Integrated Analysis of Morphological Alterations, Antioxidant Capacity, and Metabolomic Profiles in Daylily Flower Buds During Storage

Abstract

Daylily flower buds are edible and medical homologous with health care functions and pharmaceutical values. However, they are about to open and deteriorate after harvest, owing to ripening and senescence. To obtain a theoretical reference for understanding the postharvest senescence mechanisms of daylily flower buds, the dynamic quality characteristics of daylily flower buds were explored by physiology, biochemistry, and widely targeted metabolomics. During the whole storage process, texture, total flavonoid contents, and antioxidant activities indicated by DPPH, ABTS, and FRAP assays appeared in declining trends. Based on widely targeted metabolomics, 518, 443, and 507 differentially accumulated metabolites (DAMs) were screened in the initial storage period (CK0 vs. CK2), mid-storage period (CK2 vs. CK4), and the end of storage (CK4 vs. CK6), respectively. A total of 224 common DAMs in CK0 vs. CK2, CK2 vs. CK4, and CK4 vs. CK6 were closely related to the ripening and senescence of daylily. A special focus was given to the interplay between the marker flavonoids and antioxidant activities. 11 flavonoid compounds showed positive correlation with the results of antioxidant capacity, including pelargonidin 3−O−beta−D−glucoside 5−O−(6−coumaroyl−beta−D−glucoside), typhaneoside, 5‴−O−feruloyl complanatoside B, 7−neohesperidosides, taxifolin, rutin (trihydrate), rutin (hydrate), rutin (hydrate), 3,5,7,3′,4′−pentahydroxyflavylium−3−O−beta−D−xylopyranosyl−(1−2)−beta−D−glucopyranoside, kuromanin (chloride), and neoeriocitrin, which have the potential to be biomarkers for antioxidant capacity and daylily quality. The study innovatively served as a valuable guide for the senescence progress and suggested potential markers for the quality characteristics of daylily flower buds.