Interaction of Gamma-Aminobutyric Acid and Ca on Phenolic Compounds Bioaccumulation in Soybean Sprouts under NaCl Stress.

NaCl stress can enhance the accumulation of phenolic compounds in soybean during germination. In the present study, effects of gamma-aminobutyric acid (GABA) and Ca on the biosynthesis of phenolic compounds in soybean sprouts germinated with NaCl stress were investigated. Results showed that addition of Ca increased the content of total phenolics, phenolic acids, and isoflavonoids in soybean sprouts by ca. 15%, 7%, and 48%, respectively, through enhancing the activities of three key enzymes involved in the biosynthesis. On the other hand, addition of LaCl, a calcium channel blocker, inhibited the synthesis of phenolic compounds, indicating that Ca plays an important role in the synthesis of these compounds in soybean sprouts. Addition of GABA can increase the content of Ca in soybean sprouts by ca. 20% and alleviate the inhibition of LaCl on phenolics biosynthesis in soybean sprouts. Similarly, addition of Ca can reverse the inhibition of 3-mercaptopropionate, an inhibitor of endogenous GABA synthesis, on the biosynthesis of phenolic compounds in soybean sprouts under NaCl stress. To conclude, both GABA and Ca can enhance the biosynthesis of phenolic compounds in soybean sprouts and there was an interaction between their effects on the promotion of phenolic compounds biosynthesis.