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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]

The objective of this study was to investigate the effect of elevated carbon dioxide (CO 2 ) associated with storage room loading on fruit quality and external CO 2 injury in ‘McIntosh’ and ‘Empire’ apples. Effects of fruit cooling rate and the postharvest application of 1-methylcyclopropene (1-MCP) were also evaluated. Over two consecutive years, two strains of ‘McIntosh’ (Pioneer and Summerland) and ‘Empire’ apples were harvested from orchards during the commercial harvest period. In the first year, both strains of ‘McIntosh’ were cooled rapidly to 3 °C and treated with 1-MCP (1 μL L −1 ) overnight. In the second year, half of the apples from each ‘McIntosh’ strain and ‘Empire’ were cooled rapidly to 3 °C, while the other half were cooled slowly from ∼22 °C down to 14–16 °C. All ‘McIntosh’ and half of the ‘Empire’ fruit from each cooling regime were also treated with 1-MCP (1 μL L −1 ) overnight. All apples from both years were then held in ∼17 kPa O 2 + 4 kPa CO 2 , to mimic typical CO 2 build-up during commercial storage room loading, at 3 °C for up to 6 weeks. Overall, Summerland was more susceptible to external CO 2 injury than Pioneer ‘McIntosh’, developing notable symptoms after 4 weeks of storage. 1-MCP treatment increased the incidence of external CO 2 injury in ‘Empire’, regardless of cooling rate. However, 1-MCP-treated ‘Empire’ cooled rapidly developed less external CO 2 injury than those cooled slowly. Other fruit quality attributes (internal ethylene concentration, firmness, soluble solids concentration, and malic acid content) were only marginally affected by short-term holding in elevated CO 2 , in combination with cooling rate and/or 1-MCP treatment. These results suggest ‘McIntosh’ and ‘Empire’ apples are susceptible to developing external CO 2 injury without the establishment of low oxygen and typical controlled atmosphere (CA) storage. Furthermore, slow cooling after harvest may exacerbate the development of external CO 2 injury in apples during storage room loading. [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]

The objective of this study was to investigate the effects of multiple 1-methylcyclopropene (1-MCP) treatments on fruit quality and disorder development in apples, with a second 1-MCP treatment applied after several months of controlled atmosphere (CA) storage. ‘McIntosh’, ‘Empire’, and ‘Northern Spy’ apples were harvested from commercial orchards and cooled overnight to 3 °C. 1-MCP (1 μL L −1 ) was applied 2 d after harvest and then again to half of the fruit after 4 months of CA storage. ‘Northern Spy’ apples also received a single 1-MCP treatment after 4 months of CA storage. Similar fruit from all cultivars were also not treated with 1-MCP. ‘McIntosh’ and ‘Empire’ were held at 3 °C and ‘Northern Spy’ at 0 °C for 9 months in CA storage (2.5 kPa O 2 + 2kPa CO 2 for ‘Empire’, 2.5 kPa CO 2 for ‘Northern Spy’, and 2.5 up to 4.5 kPa CO 2 for ‘McIntosh’). Overall, 1-MCP reduced internal ethylene production, and improved firmness and acidity retention in all apple cultivars. The addition of a second 1-MCP treatment after 4 months of CA storage further improved firmness retention in ‘McIntosh’ and late harvested ‘Empire’ apples after 7 d at room temperature. ‘Northern Spy’ apples treated with 1-MCP had lower incidence of external CO 2 injury, regardless of 1-MCP treatment timing. Multiple 1-MCP treatments had varying effects on the incidence of core browning; late-harvested ‘McIntosh’ treated twice with 1-MCP exhibited the highest incidence of core browning, while late-harvested ‘Empire’ treated twice had less core browning than those not treated. ‘Northern Spy’ treated only at harvest time had more core browning compared to those treated only or also after 4 months of CA storage and non-treated fruit. 1-MCP treatment had no significant effect on the incidence of internal browning in ‘McIntosh’ or ‘Empire’ apples. These results suggest that a second application of 1-MCP after 4 months of CA storage may improve firmness retention in some cultivars during holding at room temperature, but it can also have variable responses associated with susceptibility to disorders, especially when holding apples in long-term CA storage. [ABSTRACT FROM AUTHOR]

1-Methylcyclopropene (1-MCP) is a well-known ethylene action inhibitor that has been applied to fruit after harvest to maintain fruit quality and extend storage life. Recently, the preharvest application of 1-MCP in a sprayable form has been developed and has demonstrated some beneficial effects to prolong harvest window and improve fruit quality. To gain understanding of molecular mechanisms for 1-MCP treatment, as both pre- and postharvest applications on apples, we conducted a quantitative proteomic experiment employing stable isotope labeling by peptide dimethylation on 'Honeycrisp' apples to reveal the significantly changed protein abundance in relationship to fruit quality after preharvest 1-MCP (Harvista™), postharvest 1-MCP treatments as well as their combination. We revealed the treatment affected fruit internal ethylene concentration, fruit quality indices and storage disorders incidence after 7 months of storage at 3 °C. Our quantitative proteomic study identified and quantified more than 600 proteins. Among the identified proteins, 312 proteins were found in common from all treatments, while 141 proteins abundance were changed with regards to preharvest, postharvest and the combination treatments of 1-MCP. We identified a few proteins that were only shown as result of preharvest 1-MCP treatment, while postharvest 1-MCP and in combination with preharvest treatment led to larger number proteins with reduced abundance. These results revealed and confirmed that postharvest 1-MCP and in combination with preharvest 1-MCP treatment affected ethylene biosynthesis, stress resistance, amino acid biosynthesis, antioxidant and redox system metabolisms. Potential metabolic changes resulting from 1-MCP treatment were found, and the efficacy of preharvest 1-MCP treatment was also discussed. [Display omitted] • Pre and postharvest 1-MCP treatments affect fruit quality after storage. • Pre and postharvest 1-MCP treatments affect proteomic changes after storage. • Preharvest 1-MCP treatment had no effect on ethylene biosynthesis and metabolism. • Preharvest 1-MCP treatment enhanced abundance of a few groups of proteins. • Proteomic networks in response to 1-MCP treatments is demonstrated and discussed. [ABSTRACT FROM AUTHOR]