Effect of molybdenum on secondary metabolic process of glycyrrhizic acid in Glycyrrhiza uralensis Fisch.

A pot experiment was conducted to investigate into effects of molybdenum (Mo) on the secondary metabolic process of glycyrrhizic acid (GA). One-year-old seedlings were grown in pots with washed vermiculite and sand. Hoagland nutrition solution was irrigated with four concentrations: 0, 0.52, 5.2 and 10.4 mg L-1. The accumulations of GA and its biosynthetic precursors (beta-amyrin and squalene) and then expression of the key synthase (beta-amyrin synthase, beta-AS) were studied on 35, 70 and 105 d. In the early stage, that was on the 35 and 70 d, the contents of squalene and GA, and the expression of beta-AS gene under 0.52 and 5.2 mg L-1 Mo treatments were significantly higher than that under 0 and 10.4 mg L-1 Mo. There was a contrary result of beta-amyrin. However, the content of squalene under 0 mg L-1 Mo was the highest on 105 d. Thus, it suggested an appropriate concentration of Mo could promote the accumulation of GA, by affecting the biosynthetic process of GA at a certain time. Practically, the time and amount of application of Mo on Glycyrrhiza uralensis should be the noted. (C) 2013 Elsevier Ltd. All rights reserved.