Metabolic and Other Responses of 'Bartlett' Pear Fruit and Suspension-cultured 'Passe Crassane' Pear Fruit Cells Held in 0.25% O2
| Autor: | Adel A. Kader, George D. Nanos, Roger J. Romani |
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| Rok vydání: | 1992 |
| Předmět: | |
| Zdroj: | Journal of the American Society for Horticultural Science. 117:934-940 |
| ISSN: | 2327-9788 0003-1062 |
| Popis: | Bartlett' pears (Pyrus communis L.) that had been stored for either 2 or 8 weeks in air at 0C were placed under an atmosphere of 0.25% 0, (balance N2) at 20C for 4 days then returned to air. Control pears were kept in air at 20C. Suspension-cultured 'Passe Crassane' pear fruit cells in aging medium were treated similarly. During exposure of the fruit to 0.25% O2, loss of greenness and ethylene production were inhibited and CO 2 production substantially decreased. Pears that had been stored for 2 weeks at 0C ripened normally, while those that had been stored for 8 weeks at 0C failed to recover normal ethylene and CO 2 production upon transfer to air after a 4-day exposure to 0.25% O2 at 20C. Most of the latter fruit were injured as indicated by skin browning. Acetaldehyde and ethanol content increased considerably with ripening of control fruit. Although 0.25% O 2-treated fruit developed yet higher acetaldehyde and ethanol contents during treatment, the concentrations returned to or below normal during subsequent exposure to air. Pears exposed to 0.25% 0, had increased pyruvate decarboxylase (PDC; EC 4.1.1.1) and alcohol dehydrogenase (ADH; EC 1.1.1.1) activities that remained high after ripening in air for 6 days. Three ADH isozymes were discernible in the 0.25% O2-treated pears, whereas only one, ADHZ, was found in control fruit. These observations imply that preclimacteric pears are both less stressed during hypoxia and have greater potential for posthypoxia repair than pears of a more advanced physiological age. Increased posthypoxia respiratory and enzymatic activity and the elaboration of new ADH isoenzymes appear to be part of the repair response. Suspension-cultured pear fruit cells responded to the atmospheric changes very much like the S-week stored fruit and likely is a good model system to further study the effects of hypoxia on pear metabolism. Storage in low-O 2 atmospheres at or near OC is a common practice that delays chlorophyll loss, softening, and ripening of many horticultural commodities (Kader, 1986). However, for insect control, low O2 treatments are more effective at higher temperatures. Even relatively short exposures of fruits to O 2 levels |
| Databáze: | OpenAIRE |
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