Transcriptome and physiological determination reveal the effects of selenite on the growth and selenium metabolism in mung bean sprouts

•Low concentration of selenite is conducive to mungbean germination and growth, and can increase the fresh weight (FW) and dry weight (DW) of sprouts.•Mungbean seeds soaked with 80 mg/kg Na2SeO3 can account for 93.77% of organic selenium after growing for about 5 days.•The main Se amino acid in mungbean sprouts is SeMet, which mainly exists in leaves and stems.•In cotyledons, Se(IV) passes through PHT1.1, NIP2, SULTR3; 3 transport to shoots and roots.•SMT, Met synthase, CBL and other catalytic enzymes play a essential role in the transformation of Se(IV) to Se amino acids during bean sprout germination.