Role of ethylene in avocado fruit development and ripening (original) (raw)
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Postharvest Response of Avocado Fruits of Different Maturity to Delayed Ethylene Treatments
PLANT PHYSIOLOGY, 1974
The effect of 10, 100, 1000, 10,000 ppm of ethylene, applied for 3, 6, 12, and 24 hours, on the ripening rate of "Hass" avocado (Persea americana Mill.) fruits at three stages of maturity was investigated. Ethylene treatments were started either immediately after picking or 2 days later. A sharp peak of ethylene production was found to precede full softening by about 2 days and the occurrence of this peak was used to determine ripening rate. Hastening of fruit ripening was much more marked following ethylene treatment which began 2 days after harvesting than immediately after. The difference in response diminished gradually as the fruit became more mature.
Response of Mature Avocado Fruit to Postharvest Ethylene Treatment Applied Immediately after Harvest
1988
Ripening of mature avocado fruit was accelerated by 18-and 24-hr ethylene treatments which were applied beginning 1 hr after harvest. Exposure to ethylene for 12 hr or less, starting 1 hr after harvest, did not accelerate the respiration rate, ethylene evolution, or fruit softening. Ethylene treatment for 6 hr starting at 1, 6, 12, or 18 hr after harvest did not accelerate the onset of the ripening process. It is suggested that ethylene does not just "trigger" the ripening of avocado fruit but rather is involved in a relatively long (18 to 24 hr) process which requires its continuous presence.
Some initial changes in 'Hass' avocado (Persea Americana Mill.) physiology due to ethephon
International Journal of Postharvest Technology and Innovation, 2012
Ethylene is used commercially to hasten ripening of avocados, but the presence of ethylene in the storage atmosphere can increase the risk of physiological disorders. To investigate the short term effect of ethylene on avocado physiology, fruit were dipped in a low concentration ethephon solution. The ethephon treatment significantly increased the ethylene production rate of avocados after 6 h, compared to untreated fruit. After 6 h, the respiration rate of treated fruit increased significantly during the investigation while that of the untreated fruit did not show a significant increase from the initial measurement. Lipid peroxidation increased after dipping, reaching a peak after 4 h, and then declined to a level similar to untreated fruit. Mannoheptulose declined significantly during the 6 h investigation in both the untreated and treated fruit. It is concluded that avocado fruit can undergo significant physiological changes, and quality loss, in a short amount of time, which is exacerbated by exposure to ethylene.
Ethylene regulation of avocado ripening differs between seeded and seedless fruit
Postharvest Biology and Technology, 2010
We studied the contribution of the seed to avocado ripening, emphasizing its role in ethylene biosynthesis and response pathways. Transcription profiles of genes involved in ethylene biosynthesis (PaACO, PaACS1 and PaACS2) and action (PaETR, PaERS1 and PaCTR1) were studied in seeded and seedless avocado fruit during ripening at ambient and low temperatures and in response to exogenous ethylene and 1-methylcyclopropene (1-MCP). Seedless mature fruit had a shorter preclimacteric lag, faster softening, and higher respiration during ambient temperature ripening than seeded ones. Advanced ripening in seedless fruit was accompanied by higher levels of PaACO and PaACS1 expression at harvest, and these levels increased dramatically towards the climacteric peak. The expression of PaETR, PaERS1 and PaCTR1 increased in parallel with the onset of the ethylene burst in seedless fruit, whereas PaETR increase predominantly in seeded ones. Seedless fruit exhibited an earlier response to exogenous ethylene at the day of harvest, than seeded fruit. On day 1 after harvest, ethylene application elicited lower levels of ethylene in seeded than in seedless fruit, concomitantly with massive PaCTR1 augmentation. This suggests that the negative regulator PaCTR may moderate the effect of ethylene on seeded fruit. Cold storage induced biosynthesis and regulatory genes in both seedless and seeded fruit relative to their levels at ambient temperature. However, in the first and second weeks in cold storage, PaACO, PaACS1 and PaACS2 expression levels were much higher in seedless than in seeded fruit, which could explain the higher levels of ethylene and accelerated softening of the seedless fruit in cold storage. Seeded and seedless fruit responded similarly to ethylene or 1-MCP application prior to cold storage. Ethylene slightly induced ethylene production, but significantly increased CO 2 output. 1-MCP equally and effectively delayed softening, reduced ethylene and CO 2 production and expression of genes involved in ethylene biosynthesis and ethylene action in seeded and seedless fruit. Both at ambient temperature and in cold storage respiration was higher in seedless than seeded fruit. Our findings demonstrate that the seed is involved in regulation of ethylene responsiveness during ripening, and acts to delay climacteric in mature seeded fruit.
The plant hormone ethylene has become the focus of plant biology over the last 100 years. It is a gaseous plant hormone that is responsible for fruit ripening, growth inhibition, leaf abscission, aging and a wide range of other plant processes. It is color less gas that is naturally produced by plant and function as a plant growth regulator. In this way ethylene behaves in the same way as hormones in mammals. It triggers specific during plants natural growth and development such as ripening. Though this action it induces changes in certain plant organs such as Texture change, color change and tissue degradation some of this change may be desirable qualities associated with ripening; in other cases it can bring damage or premature decay. Harvesting of Fruits and Vegetables (i.e. Banana and Tomato) may be intentionally or unintentionally exposed to biological active levels of ethylene and both endogenous and exogenous source of ethylene contribute to its biological activity. Ethylene is also at the centre of postharvest technology acting as a key in the extension of shelf life and fruit quality during storage. Ethylene synthesis and sensitivity are enhanced during certain stage of plant development, as well as by a number of biotic and a biotic stresses. Therefore, the main objective of this paper is to review the effects of ethylene on quality of fresh fruit and vegetable.
Role of Ethylene in Fruit Ripening
PLANT PHYSIOLOGY, 1962
There have arisen two schools of thought concerning the role of ethylene in fruit maturation: the classic view of Kidd and West (26) and Hansen (22) that ethylene is a ripening hormone, and a recent interpretation by Biale et al. (7, 3, 4) that it is a by-product of the ripening process. The original presentation of the by-product theory in this journal (7) was tempered with the reminder that 0.1 ppm ethylene may stimulate ripening, so that "in the absence of any information correlating the internal ethylene content with the rate of ethylene production, one can advance the argument that small quantities sufficient to induce ripening are produced prior to the rise of respiration, but measurable amounts are detected only after the onset of the climacteric." The development of highly sensitive gas chromatographic instruments makes it feasible to appraise critically those instances in whiclh fruits have been reported to produce ethylene not at all or only after the climacteric has started, and also to determine the content of ethylene witllin a fruit at the onset of the rise in respiration. Results of such experiments are reported in this communication, and they have a direct bearing on the problem of whetlher or not ethylene is a natural ripening hormone. Materials .Mangoes (Magiiifera indica L., cv. Kent & Haden) were harvested in local orchards. The fruits used for each experiment were picked from the same tree on the same day and were all of about equal size and apparent maturity. Bananas (Miusa acuiiniata cv. Gros Mfichel) harvested at 34 fullness were shipped from Ecuador. Pineapples [Ananas comnosus (L.) AMerr.] at various stages of maturity were flown from Honduras; they arrived in very satisfactory condition w%ithin a day of picking. The Citrus Experiment Station at Tampa, Fla. provided oranges [Citrl(s sinensis (L.) Osbeck] and passion fruits (Passiflora eddlis,Sims); other fruits were purchased in local markets.
2016
Ethylene is a naturally occurring plant growth substance that has numerous effects on the growth, development and storage life of many fruits, vegetables and ornamental crops at ml l1 concentrations. Harvested fruits and vegetables may be intentionally or unintentionally exposed to biologically active levels of ethylene and both endogenous and exogenous sources of ethylene contribute to its biological activity. Ethylene synthesis and sensitivity are enhanced during certain stages of plant development, as well as by a number of biotic and abiotic stresses. Exposure may occur inadvertently in storage or transit from atmospheric pollution or from ethylene produced by adjacent crops. Intentional exposure is primarily used to ripen harvested fruit. The detrimental effects of ethylene on quality center on altering or accelerating the natural processes of development, ripening and senescence, while the beneficial effects of ethylene on quality center on roughly the same attributes as the d...
The role of the embryo and ethylene in avocado fruit mesocarp discoloration
Journal of Experimental Botany, 2009
Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase mesocarp discoloration in seedless fruit stored at 5°C. Application of ethylene to whole fruit induced embryo development inside the seed. It also induced seedling elongation when seeds were imbibed separately. Persea americana ethylene receptor (PaETR) gene expression and polyphenol oxidase activity were highest close to the base of the seed and decreased gradually toward the blossom end. By contrast, expressions of PaETR transcript and polyphenol oxidase activity in seedless avocado fruit were similar throughout the pulp at the base of the fruit. Application of the ethylene inhibitor, 1-methylcyclopropene, decreased mesocarp browning, embryo development, seedling growth, and ion leakage, and down-regulated polyphenol oxidase activity. The results demonstrate that ethylene-mediated embryo growth in whole fruit is involved in the mesocarp response to ethylene perception and the development of CI disorders.
Induction of ethylene in avocado fruit in response to chilling stress on tree
Journal of Plant Physiology, 2009
Chilling of avocado fruit (Persea americana cv. Arad) in the orchard caused a dramatic induction of fruit ripening and a parallel increase in ethylene biosynthesis and receptor genes' expression during shelf life. In-orchard chilling stress stimulated ethylene and CO 2 production already in fruit attached to the tree, and these reduced thereafter during 20 1C storage. In non-chilled control fruit, ethylene and CO 2 production started after 3 d at 20 1C and exhibited a climacteric peak. In-orchard chilling stress also led to membrane destruction expressed as higher electrical conductivity (EC) in chilling stressed (CS) fruit and accelerated softening compared with control fruit. The increase in ethylene production on the day of harvest in CS fruit was accompanied by high expression of two 1-aminocyclopropane-1-carboxylic aCSd (ACC) synthase genes: PaACS1 and PaACS2,a n dA C Co x i d a s ePaACO. The initial gene expressions of PaACS1, PaACS2,a n dPaACO in the CS fruit at the day of harvest was similar to the levels reached by the control fruit after 4 d at 20 1C. The expression levels of both PaETR and PaERS1 in CS fruit on tree were 25 times higher than the control. In control fruit, expression of ethylene receptor genes was very low at harvest and increased in parallel to the onset of the climacteric ethylene peak. PaCTR1 transcript levels were less affected by chilling stress, and small changes (less than 3-fold) were observed in CS fruit on the day of harvest. Together, our results suggest that ethylene biosynthesis and ethylene response-pathway genes are involved in regulation of ethylene responsiveness in response to in-orchard chilling stress and during ripening.
Journal of Food Quality
Avocado production worldwide relies on several varieties, with “Hass” being the most commercialized; however, the available genotypes include a number of green-skin varieties with important roles in several countries. Because many technologies have already been developed in “Hass” avocado, the main objective of this study was to evaluate the effects of controlled atmosphere (CA) storage and 1-methylcyclopropene (1-MCP) application during long-term storage of “Edranol” and “Fuerte” avocados. Fruits of both varieties were harvested at two maturity stages: an early harvest close to 20–23% dry matter (DM) content and another after two months, with 22% and 32% DM content for Edranol and Fuerte, respectively. After harvest, the fruit was stored under the following conditions: (i) regular air storage (RA), (ii) CA with 4% O2 and 6% CO2, and (iii) 1-MCP applied at 300 ppm. Avocados were stored at 5°C and 85% relative humidity. Physiological and quality evaluations were performed immediately...