Comparative Proteomics Identified Proteins in Mung Bean Sprouts Under Different Concentrations of Urea

Mung bean (Vigna radiate) sprouts are a popular choice among sprouted vegetables in Asia. Currently, the impact of nitrogen sources on the growth of mung bean sprouts remains poorly understood, and the underlying biological mechanisms responsible for the observed nonlinear growth patterns at different nitrogen levels have yet to be elucidated. In this research, in addition to conventional growth monitoring and quality evaluation, a comparative proteomics method was applied to investigate the molecular mechanisms of mung bean in response to 0, 0.025, 0.05, 0.075, and 0.1% urea concentrations. Our results indicated that mung bean sprout height and yield increased with rising urea concentrations but were suppressed beyond the L3 level (0.075% urea). Nitrate nitrogen and free amino acid content rose steadily with urea levels, whereas protein content, nitrate reductase activity, and nitrite levels followed a peak-then-decline trend, peaking at intermediate concentrations. Differential expression protein analysis was conducted on mung bean sprouts treated with different concentrations of urea, and more differentially expressed proteins participated in the L3 urea concentration. Analysis of common differential proteins among comparison groups showed that the mung bean sprouts enhanced their adaptability to urea stress environments by upregulating chlorophyll a-b binding protein and cationic amino acid transporter and downregulating the levels of glycosyltransferase, L-ascorbic acid, and cytochrome P450. The proteomic analysis uncovered the regulatory mechanisms governing these metabolic pathways, identifying 47 differentially expressed proteins (DEPs) involved in the biosynthesis of proteins, free amino acids, and nitrogen-related metabolites.