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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #259924
Title: Effect of maturity and cold storage on ethylene biosynthesis and ripening in ‘Bartlett’ pears treated after harvest with 1-MCP

Author
item VILLALOBOS-ACUNA, MAX - University Of California
item BIASI, WILLIAM - University Of California
item FLORES, SILVIA - University Of California
item Jiang, Cai-Zhong
item REID, MICHAEL - University Of California
item WILLITS, NEIL - University Of California
item MITCHAM, ELIZABETH - University Of California

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2010
Publication Date: 1/1/2011
Citation: Villalobos-Acuna, M.G., Biasi, W.V., Flores, S., Jiang, C., Reid, M.S., Willits, N.H., Mitcham, E.J. 2011. Effect of maturity and cold storage on ethylene biosynthesis and ripening in ‘Bartlett’ pears treated after harvest with 1-MCP. Postharvest Biology and Technology. 59:1-9.

Interpretive Summary: 1-MCP is an ethylene action inhibitor that has been used after harvest to retard ripening in a range of fruits. In pear fruit, 1-MCP treatment has been reported to decrease softening, color development, respiration rates, and ethylene production. California ‘Bartlett’ pears are normally harvested in July and August and cool-stored until they are marketed, generally within 2-3 months to avoid losses due to the development of superficial and senescent scald and internal breakdown. These physiological disorders appear to be ethylene related since treatment with 0.3 µL L-1 1-MCP controls or decreases their incidence even after 5 to 6 months of cold storage at -1°C, which would be considered near maximum storage period for California pears. Although postharvest application of 1-MCP provides valuable benefits, it is challenging to obtain normal softening and ripening in 1-MCP-treated California ‘Bartlett’ pears if the treatment is performed immediately after harvest. The 1-MCP treatment appears to reinforce the natural characteristics of European pears which are resistant to ripening after harvest, and require a period of cold storage or ethylene exposure to induce ripening. Cold storage induces expressions of the enzymes involved in ethylene biosynthesis: ACC synthase (ACS) and ACC oxidase (ACO). Genes encoding putative ACS and ACO sequences have been isolated from pears, but their transcript levels and the identity of those playing a major role during ripening in 1-MCP treated ‘Bartlett’ pears have not yet been described. Fruit maturity and growing region have an effect in the ripening behavior of pears even after ethylene or cold storage treatments and likely can affect 1-MCP response as well. In this study, we test the hypothesis that the induction of ripening in cool storage of 1-MCP-treated pears might be greater in pears harvested at more mature stages. ‘Bartlett’ pears were treated with 0.3 µL L-1 1-MCP for 12 h at 20 °C immediately after harvest in two seasons and to pear fruit of four maturities. 1-MCP decreased rates of softening, ethylene production, respiration, and yellow color development, and reduced incidence of scald and internal breakdown. Ripening recovery induced by cold storage of 1-MCP treated fruit depended on maturity and season and was associated with stimulated ethylene production, including 1-aminocyclopropene carboxylic acid synthase (ACS) activity, 1-aminocyclopropene carboxylic acid oxidase (ACO) activity, and transcript levels of genes associated with these enzymes. The finding of this study strengthens our understanding of the response of ‘Bartlett’ pear fruit to 1-methylcyclopropene (1-MCP) and their ability to recover the capacity to ripen.

Technical Abstract: To further our understanding of the response of ‘Bartlett’ pear fruit to 1-methylcyclopropene (1-MCP) and their ability to recover the capacity to ripen, ‘Bartlett’ pears were treated with 0.3 µL L-1 1-MCP for 12 h at 20 °C immediately after harvest in two seasons and to pear fruit of four maturities. 1-MCP decreased rates of softening, ethylene production, respiration, and yellow color development, and reduced incidence of scald and internal breakdown. Ripening recovery induced by cold storage of 1-MCP treated fruit depended on maturity and season and was associated with stimulated ethylene production, including 1-aminocyclopropene carboxylic acid synthase (ACS) activity, 1-aminocyclopropene carboxylic acid oxidase (ACO) activity, and transcript levels of genes associated with these enzymes.