Integrated omics reveal the mechanisms underlying softening and aroma changes in pear during postharvest storage and the role of melatonin.

backgroundPyrus ussuriensis Maxim. are rich in nutrients, with a pleasant aroma and postharvest softening properties. Postharvest softening influences shelf life of fruit and fruit quality. Melatonin is a natural and safe preservative, which can effectively maintain fruit quality after harvesting, and delay softening of fruit. The aim of study was to elucidate mechanism of pear fruit softening and fruit aroma during postharvest storage and effect of melatonin.

resultsEthylene production rate, respiration rate, weight loss of fruit, soluble solid content, titratable acidity were assessed, and transmission electron microscopy, metabolite profiling, and whole-transcriptome RNA-sequencing were performed. Four important pathways that pentose and glucuronate interconversion, galactose metabolism, sphingolipid metabolism and the starch and sucrose metabolism pathway were involved in pear fruit softening. Ethylene production pathway-related genes, such as ACS and ACO were involved in pear fruit softening and expression of that under exogenous melatonin treatment were slightly inhibited. Fruit aroma changed after storage mainly through lipoxygenase pathway under ddH

conclusionsThis study indicated that degradation of cell wall caused pear fruit softening, lipoxygenase pathway mainly affected change of fruit aroma during postharvest storage and exogenous melatonin treatment could improve fruit firmness after storage and alter pear's aroma. The mechanism underlying these effects was elucidated, providing theoretical basis for study of pear fruit softening and preservation technology.