Protein elicitor isolated from Escherichia coli induced bioactive compound biosynthesis as well as gene expression in Glycyrrhiza uralensis Fisch adventitious roots

This study explored the ability of three rhizobacterial strains (Bacillus subtilis, Penicillium fellutanum and Escherichia coli) to trigger metabolism. The protein fragment of more than 10 kDa significantly increased the metabolite contents in Glycyrrhiza uralensis adventitious roots. The results showed the highest accumulation of total flavonoids (7.59 mg g(-1)), glycyrrhizic acid (0.29 mg g(-1)), glycyrrhetinic acid (0.27 mg g(-1)) and polysaccharide (93.11 mg g(-1)) by up to 2.27-fold, 2.64-fold, 2.70-fold and 2.32-fold that of control roots, respectively. Besides, the protein fragment of more than 10 kDa significantly activated defense signaling and extremely up-regulated the expression of defense-related genes and functional genes in glycyrrhizic acid and flavonoid biosynthesis. In Glycyrrhiza uralensis adventitious roots, HPLC-ESI-MSn analysis showed that the protein fragment of more than 10 kDa induced the generation of four new compounds over the control group.