Metabolome analysis elucidates the mechanism of radish taproot hollowness during the storage

ABSTRACT: The hollowness phenomenon of radish (Raphanus sativus L.) root is very easy to occur during the storage, which seriously affects its quality. “Weixian radish” was used as the test material, and metabolomics technology and multivariate statistical analysis were employed to explore the underlying mechanism. The results revealed 384 differential metabolites in VL0 vs VL1 (174 up-regulated, 210 down-regulated), 440 differential metabolites in VL0 vs VL4 (279 up-regulated, 161 down-regulated), and 298 differential metabolites in VL1 vs VL4 (226 up-regulated, 72 down-regulated). The KEGG enrichment analysis indicated that a total of four metabolic pathways were significantly enriched in the process of radish hollowness. Notably, only cysteine and methionine metabolism was significantly enriched in the comparisons of VL0 vs VL1 and VL0 vs VL4 positive ions. Therefore, the cysteine and methionine metabolism could be the most critical metabolic pathway involved in the response of radish taproots to the hollowness phenomenon. The study suggested that a decrease in homocysteine content may lead to reducing glutathione levels, impacting the antioxidant capacity of radish taproots. In conclusion, hollowness may indirectly influence the anabolism of glucosinolates in radish taproots by affecting the metabolism of cysteine and methionine, as well as the biosynthetic pathways of phenylalanine, tyrosine, and tryptophan, thereby impacting the antioxidant capacity of radish taproots.