“…Moreover, certain amino acids are also precursors of secondary metabolites, such as acetyl coenzyme A, which are formed by the degradation of leucine, isoleucine, lysine and valine, and are important precursor for the synthesis of terpenoids [14,22,[28][29][30][31]. Additionally, many key physiological processes in plants, such as water regulation, cytoskeleton activity, programmed cell death (PCD) activation or root hair growth, are regulated by complex signal transduction networks mediated by lipids [32][33][34][35][36]. Thus, we hypothesized that the accumulation of a large number of primary metabolites is necessary for the rapid development of the young tissues in 1-year-old P. notoginseng taproots, and that these primary metabolites also provides precursors for secondary metabolites production at the later stages of development.…”