Metabolome and transcriptome profiling reveal the effect of 1-MCP (1-methylcyclopropene) and Ethrel (2-chloroethyl phosphonic acid) treatments on volatile metabolism in postharvest pear fruit

As an effective ethylene action inhibitor, 1-methylcyclopropene (1-MCP) could delay ripening and senescence processes of the climacteric fruits. However, our knowledge on the effects of pre-storage 1-MCP treatment on the expression patterns of aromatic volatiles and their biosynthesis-related genes during pear fruit ripening is still rudimentary. In this study, ‘Housui’ fruit at commercial mature stage were respectively treated with 0.5 mL L⁻¹ 2-chloroethyl phosphonic acid (ethrel) and 1.5 μL L⁻¹ 1-MCP prior to metabolome and transcriptome assays to reveal the regulatory mechanism of 1-MCP on volatile components. 1-MCP treatment significantly suppressed respiration rate and ethylene evolution, and thus the ripening of pear fruit. Moreover, 1-MCP up-regulated the expression levels of most DEGs in association with the reduced abundances of most DEVOCs; on the other hand, a opposite phenomenon was observed for the ethrel-treated fruit. For linolenic acid-derived volatile components, when compared with H₂O (CK) and ethrel treatments, 1-MCP fumigation promoted the expression of PbrLOXs and PbrADHs, leading to the elevated accumulation of 3-hexenal and 3-hexenol. Taken together, our results implicated that 1-MCP and ethrel demonstrated opposite role in aroma compound synthesis during ripening process of ‘Housui’ fruit; in addition, 1-MCP could maintain the quality of postharvest fruit via the enhancement of linolenic acid metabolism. This study provided theoretical basis and technical support for storage and preservation of pears.