CarrotDB: a genomic and transcriptomic database for carrot.

Carrot (Daucus carota L.) is an economically important vegetable worldwide and is the largest source of carotenoids and provitamin A in the human diet. Given the importance of this vegetable to humans, research and breeding communities on carrot should obtain useful genomic and transcriptomic information. The first whole-genome sequences of 'DC-27' carrot were de novo assembled and analyzed. Transcriptomic sequences of 14 carrot genotypes were downloaded from the Sequence Read Archive (SRA) database of National Center for Biotechnology Information (NCBI) and mapped to the whole-genome sequence before assembly. Based on these data sets, the first Web-based genomic and transcriptomic database for D. carota (CarrotDB) was developed (database homepage: http://apiaceae.njau.edu.cn/carrotdb). CarrotDB offers the tools of Genome Map and Basic Local Alignment Search Tool. Using these tools, users can search certain target genes and simple sequence repeats along with designed primers of 'DC-27'. Assembled transcriptomic sequences along with fragments per kilobase of transcript sequence per millions base pairs sequenced information (FPKM) information of 14 carrot genotypes are also provided. Users can download de novo assembled whole-genome sequences, putative gene sequences and putative protein sequences of 'DC-27'. Users can also download transcriptome sequence assemblies of 14 carrot genotypes along with their FPKM information. A total of 2826 transcription factor (TF) genes classified into 57 families were identified in the entire genome sequences. These TF genes were embedded in CarrotDB as an interface. The 'GERMPLASM' part of CarrotDB also offers taproot photos of 45 carrot genotypes and a table containing accession numbers, names, countries of origin and colors of cortex, phloem and xylem parts of taproots corresponding to each carrot genotype. CarrotDB will be continuously updated with new information. Database URL: http://apiaceae.njau.edu.cn/carrotdb/