Carotenoids are essential compounds for photoprotection in photosynthetic organisms.
Beta-carotene, the pigment of the carrot root and one of the most abundant carotenoids in nature, is synthesized from lycopene by the enzyme lycopene cyclase. An Arabidopsis cDNA library was screened by DNA hybridization with a PCR probe generated by amplifying Arabidopsis genomic and cDNA with primers based on on the dbEST sequence. A number of positives were excised and partially sequenced from both ends. All clones appeared to be from the same gene. The longest cDNA was fully sequenced by the dideoxy method and used in further cloning experiments.