Multiplex analyses of the changes of aromatic compounds during the development of peach fruit using GC-MS and iTRAQ proteomic techniques

This study aimed to combine GC-MS and iTRAQ techniques to investigate the changes in aromatic compounds and protein profiles of peach fruit peel (Prunus persica cv. Hujiingmilu) at its different developmental stages. The fruits were collected 50, 90, 95, 100, and 105 days after flowering. GC-MS during development and ripening revealed more than 200 volatile compounds, and 18 of them were aroma-related. Based on the varying amount and pattern, gamma-decalactone, delta-decalactone, hexyl acetate, and 1-hexanol were involved in peach aroma. Proteomic analysis with the iTRAQ technique identified 1848 unique proteins, out of which 842 were related to biological processes and 100 related with aromatic compounds and energy transfer during fruit development and ripening. The up-regulated linoleate 9(S)-lipoxygenase plays an important role in the increase of hexanal and benzaldehyde content during ripening. The activity of phosphoglycerate mutase, glyceraldehyde 3-phosphate dehydrogenase, and inorganic pyrophosphatase regulated the terpenoids production for linalool through the 3-phosphoglyceric acid/pyruvic acid pathway but not the mevalonic acid pathway. Caffeoyl-CoA-O-methyltransferase had linear interactions with 4-coumarate-CoA ligase and 3-hydroxyisobutyryl-CoA hydrolase, and it might be the critical pathway of aromatic compounds during the development of peach fruit. Overall, the fatty acid metabolism was the primary pathway for aromatic compound formation in peach fruit and the AOC, AOS, LOX, and OPR were the key functional proteins for the formation of lactones and esters representing the characteristic aroma of honey peach. This study combined the techniques of GC-MS and proteomics to delineate the relationship between the change of aromatic compounds and proteins and their possible biological processes with aroma formation in peach fruit during development and ripening.