5 7Carrot (Daucus carota subsp. carota L.; 2n = 2x = 18) is a globally important root crop whose production has quadrupled between 1976 and 2013 (FAO Statistics; see URLs), outpacing the overall rate of increase in vegetable production and world population growth (FAO Statistics; see URLs) through development of high-value products for fresh consumption, juices, and natural pigments and cultivars adapted to warmer production regions 1 .The first documented colors for domesticated carrot root were yellow and purple in Central Asia approximately 1,100 years ago 2,3 , with orange carrots not reliably reported until the sixteenth century in Europe 4,5 . The popularity of orange carrots is fortuitous for modern consumers because the orange pigmentation results from high quantities of alpha-and beta-carotene, making carrots the richest source of provitamin A in the US diet 6 . Carrot breeding has substantially increased nutritional value, with a 50% average increase in carotene content in the United States as compared to 40 years ago 6 . Lycopene and lutein in red and yellow carrots, respectively, are also nutritionally important carotenoids, making carrot a model system to study storage root development and carotenoid accumulation.Carrot is the most important crop in the Apiaceae family, which includes numerous other vegetables, herbs, spices, and medicinal plants that enhance the epicurean experience 7 , including celery, parsnip, arracacha, parsley, fennel, coriander, and cumin. The Apiaceae family belongs to the euasterid II clade, which includes important crops such as lettuce and sunflower 8 . Genome sequences of euasterid I species have been reported, but only two genomes 9,10 have been published among the other euasterid II species.Here we report a high-quality genome assembly of a doubledhaploid orange carrot, characterization of the mechanism controlling carotenoid accumulation in storage roots, and the resequencing of 35 accessions spanning the genetic diversity of the Daucus genus. Our comprehensive genomic analyses provide insights into the evolution of the asterids and several gene families. These results will facilitate biological discovery and crop improvement in carrot and other crops.A high-quality carrot genome assembly provides new insights into carotenoid accumulation and asterid genome evolution We report a high-quality chromosome-scale assembly and analysis of the carrot (Daucus carota) genome, the first sequenced genome to include a comparative evolutionary analysis among members of the euasterid II clade. We characterized two new polyploidization events, both occurring after the divergence of carrot from members of the Asterales order, clarifying the evolutionary scenario before and after radiation of the two main asterid clades. Large- and small-scale lineage-specific duplications have contributed to the expansion of gene families, including those with roles in flowering time, defense response, flavor, and pigment accumulation. We identified a candidate gene, DCAR_032551, that conditions caro...

The application of next-generation sequencing (NGS) technologies for the development of simple sequence repeat (SSR) or microsatellite loci for genetic research in the botanical sciences is described. Microsatellite markers are one of the most informative and versatile DNA-based markers used in plant genetic research, but their development has traditionally been a difficult and costly process. NGS technologies allow the efficient identification of large numbers of microsatellites at a fraction of the cost and effort of traditional approaches. The major advantage of NGS methods is their ability to produce large amounts of sequence data from which to isolate and develop numerous genome-wide and gene-based microsatellite loci. The two major NGS technologies with emergent application in SSR isolation are 454 and Illumina. A review is provided of several recent studies demonstrating the efficient use of 454 and Illumina technologies for the discovery of microsatellites in plants. Additionally, important aspects during NGS isolation and development of microsatellites are discussed, including the use of computational tools and high-throughput genotyping methods. A data set of microsatellite loci in the plastome and mitochondriome of cranberry (Vaccinium macrocarpon Ait.) is provided to illustrate a successful application of 454 sequencing for SSR discovery. In the future, NGS technologies will massively increase the number of SSRs and other genetic markers available to conduct genetic research in understudied but economically important crops such as cranberry.