Submitted to: Handbook of Plant Breeding
Publication Type: Book / chapter
Publication Acceptance Date: 11/11/2007
Publication Date: 3/17/2008
Citation: Simon, P.W., Freeman, R.E., Vieira, J.V., Boiteux, L.S., Briard, M., Nothnagel, T., Michalik, B., Kwon, Y. 2008. Carrot. In: Prohens, J., Nuez, F. editors. Handbook of Plant Breeding. Volume 2. New York, NY: Springer. p. 327-357. Interpretive Summary:
Technical Abstract: Carrot is among the top-ten most economically important vegetable crops in the world, in terms of both area of production and market value. The development of cultivars adapted for cultivation in both summer and winter seasons on all continents has allowed a year-round availability of carrot products with relatively stable prices to consumers. Some production areas harvest crops year-round. Carrot improvement today includes several academic and government research programs around the world that work in concert with local, regional, and global industries. Both grower and consumer needs are addressed by public and private carrot breeders that incorporate modern technologies into the classical breeding process. The genetic improvement of carrot has been an ongoing effort throughout its cultivation and domestication. Before the 20th century, carrot production was small-scale in family or community gardens. The first carrots were separated into two groups based upon root color: purple and yellow. With the development of orange carrots in the west, shape and size also became distinguishing characteristics of carrot types, starting with the description of “Long Orange” and shorter “Horn” types in the 16th century. In the 20th century there was a significant emphasis on first discovering a CMS system for carrot and then applying that system to develop carrot as a hybrid crop. The uniformity typical of hybrids that is so desirable for growers is usually very evident when two fairly inbred and unrelated inbreds are intercrossed, but less hybrid vigor and uniformity may be observed upon intercrossing less inbred individuals. Genetics of carrot typically follows diploid inheritance patterns, but relatively little effort has been devoted to carrot genetics. The inheritance of male sterility was described, and the male fertile, petaloid, and brown anther mitochondrial genomes have also been characterized. QTL have been mapped for carrot total carotenoids and five component carotenoids; phytoene, alpha-carotene, beta-carotene, zeta-carotene, and lycopene . Marker-assisted selection has been reported for two genes: Mj – 1 and Rs As the genetics of important complex traits become described, markers to more efficiently select them will warrant development. An international collaborative effort to establish robust genomic platforms (e.g. mapping populations, expression sequence tags, subtractive and large-insert libraries, allele mining, large-scale sequencing banks and expression arrays) for carrot and other Apiaceae would greatly facilitate the identification of molecular markers and discovery of genes associated with traits of breeding interest.