Metabolomic insights into the browning of the peel of bagging ‘Rui Xue’ apple fruit

Abstract Background Bagging is one of the most important techniques for producting high-quality fruits. In actual cultivating, we found a new kind browning in peel apple fruit that occurs before harvest and worsen during storage period. There are many studies on metabonomic analysis about fruits, but few mechanism harvest. Results this study, five-year-old trees ‘Rui Xue’ (CNA20151469.1) were used as materials. fruits without (BFW) bagging with (BFB) set experimental groups, non-bagging (NBF) control. After partial least squares discriminant (PLS-DA), 50 kinds metabolites predictive VIP > 1 p -value < 0.05. The differential include flavonoids lipids molecules, 11 6 molecules significantly decreased BFW compared NBF. browning, 7 further BFB BFW. Meanwhile, enriched metabolic pathways galactose metabolism, ABC membrane transporter protein, flavonoid biosynthesis linoleic acid metabolism et al. Physiological indicators show that, NBF, content malondialdehyde (MDA), hydrogen peroxide (H 2 O ) , superoxide anion (O ? increased, difference was more significant. antioxidant enzyme activities inhibited, which accelerated destruction cell structure. addition, metabolome physiological data showed decrease positively correlated browning. So, analyzed expression related genes synthesis MdLAR MdANR up-regulated BFB, but, downstream flavonoids-related polymeric MdLAC7 MdLAC14 also expressed. Conclusions Our findings demonstrated microenvironment changed by bagging, structure, increase triterpenoids main reasons peel.