Molecular networks of secondary metabolism accumulation in plants: Current understanding and future challenges

Plant secondary metabolites are the outcomes of the adaptation of plants to ecological environment changes in the long-term evolution. The accumulation of secondary metabolites not only affects the evolutionary adaptability of plants, but also affects the quality and yield of some medicinal plants and crops. Therefore, it is an indispensable research field to understand further the mechanism of regulating secondary metabolism accumulation in plant science. Recent studies have confirmed that some signaling pathways are involved in regulating the accumulation of plant secondary metabolites, containing the ubiquitin-proteasome pathway, mitogen-activated protein kinase (MAPK) signaling, epigenomic regulatory pathway, plant hormone, and some transcriptional factors. This review summarizes the latest molecular mechanisms and regulatory networks regulating secondary metabolism accumulation, and discusses the difficulties in future research.