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Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this study was to investigate the effects of low-oxygen storage and 1-methylcyclopropene (1-MCP) on disorders and quality of 'Empire' apples. For 2 years, 'Empire' apples were obtained from commercial orchards during their harvesting period. After cooling overnight at 3 °C, the apples were treated with or without 1-MCP (1 μL·L-1) for 24 hours and subsequently stored in controlled atmosphere (CA) with 2.5 kPa O2(+2 kPa CO2) or 1.5 kPa O2(+1.2 kPa CO2) for 8 months at 1.5 and 3 °C for the first and second year, respectively. In the second year, a third group of the 'Empire' apples was also held in respiratory quotient (RQ)-based dynamic CA storage (SafePod) that reached 0.6 kPa O2(+0.5 kPa CO2), and half of these apples were treated with 1-MCP (1μL·L-1) for 24 hours at 3 °C upon removal after 8 months. All apples were then evaluated for disorders and quality after 1, 7, or 14 days at room temperature (RT, 23 to 24 °C). Substantial external CO2 injury, flesh browning, and core browning (up to 38% incidence) developed in 'Empire' stored in 2.5 and 1.5 kPa O2during both years of study. Storage in 1.5 kPa O2 reduced flesh browning in the first year and core browning during the second year in apples without 1-MCP, as compared to storage in 2.5 kPa O2. 1-MCP-treated apples stored in 2.5 or 1.5 kPa O2 had higher overall incidence of disorders than similar fruit without 1-MCP. In contrast, there was negligible incidence (0% to 1%) of these disorders in 'Empire' apples held in 0.6 kPa O2, regardless of 1-MCP treatment upon removal. Storage in 0.6 kPa O2 also resulted in the greatest fruit firmness retention while at RT for 14 days. This regime can provide flexibility to postpone 1-MCP treatment until after storage, to prevent increased susceptibility to disorders during storage, without compromising fruit quality. However, results from the RQ-based dynamic CA with 0.6 kPa O2 were from a single season, and further research is needed to confirm these observations. [ABSTRACT FROM AUTHOR]

European pears ( Pyrus communis L.) are stored under low temperatures to extend postharvest life. Unfortunately, senescent scald and internal breakdown are likely to occur with prolonged exposure to storage. Both disorders can be reduced by controlled atmosphere (CA) and/or the ripening inhibitor, 1-methylcylcopropene (1-MCP). The principal aim of this study was to investigate the effect of 1-MCP and CA on fruit quality, including physiological disorders, and oxidative stress metabolites in stored ‘Cold Snap’ and ‘Swiss Bartlett’ pears. Freshly harvested pears were treated with or without 1-MCP, and then stored at 0 °C under refrigerated air or CA (18 kPa or 2.5 kPa O 2 , and 2 kPa CO 2 ) for at least 167 d. 1-MCP and CA delayed and/or reduced the rates of ethylene production in stored fruit of both cultivars. 1-MCP and CA delayed fruit softening and peel yellowing in ‘Swiss Bartlett’ pears, but had negligible to slight effects with ‘Cold Snap’. In both cultivars, high incidences of senescent scald and internal breakdown occurred in non-1-MCP-treated pears during refrigerated air storage. For the most part these symptoms were reduced by CA and 1-MCP, resulting in minimal to negligible incidence in 1-MCP-treated pears stored at 2.5 kPa O 2 . γ-Aminobutyrate accumulated in stored pears, although 1-MCP and CA slightly reduced the levels in ‘Cold Snap’ fruit and 1-MCP increased levels in ‘Swiss Bartlett’ fruit. Ascorbate (total and reduced) levels were rapidly depleted in ‘Cold Snap’ fruit, regardless of treatment; these levels were better maintained in 1-MCP-treated ‘Swiss Bartlett’ fruit than control fruit across all storage atmospheres. In both cultivars, glutathione (total and reduced) concentrations and redox status fluctuated during storage, although these levels were generally higher in 1-MCP-treated fruit. Moreover, glutathione depletion occurred in advance of the development of senescence disorders in stored pear fruit. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this study was to investigate the effects of rapid consecutive 1-methylcyclopropene (1-MCP) treatments on apple quality and disorders in storage. 'McIntosh' and 'Spartan' apples were harvested twice from commercial orchards and 1-MCP (1 µL⋅L-1) was applied postharvest either 1 day after harvest or 1 and 2 days after harvest. Similar fruit from both cultivars were also not treated with 1-MCP, plus an additional treatment of 2 µL⋅L-1 (double rate) I-MCP was used on 'McIntosh'. Fruit were held in either air storage at 0.5 °C for three or six months or in controlled-atmosphere (CA) storage for six or nine months. Overall, 1-MCP treatment improved firmness and acidity retention and reduced internal ethylene in both cultivars. However, 'Spartan' stored in CA often maintained these attributes without 1-MCP. 'McIntosh' apples treated twice with 1-MCP were often firmer than those treated just once. All IMCP treatments substantially reduced superficial scald and there was no difference in scald incidence among the treatments. Core browning was generally reduced by 1-MCP, but fruit treated once with 2 µL⋅L-1 or twice with 1 µL.L-1 1-MCP sometimes had higher incidence than fruit treated only once with 1 µL⋅L-1. 'Spartan' treated twice with 1-MCP also had higher incidence of internal browning after nine months. 1-MCP increased the incidence of external CO2 injury in 'McIntosh' from the first harvest, with fruit treated with 2 µL⋅L-1 having the highest incidence after six months of CA storage and those treated once with 1 µL⋅L-1 having the highest incidence after nine months. Storage rots were greatest after six months of air storage and 1-MCP treatments usually reduced the incidence, regardless of treatment. These results suggest that using more than the traditional single application of 1 µL⋅L-1 1-MCP may improve firmness retention, but there is also some risk associated with increased disorders, especially when storing apples long-term, such as for six months in air or nine months in CA storage. [ABSTRACT FROM AUTHOR]

In combination with low temperature, controlled atmosphere storage and 1-methylcyclopropene (ethylene antagonist) application are used to delay senescence of many fruits and vegetables. Controlled atmosphere consists of low O 2 and elevated CO 2 . When sub-optimal partial pressures are used, these practices represent multiple abiotic stresses that can promote the development of physiological disorders in pome fruit, including flesh browning and cavities, although there is some evidence for genetic differences in susceptibility. In the absence of surface disorders, fruit with flesh injuries are not easily distinguished from asymptomatic fruit until these are consumed. Oxidative stress metabolites tend to accumulate ( e.g. , γ-aminobutyrate) or rapidly decline ( e.g. , ascorbate and glutathione) in vegetative tissues exposed to hypoxic and/or elevated CO 2 environments. Moreover, these phenomena can be associated with altered energy and redox status. Biochemical investigations of Arabidopsis and tomato plants with genetically-altered levels of enzymes associated with the γ-aminobutyrate shunt and the ascorbate–glutathione pathway indicate that these metabolic processes are functionally related and critical for dampening the oxidative burst in vegetative and fruit tissues, respectively. Here, we hypothesize that γ-aminobutyrate accumulation, as well energy and antioxidant depletion are associated with the development of physiological injury in pome fruit under multiple environmental stresses. An improved understanding of this relationship could assist in maintaining the quality of stored fruit. [ABSTRACT FROM AUTHOR]

Controlled atmosphere (CA) storage limits ethylene-related ripening of apple fruit, but can promote the development of CA-related injury. CA-related injury can be exacerbated by the ethylene antagonist, 1-methylcyclopropene (1-MCP). The main objective of this study was to investigate the impact of pre-storage conditioning, 1-MCP and elevated CO 2 on the development of CA-related injury and oxidative stress metabolites in ‘Honeycrisp’ ( Malus × domestica Borkh.) apple fruit. Upon harvest, fruit were treated with or without 1 μL L −1 1-MCP for 24 h, and then transferred to CA (2.5 kPa O 2 and 2.5 kPa or 0.03 kPa CO 2 ) at 3 °C (no conditioning) or conditioned at 10 °C for 5 d prior to CA. Apples were CA-stored for up to 35 weeks. CA-related injury occurred with storage under both CA regimes, regardless of 1-MCP and conditioning, whereas 1-MCP exacerbated the negative impact of elevated CO 2 on this disorder, approximating an 80% incidence, which was coincident with a 400% increase in γ-aminobutyrate (GABA). By comparison, pre-storage conditioning reduced the negative impact of 1-MCP on the incidence of CA-related injury at 2.5 kPa CO 2 by nearly 80%, and this was associated with a dramatically lower GABA concentration. Overall, rapid declines in total ascorbate and ascorbate/dehydroascorbate ratios were evident with storage, regardless of treatment. Transient declines in total glutathione and glutathione/glutathione disulphide ratios were more rapid and sustained for longer periods of time in conditioned than non-conditioned fruit. There were dramatic shifts in the levels of phosphorylated and non-phosphorylated pyridine dinucleotides with storage duration, regardless of treatment, resulting in elevated ratios of NADPH/NADP + and NADH/NAD + after 35 weeks, especially for conditioned fruit subjected to elevated CO 2 . Canonical powered partial least squares analysis revealed that metabolite profiles changed with storage period and treatment, and were most divergent during elevated CO 2 storage. Moreover, CA-related injury was strongly associated with changes in GABA, and moderately linked to total glutathione and glutathione redox status. [ABSTRACT FROM AUTHOR]