1-1 lines had various levels of tolerance against ethylene and the best transgenic line continued to flower for up to 27 days in the presence of exogenous ethylene. The expression of etr1-1 in flowers and buds was confirmed by PCR and RT-PCR. The transgenic plants were fertile without any reduction in rooting ability of cuttings, and they did not differ morphologically from the wild type. T1 progeny, a cross between a wild plant and a transgenic plant possessing ethylene insensitive flowers, showed 1:1 segregation in terms of ethylene insensitivity and the presence of the transgene.

Exposure to 1-methylcyclopropene (1-MCP) delays the effects of ethylene on fresh-cut broccoli raab ( Brassica rapa L.)

Broccoli raab florets were treated with 1 μL L −1 of 1-MCP for 24 h at 20 °C and then stored, together with the untreated control, at 5 °C for 14 days in a humidified air flow and air + 100 μL L −1 of ethylene. Treatment with 1-MCP markedly extended the shelf life, reducing postharvest deterioration, retarding chlorophyll degradation, and delaying visual quality loss and flowering, as was also the case with samples stored in the presence of exogenous ethylene. Untreated broccoli raab florets stored either in air or in air + ethylene showed a significant increase in ammonia during storage, suggesting stressful storage conditions. These results indicate that a 1-MCP treatment could be a good candidate for extending shelf life, maintaining visual quality and reducing loss of quality in broccoli raab florets.

Ripening-associated ethylene biosynthesis in tomato fruit is autocatalytically and developmentally regulated

To investigate the regulatory mechanism(s) of ethylene biosynthesis in fruit, transgenic tomatoes with all known LeEIL genes suppressed were produced by RNA interference engineering. The transgenic tomato exhibited ethylene insensitivity phenotypes such as non-ripening and the lack of the triple response and petiole epinasty of seedlings even in the presence of exogenous ethylene. Transgenic fruit exhibited a low but consistent increase in ethylene production beyond 40 days after anthesis (DAA), with limited LeACS2 and LeACS4 expression. 1-Methylcyclopropene (1-MCP), a potent inhibitor of ethylene perception, failed to inhibit the limited increase in ethylene production and expression of the two 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) genes in the transgenic fruit. These results suggest that ripening-associated ethylene (system 2) in wild-type tomato fruit consists of two parts: a small part regulated by a developmental factor through the ethylene-independent expression of LeACS2 and LeACS4 and a large part regulated by an autocatalytic system due to the ethylene-dependent expression of the same genes. The results further suggest that basal ethylene (system 1) is less likely to be involved in the transition to system 2. Even if the effect of system 1 ethylene is eliminated, fruit can show a small increase in ethylene production due to unknown developmental factors. This increase would be enough for the stimulation of autocatalytic ethylene production, leading to fruit ripening.

The effect of CO 2 and 1-methylcyclopropene on the regulation of postharvest senescence of mint, Mentha longifolia L.

The regulatory effects of 5 kPa CO 2 and of the ethylene action inhibitor, 1-methylcyclopropene (1-MCP) at 0.5 μmol/l on the senescence of harvested mint, Mentha longifolia L. were assessed. Visual parameters of senescence including yellowing, browning, decay and leaf abscission were recorded and scored on scales linking the onset and progression of senescence to marketability. The effects of plant age on the rate of postharvest senescence and on the efficacy of the CO 2 and 1-MCP treatments were also investigated. All experiments were repeated with and without the presence of exogenous ethylene. Two experimental formats were used, with 6 days storage at room temperature representing local market conditions, and 6 days cold storage at 1.5 °C followed by 4 days at room temperature representing export market conditions. Sprigs from old plants were no longer of marketable quality after 6 days storage at room temperature. Exogenous ethylene accelerated the onset of senescence causing unacceptably high rates of leaf abscission. Raised levels of CO 2 in a controlled atmosphere system were found to be more effective in inhibiting senescence without the presence of exogenous ethylene than pre-treatment with 1-MCP, and no additive effect was found. However in the presence of exogenous ethylene, a combined treatment with 1-MCP together with raised CO 2 levels resulted in a significant additive effect in nullifying the ethylene-induced leaf abscission. Respiration rates as measured by CO 2 production, and ethylene production, were recorded throughout all experiments. While CO 2 levels were not affected by any experimental treatment, ethylene production was elevated in mint sprigs exposed to an initial dose of gaseous 1-MCP, and was further increased under a combined treatment of 1-MCP together with 5 kPa CO 2. However in the presence of exogenous ethylene, CO 2 strongly suppressed the 1-MCP induced ethylene production.

1-Methylcyclopropene prevents ethylene induced yellowing of rocket leaves

Fully expanded rocket ( Eruca sativa Mill.) leaves were treated with 1-methylcyclopropene (1-MCP, SmartFresh™) at a concentration of 0.5 μl l −1 for 4 h at 10 °C before storage for 10 days in air or in air with ethylene (1 μl l −1). The untreated leaves stored in air showed a progressive yellowing during storage, resulting in a shelf life of about 10 days. The presence of exogenous ethylene in the storage room increased yellowing, and consequently it shortened shelf life by about 2 days. A prestorage treatment with the ethylene action inhibitor 1-MCP prevented yellowing of leaves and shortening of shelf life, which was induced by ethylene.

Co-expression of an ethylene receptor gene, ERS1, and ethylene signaling regulator gene, CTR1, in Delphinium during abscission of florets

We are trying to determine the mechanisms responsible for ethylene-induced floret abscission in cut flowers of Delphinium and recently identified an ethylene receptor gene, ERS1, and studied its response to ethylene treatment. In order to identify additional components of the ethylene response network in Delphinium, we performed 3′ and 5′ rapid amplification of cDNA ends (RACE) using the consensus sequence of the serine/threonine kinase domain of the ethylene signaling regulator gene (CTR1) involved in the constitutive triple response (CTR) to ethylene. The full-length cDNA (2754 nt) encoded a protein of 800 amino acids, which contained the expected serine/threonine kinase domain, the consensus ATP-binding site, and the serine/threonine kinase catalytic site. The protein had quite high (>50%) overall identity to CTR1 from Arabidopsis and tomato, and 70––75% identity in the catalytic site. The amount of mRNA encoding both CTR1 and ERS1 more than doubled within 6 h in cut florets incubated in the presence of exogenous ethylene. Similarly, the amount of ERS1 transcript doubled in florets within 6 d of harvesting, presumably in response to endogenous ethylene, while CTR1 mRNA increased to about 40% over the same period. However, in the presence of silver thiosulfate (STS), an ethylene inhibitor, the level of both transcripts remained essentially unchanged for the first 8 d before declining to very low levels. Florets on the control plants had almost completely abscised by 6 d, but the florets on STS-treated plants had not abscised by 20 d, by which time the flowers were almost dead. The data are consistent with the hypothesis that endogenous ethylene evokes the accumulation of both these transcripts (and their encoded proteins), thereby speeding up abscission and reducing the useful shelf life of the cut flowers.

Effect of octanoic acid on ethylene-mediated processes in Arabidopsis

We have examined whether octanoic acid (OA) one of the short chain saturated fatty acids (SCSFA), increases ethylene response in the following three ethylene-mediated processes: a) hypocotyl growth in darkness; b) formation of new flowers; c) flower abscission. These processes were examined in the presence or absence of exogenous ethylene in Arabidopsis wild type (WT) and in the ethylene-insensitive mutants, etr1-3 and ein2-1 and in the ethylene over-producer mutant eto1-1. Our results show that OA decreased hypocotyl length of WT in the absence or presence of exogenous ethylene, apparently showing that OA acts via augmentation of ethylene action. However, the hypocotyl growth inhibition could not be ascribed to increased ethylene sensitivity since application of inhibitors of ethylene synthesis (aminoethoxyvinylglycine; AVG) or action (1-methylcyclopropene;1-MCP) to WT seedlings did not prevent specifically the OA-induced growth inhibition. Also, OA inhibited hypocotyl growth in the mutants etr1-3 and ein2-1 in a similar pattern to that obtained in WT. On the other hand, OA had no effect on flower formation neither in WT, etr1-3 and eto1-1, in which ethylene reduced flower formation, nor in the ein2-1 mutant, in which ethylene had no effect. OA also did not increase flower abscission in WT or in the mutants etr1-3 and ein2-1 neither in the absence nor in the presence of ethylene. However, OA has augmented flower abscission in the mutant eto1-1 only in the absence of exogenous ethylene. This result might indicate that the effect of OA on eto1-1 is specific to this mutant and is not due to general deleterious effects inflicted by OA. Taken together, our results show that in general OA does not augment ethylene response in Arabidopsis, but it might affect ethylene action in flower abscission of the ethylene-overproducer mutant.

The dual effects of ethylene on the negative gravicurvature of arabidopsis inflorescence, an intriguing action model for the plant hormone ethylene

Ethylene was found to alter the shoot gravitropic response a century ago. However, its actual effects remained controversial over the century. In the present study, we investigated the effects of ethylene on the gravitropic response of Arabidopsis inflorescence and discovered that although the intact Arabidopsis inflorescence bent upward at the rate of 43∘ ±3∘/h in the first 1.5 h under the given control growth conditions, it bent upward at a rate of 20∘±3∘ and 64∘±14∘/h in the presence of exogenous ethylene if the plants were pretreated for 0.5 and 12 h, respectively, before the initiation of gravistimulation. The increase in gravicurvature rate is proportional to the length of ethylene pretreatment. The minimum ethylene pretreatment time required for achieving the maximum curvature rate is 10–11 h with removal of exogenous ethylene. The stimulatory effect of ethylene on the inflorescence gravicurvature requires a latent period of time (1 h) to become measurable. In contrast, the inhibitory effect of ethylene becomes measurable shortly after application of ethylene. The stimulatory effect remained nearly unchanged when the applied ethylene concentration increased from 0.1 to 10 μl/L. However, the inhibitory effect increased substantially as ethylene concentration increased to 10 μL/L. These results suggest that ethylene simultaneously exerts both stimulatory and inhibitory effects on the gravitropic response of the inflorescence, and the stimulatory effect dominates over the inhibitory effect during the interplay between the two in the inflorescence. A “Yin and Yang” action model is hereby proposed to address the interplay between the two effects of ethylene. They may act through distinct signaling pathways.

The influence of exogenous acetaldehyde solution on the vase life of two carnation (Dianthus caryophyllils L.) cultivars in the absence or presence of exogenous ethylene

The effects of acetaldehyde concentration (0, 0.025, 0.05, 0.1, 0.2,0.3, 0.4 or 0.5%) in solution on the vase life and ethylene productionoftwo carnation (Dianthus caryophyllus L.) cultivarscontrasting in vase life (Sandrosa (long lasting) and Yellow Candy (shortlasting)) were studied. In Sandrosa, acetaldehyde solution (0.05%)increased the vase life by 3 days in the absence, or by 2 days in the presence,of exogenous ethylene; the increase in vase life was associated with a delay inthe ethylene climacteric peak. In Yellow Candy, acetaldehyde (0.05%)increased vase life by 3 days, in an ethylene free environment. In the presenceof exogenous ethylene there was no increase in vase life of Yellow Candy.Acetaldehyde failed to inhibit ethylene production in either of the cultivars.It is suggested that acetaldehyde is not involved in the inhibition of ethylenebiosynthesis or sensitivity to ethylene in these two carnation cultivars.

Factors affecting quality and post-production life of Exacum affine

Two cultivars of Exacum affine, White Princess and Royal Dane, were grown under supplementary light conditions (70 and 100 μmol m −2 s −1). The higher light intensity reduced the production time and resulted in increased flower development during the post-production period in an interior environment. To test ethylene responses, the plants were sprayed with the anionic silver thiosulphate complex (STS) and then exposed to 3.5 μl l −1 ethylene or kept in an ethylene-free environment. The post-production quality and life of Exacum plants were reduced by the presence of exogenous ethylene. Inhibition of ethylene action improved post-production flower numbers even in the absence of ethylene.

Chilling-induced leaf abscission ofIxora coccineaplants. II. Alteration of auxin economy by oxidative stress

Chilling-induced leaf abscission of ixora (Ixora coccinea) plants was almost completely inhibited by α-naphthaleneacetic acid (NAA), even in the presence of exogenous ethylene, which enhanced the chilling effect on leaf abscission. Chilling reduced free indoleacetic acid (IAA) content, quantified immediately after chilling, in the abscission zone (AZ) and leaf blade. Free IAA content in chilling-treated plants continued to decrease gradually with time after chilling. Application of the antioxidant butylated hydroxyanisole (BHA) before or after chilling not only prevented the post-chilling decline in free IAA content, but also restored free IAA level during 6–48 h of the post-chilling period almost to the control level. No significant effect of chilling on the endogenous content of ester- and amide-conjugates of IAA or the metabolism of exogenous labeled IAA were observed. Chilling enhanced the decarboxylation of IAA, particularly in the AZ tissue. Auxin transport capacity was significantly inhibited by chilling, and this effect was counteracted by BHA applied before chilling. The data indicate that chilling reduces free IAA content in the AZ, an effect that may lead to increased sensitivity to ethylene. The chilling-induced reduction in IAA content in the AZ seems to result, at least in part, from increased IAA decarboxylation and reduced auxin transport capacity. These processes seem to be triggered by the oxidative stress imposed on the tissues by chilling.

Genetic analysis of ethylene signal transduction in Arabidopsis thaliana: five novel mutant loci integrated into a stress response pathway.

The response of Arabidopsis thaliana etiolated seedlings to the plant hormone ethylene is a conspicuous phenotype known as the triple response. We have identified genes that are required for ethylene perception and responses by isolating mutants that fail to display a triple response in the presence of exogenous ethylene. Five new complementation groups have been identified. Four of these loci, designated ein4, ein5, ein6 and ein7, are insensitive to ethylene. The fifth complementation group, eir1, is defined by a novel class of mutants that have agravitropic and ethylene-insensitive roots. Double-mutant phenotypes have allowed the positioning of these loci in a genetic pathway for ethylene signal transduction. The ethylene-response pathway is defined by the following loci: ETR1, EIN4, CTR1, EIN2, EIN3, EIN5, EIN6, EIN7, EIR1, AUX1 and HLS1. ctr1-1 is epistatic to etr1-3 and ein4, indicating that CTR1 acts after both ETR1 and EIN4 in the ethylene-response pathway. Mutations at the EIN2, EIN3, EIN5, EIN6 and EIN7 loci are all epistatic to the ctr1 seedling phenotype. The EIR1 and AUX1 loci define a root-specific ethylene response that does not require EIN3 or EIN5 gene activity. HLS1 appears to be required for differential cell growth in the apical hook. The EIR1, AUX1 and HLS1 genes may function in the interactions between ethylene and other plant hormones that occur late in the signaling pathway of this simple gas.

Effects of ethephon on the respiration and ethylene evolution of sweet cherry (Prunus avium L.) fruit at different development stages

Abstract The role of ethylene on sweet cherry ( Prunus avium L.) fruit respiration was studied at three stages of development. An ethylene-releasing compound, ethephon [(2-chloroethyl)phosphonic acid], was applied at concentrations from 10 to 1000 ppm to straw-, pink- and mahogany-colored fruits. Depending upon the ethephon concentration applied, rates of ethylene evolution as high 6 μl C 2 H 4 kg fruit −1 h −1 were detected. Ethylene evolution was undetectable from untreated, mature fruits. Fruit respiration rates declined at all stages, regardless of the rate of ethylene evolved. Ethephon did not affect the firmness of mature, mahogany-colored sweet cherry fruit. These results confirm that sweet cherry fruit are nonclimacteric because untreated fruit produced neither respiratory nor ethylene peaks near maturity. Respiration was not stimulated in the presence of exogenous ethylene during these later stages of sweet cherry fruit development, as it is in other nonclimacteric fruits.