Molecular Mechanisms Determining the Differential Accumulation of Carotenoids in Plant Species and Varieties

Abstract Carotenoids are one of the most abundant natural pigments on earth. They accumulate in plastids and play many important roles in biological processes in plants. The structure and quantity of carotenoids vary extensively in different plant species and varieties and over the past three decades the molecular mechanisms underlying these differences have been elucidated. Multiple mechanisms have been discovered, including evolution of novel carotenogenic enzymes and novel catalytic functions, alteration in carotenogenic enzyme activity caused by gene body sequence mutations, changes in gene expression resulting from promoter mutations, difference in expression of noncarotenogenic genes involved in regulation of carotenoid sequestration, plastid sink capacity or transcriptional and epigenetic regulation, as well as effects of related metabolic events. These mechanisms are summarized here, with the aim of providing guidance for future studies on this topic and for genetic manipulation of carotenoid accumulation in plants.