Abstract: Glucosinolates are amino acid-erived secondary metabolites. Aliphatic glucosinolates are derived from methionine and have diverse biological activity dependent on chemical modification of the side chain. According to the glucosinolates profile in different tissues of Arabidopsis (Arabidopsis thaliana) combined with bioinformatics analysis, we predicted that there is possible reduction reaction from methylsulfinylalkyl glucosinolates to methythioalkyl glucosinolates in aliphatic glucosinolates side chain modification and peptide methionine sulfoxide reductase 2(PMSR2) might be the candidate gene. To verify this assumption, transgenic plants overexpressing PMSR2 were established. Glucosinolates profile was determined and compared in PMSR2 overexpression line, wild type and pmsr2 mutant. Overexpression of PMSR2 did not alter glucosinolates profile but pmsr2 mutant showed higher MS GSL/MT GSL. The results indicated that PMSR2 is involved in side-hain modification of aliphatic glucosinolates and catalyze the conversion from methylsulfinylalkyl to methythioalkyl glucosinolates by S-educing. The identification of PMSR2 as a reductase in glucosinolates side-hain modification is helpful to better understand the biosynthesis and function of aliphatic glucosinolates.

Key words: Aliphatic glucosinolates, side-hain modification, S-eduction, Peptide methionine sulfoxide reductase, PMSR2