1-Methylcyclopropene Pretreatment in ?La France? Pears to Extend Postharvest Life and Maximize Fruit Quality

A major challenge in terms of commercializing 1-methylclopropene (1-MCP) to extend the storage life and control physiological disorders in European pears is that it irreversibly inhibits fruit ripening in some cultivars, particularly flesh softening that is necessary for optimal consumption quality. In this study, we examined the effect of 1-MCP pretreatments on fruit ripening and associated transcriptomic changes in 'La France' (Pyrus communis L.) pears during storage at 20 degrees C and 5 degrees C. Compared to non-treated controls, 1-MCP pretreatment suppressed fruit respiration and ethylene production rates, and markedly delayed flesh softening. Normal ripening (ethylene production and flesh softening to eating quality firmness) was observed in 1-MCP treated fruit after 42 d at 20 degrees C, and 112 d at 5 degrees C. Subsequent RNA-Seq analysis revealed that 6,427 genes, including those associated with ethylene biosynthesis (ACS1, ACS1b, ACO1, and ACO2), cell wall degrading enzymes (PG3, fl-GAL, EG, and EXP1), and transcription factors (AGL18 and NAC29) were up -or down-regulated in non-treated fruit both at 20 degrees C and 5 degrees C. The expression patterns of these genes were disrupted by 1-MCP pretreatment, but up-or down-regulation was also observed when ethylene was detected in 1-MCP-treated fruit. Together, these findings demonstrate the potential for practical use of 1-MCP to extend storage life in 'La France' pears given that (i) a single application markedly extended storage life to 56 d at 20 degrees C and 112 d at 5 degrees C, and (ii) treated fruit could regain their softening capacity, thus eliminating previous irreversible ripening blockage concerns.