Genetics and Genomics of Carrot Sugars and Polyacetylenes

Carrot root carbohydrates, composed mainly of reducing and non-reducing free sugars, influence flavor, total dissolved solids and dry mater content, all quality traits for fresh-market and processing carrots. In the last decades, important advances have been made in biochemistry, physiology and genetics of carrot sugar metabolism. Several enzymes involved in sucrose metabolism and their corresponding genes have been isolated and functionally characterized, increasing our understanding of their individual roles and of their interactions in complex regulatory systems that influence major plant physiological processes, including partitioning of photo-assimilates, plant growth and storage of different sugar types in the carrot taproot. Polyacetylenes represent a large group of non-volatile lipid compounds produced primarily by members of the Apiaceae family. The major carrot polyacetylenes have been extensively studied with regard to their analytical identification and elucidation of their chemical structures as well as their biological activities, which have revealed numerous health-promoting properties for these compounds. Very recently, with the publication of the carrot genome sequence and related genomic and transcriptomic sequence resources, key genes and enzymes involved in the biosynthesis of carrot polyacetylenes were discovered. In this chapter, advances in genetics and genomics of carrot sugars and polyacetylenes were reviewed and discussed.