Putative Light-independent Pathways Regulating Anthocyanin Biosynthesis in Horticultural Plants

Anthocyanins constitute an important class of plant flavonoids responsible for color formation and antioxidant processes in flowers, fruits, and other plant organs. Anthocyanin biosynthesis during the maturation of horticultural plant products is influenced by environmental factors and plant hormones. In most horticultural plants, anthocyanin biosynthesis is light-dependent. When subjected to artificial darkness using bags, the fruits and flowers of light-dependent horticultural plants cease anthocyanin production, thereby turning white or yellow. In contrast, fruits and flowers of light-independent horticultural plants do not entirely depend on light for coloring, and anthocyanins accumulation occurs even in complete darkness, suggesting distinct pathways of anthocyanin biosynthesis. This review explores the molecular mechanisms of light-independent anthocyanin biosynthesis in horticultural plants, such as fruits, vegetables, and ornamental plants. In addition, horticultural plants have been categorized into five broad classes based on their underlying mechanisms of action of light-independent anthocyanin.