Targeted metabolomic and transcriptomic reveal the regulatory network of ultrasound on polyphenol biosynthesis in tender coconut flesh during storage.

Coconut flesh, the solid endosperm, of coconut, which is rich in fat, protein and polyphenols. To investigate the impact of ultrasound treatment on the biosynthesis of polyphenols in tender coconut flesh during storage, the targeted metabolomic and transcriptomic analyses were employed. A total of 36 phenolic compounds were identified, of which catechin, epicatechin, gossypol and vanillic acid were the most abundant ones in 'Hainan Tall' coconut flesh. Ultrasound treatment maintained the levels of syringic acid, catechin and epicatechin, while suppressing the expression of most associated genes. Correlation analysis revealed that, downregulation expressions of , , , and decreased kaempferol, isoliquiritigenin and luteoloside content but increased catechin content. Furthermore, downregulation of , and reduced contents of luteolin, whereas downregulation of and elevated the contents of catechin and epicatechin. Unraveling the effect of ultrasound on phenolic biosynthesis in the tender coconut flesh at metabolite and transcript levels provides technical and theoretical support for the high-value development and utilization of Hainan coconut resources.