Molecular regulation of carotenoid biosynthesis in citrus juice sacs: New advances

Citrus juice sacs, the major edible part of fruit, are one of the richest sources of carotenoids for human nutrition. In the juice sacs, high amounts of carotenoids are accumulated, and their contents and compositions vary greatly among different citrus varieties. In the past decades, the carotenoid in citrus fruit drew a lot of researcher's attention, and significant progress has been made in the elucidation of carotenoid accumulation in the juice sacs of citrus fruit. In this review, the current information on carotenoid accumulation in the juice sacs of citrus fruit was summarized, and the molecular mechanisms that regulated the carotenoid biosynthesis were reviewed. In addition, to improve the carotenoid accumulation in the juice sacs, the effects of different plant growth regu-lators and environmental conditions on carotenoid content and composition were evaluated. This review con-tributes to a better comprehension of carotenoid accumulation in the juice sacs of citrus fruit, which will provide new strategies to enhance the nutritional and commercial values of citrus fruit.