iTRAQ-Based Proteomic Analyses of Regulation of Isothiocyanate and Endogenous Selenium Metabolism in Broccoli Sprouts by Exogenous Sodium Selenite

Broccoli sprouts have high isothiocyanate and selenium accumulation capacity. This study used a combination of methods, including physiological and biochemical, gene transcription and proteomic, to investigate the isothiocyanate and endogenous selenium accumulation mechanisms in broccoli sprouts under exogenous sodium selenite treatment during germination. Compared with the control, the sprouts length of broccoli sprouts under exogenous selenium treatment was significantly lower, and the contents of total phenol and malondialdehyde in 6-day-old broccoli sprouts were substantially higher. The contents of isothiocyanate and sulforaphane in 4-day-old were increased by up-regulating the relative expression of genes of UGT74B1, OX-1, and ST5b. The relative expression of BoSultr1;1, BoSMT, BoHMT1, and BoCOQ5-2 genes regulating selenium metabolism was significantly up-regulated. In addition, 354 proteins in 4-day-old broccoli sprouts showed different relative abundance compared to the control under selenium treatment. These proteins were classified into 14 functional categories. It was discovered that metabolic pathways and biosynthetic pathways of secondary metabolites were significantly enriched. The above results showed that exogenous selenium was beneficial in inducing the accumulation of isothiocyanate and selenium during the growth of broccoli sprouts.

Automated summary

This study investigated the mechanisms of isothiocyanate and selenium accumulation in broccoli sprouts under exogenous sodium selenite treatment. The results showed that the growth of broccoli sprouts was inhibited and the contents of total phenol and malondialdehyde were increased in 6-day-old sprouts under exogenous selenium treatment. The expression of genes regulating isothiocyanate and sulforaphane biosynthesis was up-regulated, while genes regulating selenium metabolism were significantly up-regulated. Furthermore, the proteomic analysis revealed different abundance of proteins related to metabolic pathways and biosynthetic pathways of secondary metabolites in 4-day-old broccoli sprouts under selenium treatment.