Advances in the endogenous and exogenous regulation of anthocyanins-the key to color change in eudicots

Anthocyanins are important water-soluble pigments that are widely found in plants and determine the color of plant organs, which possess significant health and economic value. The anthocyanin biosynthetic pathway is well established and some key regulators controlling this pathway have been identified in a variety of species. In recent years, microRNAs, transcription factors, and external factors, including light, temperature and hormones have emerged as central regulators of a variety of secondary metabolic responses, including anthocyanin metabolism, as both plant self-regulatory factors and environmental signals that stimulate plant development. Many discoveries have begun to suggest gene/signal-gene modules to reveal the signaling pathways involved in anthocyanin biosynthesis during fruit ripening and the links between specific genes. This paper reviews the internal and external factors and associated network mechanisms that regulate anthocyanin biosynthesis and accumulation in eudicots plants. miRNAs have different effects on the biosynthesis of anthocyanins in different species by binding to their target genes to form regulatory modules. The review also focuses on the conclusion that light signals (light quality, photoperiod, and light intensity) further regulate anthocyanin accumulation by binding to their corresponding photoreceptors (UVR8, CRYs, and PHYs) and affecting the binding and stabilization of the central regulators of the light pathway, such as COP1 and the transcription factor HY5. This article aims to provide a reference for future research on the regulation of anthocyanin by effective pathways, and to contribute to the selection of new varieties and the improvement of cultivation facilities.