Delay Ripening Research Articles

Postharvest UV-C treatment combined with 1-methylcyclopropene (1-MCP), followed by storage in continuous low-level ethylene atmosphere, improves the quality of tomatoes

ABSTRACTMature green tomatoes (Solanum lycopersicum L. cv Neang Pich) were exposed to 13.6 kJ m−2 UV-C or 0.5 μL L−1 1-MCP or combination of 13.6 kJ m−2 UV-C and 0.5 μL L−1 1-MCP, with appropriate untreated controls. After treatment, tomatoes were stored in air containing 0.1 μL L−1 ethylene at 20°C and 100% RH. The untreated fruit ripened significantly faster than those of all other treatments. UV-C treatment alone was able to delay fruit ripening by up to 5 days longer compared to untreated fruits whilst the additional of 1-MCP further delayed fruit ripening. UV-C and 1-MCP treatments alone or in combination had significantly slower ethylene production rates throughout the storage period. The fruit treated with the combination of 1-MCP and UV-C was significantly firmer and had higher total phenolic content compared to that of the other treatments. However, there was no difference between treatments in soluble solids content/titratable acids ratio, chlorophyll content, lycopene content and total antioxidant activity. These results show that UV-C and 1-MCP treatment delay ripening and improve the quality of tomatoes in the presence of low-level ethylene during storage. This new treatment could be used to extend the shelf-life of mature green tomatoes through the supply chain without the use of refrigeration.

Effect of Calcium chloride and 1-MCP (Smartfresh™) postharvest treatment on ‘Golden Delicious’ apple cold storage physiological disorders

Calcium (Ca2+) and 1-methylcyclopropene (1-MCP) appear to have opposite effects on the development of bitter pit. However, both post-harvest treatments seem capable of influencing fruit ripening, reducing superficial scald and improving post-storage quality. The objective of this work was to investigate the effect of calcium chloride and 1-MCP alone or combined on the incidence and development of physiological disorders and the delay of ripening of apples during storage (at 0.5°C in air) and subsequent shelf-life at room temperature ≈22°C. ‘Golden Delicious’ apples were harvested in 10 orchards and treated with calcium chloride (1.5%, w/v), 1-MCP (625nLL−1), calcium chloride plus 1-MCP, and without any treatment (control). Physiological disorders and quality parameters were evaluated at harvest and after 6 months storage as well as after 7 d shelf-life. The 1-MCP treatment was effective to prevent superficial scald, slow softening, increase soluble solids content and reduce electrolyte leakage and color changes associated with ripening, during storage and shelf-life. However, this treatment also enhanced the development of bitter pit, especially the moderate and severe symptoms in some orchards, which may be attributable to orchard cultivation techniques. CaCl2 alone and CaCl2 plus 1-MCP reduced bitter pit intensity by reducing moderate and severe incidence, maintained higher lightness and had firmer fruit than control.Postharvest dips of ‘Golden Delicious’ apples in CaCl2 before 1-MCP application (CA+MCP), may be a good solution to prevent scald, and reducing the bitter pit which is enhanced by 1-MCP alone.

Bioactive chitosan based coatings: functional applications in shelf life extension of Alphonso mango – a sweet story

Abstract Chitosan-based coating (M4F2) was used successfully to delay ripening and prolong shelf-life of rapidly perishable and expensive Alphonso mango fruits stored at 30 ± 3°C and 40–50% RH for 15 days. Matured raw Alphonso mango fruits were simple dip treated/coated and air dried with our newly developed chitosan based formulation (for industry) with additives. Samples were taken at regular intervals for routine analysis of fruits. Results indicated that M4F2 coating could decrease the decay incidence loss along with delay the change in color of mango fruit during storage but not physiological steady weight loss. Interestingly, sensory evaluation indicated that quality of mango was enhanced slight significantly to more sweetness and better aroma by M4F2 coating compared to uncoated control fruits. Further, our M4F2 coating formulation may act as an important potentiator of flavor compounds of mango as well as controlling organic acids and sugars, which are key components in the perception of mango flavor. Understanding the chemical components that contribute to flavor perception of the fruit is necessary for post-harvest storage technology. This information is also important to study chitosan/derivatives elicitation in molecular level to improve mango flavor as well as in identification of genes responsible for flavor quality. The scientific story behind this effective chitosan based coating formulation development has been discussed.

Postharvest methyl salicylate treatments delay ripening and maintain quality attributes and antioxidant compounds of ‘Early Lory’ sweet cherry

The effect of postharvest application of methyl salicylate (MeSA) at two concentrations (0.1 and 1mM) on quality attributes, bioactive compounds and antioxidant activity was studied in ‘Early Lory’ sweet cherry. MeSA treatments were effective in reducing respiration rate, weight loss, softening, total acidity losses and the increase in the ripening index during storage at 2°C for 20days as compared with non-treated control fruit. In addition, total phenolics, total anthocyanins and total antioxidant activity (TAA) in the hydrophilic extract (H-TAA) remained at higher concentrations at the end of storage in treated fruit. High correlations were found between H-TAA and phenolics or anthocyanin concentrations and between lipophilic TAA (L-TAA) and total carotenoids. Overall, results demonstrated that MeSA applied as postharvest vapours is an effective and environmentally friendly tool to maintain sweet cherry quality during storage with enhanced bioactive compounds concentration and antioxidant activity.

Effect of post harvest application of chemicals and different packaging materials on shelf-life of banana (Musa spp) cv Robusta

An experiment was conducted in Department of Horticulture (Fruit and Fruit Technology), Bihar Agricultural College, Sabour, Bihar during 2010-11 to delay ripening and extend shelf-life of banana (Musa paradisiaca L.) fruit. The experiments were undertaken with twelve treatments combinations of CaCl2 (2% or 4%), polyethylene bag, banana dried leaves, newspaper, CaCl2 (2%) + polyethylene bag, CaCl2 (4%) + polyethylene bag, CaCl2 (2%) + banana dried leaves, CaCl2 (4%) + banana dried leaves, CaCl2 (2%) + newspaper, CaCl2 (4%) + newspaper and control. CaCl2 (4%) and CaCl2 (2%) in combination with polyethylene bag were the most potent treatment for enhancing storage period and maintaining physico-chemical characteristics of banana cv Robusta while as CaCl2 (4%) + polyethylene bag were very effectively reduced physiological loss in weight (PLW) and ripening per cent. The maximum retention of bio-chemical constitute like total soluble solids, titratable acidity, and reducing sugars was also obtained in fruits treated with CaCl2 (4%) + polyethylene bag along with increased shelf-life up to 16th day storage period of banana fruits.

Aqueous 1-Methylcyclopropene to Delay Ripening of ‘Kent’ Mango With or Without Quarantine Hot Water Treatment

Gaseous 1-methylcyclopropene (1-MCP) delays mango (Mangifera indica) fruit ripening, but requires 12 hours of application in sealed containers. In some fruit species, aqueous formulation applied as a postharvest dip for only 1 to 5 minutes has shown the same effectiveness as gaseous 1-MCP. This research was conducted to determine the effectiveness of aqueous 1-MCP on delay of the ripening process, extension of shelf life, and maintenance of fruit quality of ‘Kent’ mango fruit with or without quarantine hot water treatment (QHWT). Three experiments were conducted during the 2013 season in Mexico and Florida and during the 2014 season in Mexico. Aqueous 1-MCP caused delay of fruit ripening as shown by maintenance of fruit firmness, attenuation of flesh color development, and delayed increase of total soluble solids (TSS). However, it had a negative interaction with QHWT, causing surface spots and lenticel blackening to develop during shipping simulation [3 weeks at 12 ± 1 °C, 90% ± 5% relative humidity (RH)] and market simulation (7 days at 22 ± 2 °C, 75% ± 10% RH). This negative interaction was less when 1-MCP was applied before QHWT, somewhat higher when 1-MCP was applied after QHWT, and most severe when 1-MCP was applied after QHWT + hydrocooling. By contrast, the ripening of fruit treated with 1-MCP without QHWT was delayed without affecting external appearance. Thus, 1-MCP may be more useful for mango markets that do not require mandatory QHWT.

RNA sequencing and functional analysis implicate the regulatory role of long non-coding RNAs in tomato fruit ripening.

Recently, long non-coding RNAs (lncRNAs) have been shown to play critical regulatory roles in model plants, such as Arabidopsis, rice, and maize. However, the presence of lncRNAs and how they function in fleshy fruit ripening are still largely unknown because fleshy fruit ripening is not present in the above model plants. Tomato is the model system for fruit ripening studies due to its dramatic ripening process. To investigate further the role of lncRNAs in fruit ripening, it is necessary and urgent to discover and identify novel lncRNAs and understand the function of lncRNAs in tomato fruit ripening. Here it is reported that 3679 lncRNAs were discovered from wild-type tomato and ripening mutant fruit. The lncRNAs are transcribed from all tomato chromosomes, 85.1% of which came from intergenic regions. Tomato lncRNAs are shorter and have fewer exons than protein-coding genes, a situation reminiscent of lncRNAs from other model plants. It was also observed that 490 lncRNAs were significantly up-regulated in ripening mutant fruits, and 187 lncRNAs were down-regulated, indicating that lncRNAs could be involved in the regulation of fruit ripening. In line with this, silencing of two novel tomato intergenic lncRNAs, lncRNA1459 and lncRNA1840, resulted in an obvious delay of ripening of wild-type fruit. Overall, the results indicated that lncRNAs might be essential regulators of tomato fruit ripening, which sheds new light on the regulation of fruit ripening.

English

The optimum condition for storage of 'Laetitia' plums (Prunus salicina) under controlled atmosphere (CA) is not currently known. This study was aimed at assessing the effects of controlled atmospheric (CA) conditions on the postharvest quality preservation of ‘Laetitia’ plums. Besides regular atmosphere (RA; 21kPa O2 + 0.03 kPa CO2) as condition/treatment control, the following CA conditions (kPa O2 + kPa CO2) were assessed: 1+3; 1+5; 2+5; 2+10; and 11+10. In all cases, the fruit were stored for 60 days at 0.5°C±0.1°C and 96±2% of relative humidity (RH). Upon removal from the cold storage chamber and after four days in ambient conditions (20±2°C/60±5% RH), the fruit were assessed in terms of: respiration and ethylene production rates; flesh firmness; texture; titrable acidity; red color index and hue angle (ho) of the skin; incidence of fruit cracking and internal breakdown (flesh browning). The fruit stored under the different CA conditions presented lower respiration and ethylene production rates, higher values of flesh firmness, texture and titrable acidity, lower development of skin red color, and lower incidence of skin cracking compared to the fruit under RA. CA conditions of 2+5, 1+5, and 1+3 resulted in a more substantial delay of ripening. CA conditions of 2+5 and 1+3 resulted in lower incidence of internal breakdown. Key words: Ripening, physiological disorder, postharvest, Prunus salicina.

Reduction of postharvest anthracnose and enhancement of disease resistance in ripening mango fruit by nitric oxide treatment

Nitric oxide (NO) acts as an important signal molecule with diverse physiological functions in plants. In this study we investigated the effects and possible mechanisms of exogenous NO on anthracnose caused by Colletotrichum gloeosporioides in mango fruit. ‘Guifei’ mango fruit were treated with NO donor (sodium nitroprusside of 0.1mM) at 25°C for 5min, inoculated with spore suspension of C. gloeosporioides after 24h of NO treatment, and stored at ambient temperature (25°C). NO treatment effectively suppressed lesion development on mango fruit inoculated with C. gloeosporioides, and lesion diameters at 2 through 8d in NO-treated fruit averaged 30% lower than those in control fruit. Additionally, NO treatment reduced natural anthracnose incidence and severity of mango fruit ripened at ambient temperature, and the values of both parameters from 4 to 10d of storage in NO-treated fruit averaged 40 and 45% lower, respectively, than those for control fruit. NO did not exhibit in vitro antifungal activity against C. gloeosporioides. NO treatment enhanced the activities of defense-related enzymes including phenylalanine ammonia-lyase (PAL), cinnamate-hydroxylase (C4H), 4-coumarate: CoA ligase (4CL), peroxidase (POD), β-1,3-glucanase (GLU) and chitinase (CHT). NO treatment also promoted the accumulation of total phenolics, flavonoids and lignin that might contribute to inhibition of the pathogen. In addition to antifungal efficacy, NO treatment delayed flesh softening, yellowing, and changes in soluble solids content (SSC) and titratable acidity (TA), and peaks of respiration rate and ethylene production during ripening. These results suggest that the resistance of NO-treated mango to anthracnose may be attributed to activation of defense responses as well as delay of ripening.

Ripening and sensory analysis of Guatemalan-West Indian hybrid avocado following ethylene pretreatment and/or exposure to gaseous or aqueous 1-methylcyclopropene

Previous reports showed that both gaseous and aqueous 1-methylcyclopropene (1-MCP) delay ripening of avocado (Persea americana Mill.), but there are no reports of the influence of 1-MCP on its sensory attributes. The objective of this study was to evaluate the effects of ethylene pretreatment and/or exposure to gaseous or aqueous 1-MCP on fruit ripening and sensory attributes of ‘Booth 7’ avocado, a Guatemalan-West Indian hybrid. Separate experiments were conducted during two seasons (2008 and 2009) with fruit harvested at preclimacteric stage in October (early season) and in November (late season). Fruit from Season 1 were exposed to ethylene (4.07μmolL−1) for 12h at 20°C, and stored for more 12h at 20°C in an ethylene-free (ethylene, <0.1μLL−1) room prior to treatment with either aqueous (1.39 or 2.77μmolL−1 a.i.) or gaseous (3.15 or 6.31nmolL−1 a.i.) 1-MCP. Ripening was monitored and firmness, respiration, ethylene production and weight loss were measured. Texture profile analysis and sensory analysis were performed on ripe fruit only (firmness, 10–15N). Fruit from Season 2 were not exposed to ethylene pretreatment but treated only with aqueous 1-MCP 24h after harvest. Fruit were assessed exclusively for sensory analysis when ripe (firmness, 10–15N). Treatment with either 1-MCP formulation effectively delayed ripening from 4 to 10d for early-season fruit, and from 4 to 6d for late-season fruit. Higher concentrations of 1-MCP of either formulation had the greatest effect on selected pulp textural parameters of early-season fruit; the gaseous formulation had greater effect on late-season fruit quality than the aqueous formulation. In general, sensory panelists ratings of overall liking were not affected by 1-MCP treatment. Both aqueous and gaseous 1-MCP formulations delayed ripening of the Guatemalan-West Indian ‘Booth 7’ avocado without significant loss in appearance or in sensory attributes and, therefore, could be considered for use as a postharvest treatment for this hybrid.

Behavioral Pattern of Physicochemical Constituents of the Postharvest Mango (Mangifera indica L.) Influenced by Storage Stimuli

An investigation was carried at the laboratory of the Department of Biochemistry and Molecular Biology, University of Rajshahi, Bangladesh during the period from May, 2010 to September, 2011 to study the behavioral pattern of some physicochemical constituents of the mango pulp. The experiment was comprised of two popular mango cultivars in Bangladesh (viz., Langra and Khirshapat) and six storage stimuli, namely control, paraffin coating, perforated polyethylene cover, unperforated polyethylene cover, hot water (55 +/- 1 degree C) and low temperature (4 +/- 1 degree C). The two factors experiment was assigned in randomized complete block design with tree replicates. The varieties had profound variation in terms of most of the characters studied in the laboratory condition. Initially the Langra significantly enriched a greater amount of vitamin C (151.23 mg/100 g) and titratable acidity (4.31%) and these were decreased gradually with the progress of storage period. The Khirshapat showed higher pulp pH (5.83); produced enormous amount of TSS (18.00%) and sugar (TS = 17.62%, RS = 6.51% and NRS = 11.06%) content at 12th day of storage. The pH, TSS, sugar (TS, RS and NRS) content of mango pulp was rapidly increased, whereas vitamin C and titratable acidity decreased drastically from the untreated mangoes. On the other hand, low temperature retarded the changes. The Langra using low temperature (4 +/- 1 degree C) exhibited lower diminishing tendency in vitamin C and titratable acidity and also using no treatment slightly increased TSS; enriched enormous amount of sugar (TS, RS and NRS). Therefore, low temperature (4 +/- 1 degree C) was found satisfactory for delay ripening and postharvest changes of mango in storage condition.

Effects of Se-enrichment on yield, fruit composition and ripening of tomato (Solanum lycopersicum) plants grown in hydroponics

Selenium appears to be effective in promoting plant development and delaying the onset of senescence. Besides the effects on the metabolism and physiology of different crops, controlled increases in Se concentrations enhance the health-related properties of the produce. To study the effects of selenium on fruit composition and ripening physiology, an experiment was carried out on tomato (Solanum lycopersicum) plants grown in hydroponics. Sodium selenate was added to the nutrient solution at a rate of 0 (control) and 1mgSeL−1. The selenium added to the nutrient solution was absorbed by the roots, and the Se concentration was higher in leaves than in fruits. The addition of Se did not significantly influence the cumulative yield of tomato plants, but a delay in the onset of fruit ripening was detected, and the harvesting of control plants began earlier than in Se-treated plants. The addition of Se did not significantly affect the qualitative parameters with the exception of β-carotene content, which was lower in red ripe fruit treated with selenium. Since β-carotene accumulation is a ripening-related event in tomato, the lower amount of this compound may be associated with a general delay of ripening. This is confirmed by the reduced biosynthetic rate of ethylene, observed in Se-treated tomatoes, which also showed a reduced rate in colour change. This thus confirmed that ripening-related processes, such as the degradation of chlorophyll and the synthesis of carotenoids, are affected by selenium - with potential benefits in terms of storage and shelf-life. Our results showed that 100g of tomato hydroponically grown with a nutrient solution supplemented with Se provided a total of 58μg Se. Thus, the daily consumption of 100g of enriched tomato does not lead to Se toxicity, but can even provide a rational Se supplementation. This suggests that the addition of Se in a nutrient solution is useful for producing tomatoes with greater beneficial properties for human health.

CFD-Based Analysis of 1-MCP Distribution in Commercial Cool Store Rooms: Porous Medium Model Application

1-Methylcyclopropene (1-MCP) is a synthetic plant growth regulator used commercially to delay ripening of fruits. 1-MCP (SmartFreshTM) is applied in gaseous form (as a fumigant) in the cool store room. This paper uses a porous medium computational fluid dynamics model to numerically analyze the distribution of 1-MCP in cool store rooms for apple fruit. The effects of air circulation, room shape, and bin material were investigated. Dose calculation based on filling density was explored. The 1-MCP distribution in commercial cool stores, under room cooling condition, was uniform irrespective of room shape. Rooms filled with fruit in wooden bins deplete 25 % more of the active substance than rooms filled with fruit in plastic bins. The calculated dose increases linearly with the amount of fruit in the cool store (filling density). Hence, this study suggests that dose prescription based on filling density is feasible.

Chlorine dioxide treatment decreases respiration and ethylene synthesis in fresh‐cut ‘Hami’ melon fruit

SummaryThe effects of chlorine dioxide (ClO2) on respiration and ethylene synthesis of fresh‐cut melon fruit and the possible mechanisms involved were investigated. Fresh‐cut ‘Hami’ melon fruit fumigated with gas ClO2 in sealed container for 12 h and then stored at 5 °C with 95% relative humidity (RH) for 19 days. Results showed that fruit treated with ClO2 resulted in lower rates of the total respiration, alternative pathway respiration, cytochrome pathway respiration and ethylene production. Furthermore, the expressions of ethylene biosynthesis‐related genes, including CmACS2, CmACO1 and CmACO3 were reduced by ClO2 treatment. Taken together, it is suggested that ClO2 treatment might be an effective way to delay ripening of fresh‐cut ‘Hami’ melon, partially due to the reduced respiration and ethylene biosynthesis.

Effect of box materials on the distribution of 1-MCP gas during cold storage: A CFD study

1-Methylcyclopropene (1-MCP) is a synthetic plant growth regulator used commercially to delay ripening of fruits. The substance is applied in gas form (as a fumigant) in the storage room. In long term postharvest cold storage, fruit are placed in boxes (usually plastic or wooden bins) and stacked in a specific pattern. The top of the boxes are frequently covered with a thin plastic sheet for the purpose of reducing fruit moisture loss. Wooden boxes, card linings and other plant based porous materials used in bins have 1-MCP adsorption capacity. Plastic covers affect the airflow and with that the 1-MCP transport. In this paper, the influence of box materials and plastic cover on the distribution of 1-MCP in cold storage was studied using validated CFD models. Reynolds Average Navier–Stokes equations with the SST k–ω turbulence model were used to calculate the airflow. Diffusion, convection and adsorption of 1MCP were modeled to obtain 3D spatial and temporal distributions of 1-MCP inside a storage container, boxes and fruit. Time dependent profiles of calculated 1-MCP concentrations in the air in the container agreed well with measurement data. The plastic cover imposed no effect on the adsorption of 1-MCP. Wooden boxes notably adsorbed 1-MCP from the treatment atmosphere and may reduce the efficacy and uniformity of the treatment.

Delay Ripening Treatments to Maintain Quality of Lime Fruit (Citrus aurantifolia) In Two Different Harvest Time

In Indonesia lime is a widely consumed and economically significant crop. Lime would be harvest when development of fruit is optimum but still have greenish peel color ( Murata, 1997 ; Thompson, 2003). Customers tend to prefer lime fruit that is green instead of yellow (Thompson, 2003). The main problem of lime is yellowing. The most visible is loss of peel greenness that usually cause by Chlorophyll degradation (Drazkiewice, 1994; Srilaong et al., 2011). The prevention of the degradation of chlorophyll can be done by way of delay maturity, such as by using a hot water treatment, KmnO4, and waxing. The result showed that delay ripening treatments could maintain physical and chemical quality of lime fruit during storage compared with control. The treatments also could prolong the shelf life of fruit up to 20 days after treatment, compared with control which only reaches 15 days. HWT 40 o ;2mnt;6 mafi s the best treatment in every parameters, include chlorophyll content 1.94 mg/l, weight loss 2.30 %, vitamin C 59 mg/100ml, total acidity 0.76 %, and juice content 19 ml. Time harvest 6 months after flowering has the ability to maintain physical and chemical quality

APPLICATIONS OF BIOTECHNOLOGY TO TROPICAL FRUIT CROPS IN QUEENSLAND, AUSTRALIA

Tropical fruits play an important role in the economy of Queensland. The major crops are banana, mango, pineapple and papaya. For the past 20 years, biotechnology has been applied to tropical fruit species in Queensland. Micropropagation systems have been developed for banana, pineapple, papaya, passionfruit and coffee; and good embryogenic protocols have been employed in banana, mango and papaya. A program of intergeneric hybridisation between papaya and related Vasconcella species has continued since 1991 and has been facilitated by embryo rescue and plantlet production, and micropropagation in vitro. Cryopreservation protocols are being developed for several tropical fruit species. Transformation systems have been used to produce disease resistant genotypes of papaya and to prevent blackheart, to control flowering and delay ripening of pineapple. Molecular marker technology has been used for genotype identification and to confirm intergeneric hybrids between papaya and related Vasconcella species. Molecular maps have been developed for two Vasconcella species. Genetic diversity within mangosteen populations and between related wild species has been evaluated with RAF markers. Specific DAF markers have been identified for sex determination in papaya, and SCAR markers have been developed to identify dwarfism in bananas and the PRSV-P resistant gene in Vasconcella cundinamarcensis.

Manejo do etileno durante o armazenamento de ameixas 'Laetitia' em atmosfera controlada

Objetivou-se avaliar o efeito da aplicação de 1-metilciclopropeno (1-MCP) e de diferentes concentrações de etileno sobre a qualidade de ameixas 'Laetitia' armazenadas em atmosfera controlada (AC). Os tratamentos utilizados foram aplicação de 1-MCP (1,0µL L-1) e etileno (C2H4) nas concentrações de &lt;0,04µL L-1, 1,0µL L-1 e 10µL L-1 no interior das câmaras de AC (1,0kPa de O2+3,0kPa de CO2 / 0,5°C±0,1°C e UR de 95±2%). A taxa respiratória foi menor nos frutos tratados com 1-MCP e armazenados com 10µL L-1 de C2H4. A produção de etileno foi menor nos frutos tratados com 1-MCP. Na saída da câmara, os frutos tratados com 1-MCP ou armazenados com &lt;0,04µL L-1 de C2H4 apresentaram maior firmeza de polpa, resistência do fruto à compressão e menor incidência de degenerescência da polpa. Após quatro dias de exposição dos frutos em condição ambiente, a maior firmeza de polpa ocorreu nos frutos tratados com 1-MCP. A acidez titulável foi maior nos tratamentos 1-MCP e &lt;0,04µL L-1 de C2H4. A aplicação de 1-MCP e a absorção de etileno retardam o amadurecimento da ameixa 'Laetitia' e diminuem a incidência de degenerescência da polpa, sendo que o efeito do 1-MCP se prolonga durante o período de prateleira. Contudo, mesmo com o uso dessas tecnologias, a incidência de degenerescência de polpa não permite o armazenamento por 60 dias, na condição de AC utilizada.

Genetic dissection of the role of ethylene in regulating auxin-dependent lateral and adventitious root formation in tomato

In this study we investigated the role of ethylene in the formation of lateral and adventitious roots in tomato (Solanum lycopersicum) using mutants isolated for altered ethylene signaling and fruit ripening. Mutations that block ethylene responses and delay ripening -Nr (Never ripe), gr (green ripe), nor (non ripening), and rin (ripening inhibitor) - have enhanced lateral root formation. In contrast, the epi (epinastic) mutant, which has elevated ethylene and constitutive ethylene signaling in some tissues, or treatment with the ethylene precursor 1-aminocyclopropane carboxylic acid (ACC), reduces lateral root formation. Treatment with ACC inhibits the initiation and elongation of lateral roots, except in the Nr genotype. Root basipetal and acropetal indole-3-acetic acid (IAA) transport increase with ACC treatments or in the epi mutant, while in the Nr mutant there is less auxin transport than in the wild type and transport is insensitive to ACC. In contrast, the process of adventitious root formation shows the opposite response to ethylene, with ACC treatment and the epi mutation increasing adventitious root formation and the Nr mutation reducing the number of adventitious roots. In hypocotyls, ACC treatment negatively regulated IAA transport while the Nr mutant showed increased IAA transport in hypocotyls. Ethylene significantly reduces free IAA content in roots, but only subtly changes free IAA content in tomato hypocotyls. These results indicate a negative role for ethylene in lateral root formation and a positive role in adventitious root formation with modulation of auxin transport as a central point of ethylene-auxin crosstalk.

Delay ripening of ‘Qingnai’ plum ( Prunus salicina Lindl.) with 1-methylcyclopropene

‘Qingnai’ plum fruit were treated with 0, 250, 500 or 1000 nL L −1 of 1-methylcyclopropene (1-MCP) for 6 h and stored at 20 °C. The fruit firmness, peel color, chlorophyll content, titratable acidity (TA), respiration rate and ethylene production, chlorophyllase, pectin methylesterase (PME) and polygalacturonase (PG) activities were monitored during postharvest ripening of ‘Qingnai’ plums. ‘Qingnai’ plums without 1-MCP treatment soften very rapidly at room temperature after harvest, showing a continuing decrease in hue angle, chlorophyll content, TA and increase in chlorophyllase, PME and PG activities during postharvest storage. In contrast, the 1-MCP-treated fruits showed reduced ethylene production and respiration rate and delayed softening, which was associated with the reduction in the activity of PME and PG. The 1-MCP treatment also significantly inhibited the chlorophyllase activity and peel color development in ‘Qingnai’ plums during postharvest ripening at 20 °C. These results suggest that 1-MCP treatment may be useful for maintaining the fruit quality and extending the postharvest shelf-life of ‘Qingnai’ plums.