Mechanisms of low-intensity hydrostatic pressure pretreatment on nutrition accumulation in fresh kiwifruit: Integrated physiological, widely targeted metabolomics, and transcriptomics analysis.

Abstract

This study investigated the molecular mechanisms of nutrition enhancement in kiwifruits immediately after low-intensity hydrostatic pressure (LHP, 50-200 MPa) and during storage by physiology, transcriptomics, and metabolomics. It indicated that the total phenolic and total sugar content effectively increased by 56% and 27%, respectively, in response to LHP, ultimately improving the antioxidant ability of kiwifruits by 31%. Besides, LHP significantly promoted respiration rate and ROS level, inducing oxidative stress, also stimulated the antioxidant enzyme activities. More importantly, polyphenols were identified as the most abundant metabolites, and LHP evidently improved the relative content of 48 key polyphenols (with 8 polyphenols first identified). Transcriptomics found that 71 key genes regulating polyphenol biosynthesis pathways (including PAL and CHS) were upregulated responding to LHP. To summarize, LHP may improve the nutrition quality of kiwifruits by inducing immediate and late stress to regulate biosynthesis pathways, positioned as an emerging non-thermal pretreatment for producing high-quality fruits.