title: Carotenoid cleavage dioxygenase4 is a negative regulator of β-carotene content in Arabidopsis seeds.
abstract: Experimental approaches targeting carotenoid biosynthetic enzymes have successfully increased the seed β-carotene content of crops. However, linkage analysis of seed carotenoids in Arabidopsis thaliana recombinant inbred populations showed that only 21% of quantitative trait loci, including those for β-carotene, encode carotenoid biosynthetic enzymes in their intervals. Thus, numerous loci remain uncharacterized and underutilized in biofortification approaches. Linkage mapping and genome-wide association studies of Arabidopsis seed carotenoids identified CAROTENOID cleavage dioxygenase4 (CCD4) as a major negative regulator of seed carotenoid content, especially β-carotene. Loss of CCD4 function did not affect carotenoid homeostasis during seed development but greatly reduced carotenoid degradation during seed desiccation, increasing β-carotene content 8.4-fold relative to the wild type. Allelic complementation of a ccd4 null mutant demonstrated that single-nucleotide polymorphisms and insertions and deletions at the locus affect dry seed carotenoid content, due at least partly to differences in CCD4 expression. CCD4 also plays a major role in carotenoid turnover during dark-induced leaf senescence, with β-carotene accumulation again most strongly affected in the ccd4 mutant. These results demonstrate that CCD4 plays a major role in β-carotene degradation in drying seeds and senescing leaves and suggest that CCD4 orthologs would be promising targets for stabilizing and increasing the level of provitamin A carotenoids in seeds of major food crops.
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Gonzalez-Jorge
authors.forename: Sun-Hwa
authors.initials: SH
authors.lastname: Ha
authors.forename: Maria
authors.initials: M
authors.lastname: Magallanes-Lundback
authors.forename: Laura Ullrich
authors.initials: LU
authors.lastname: Gilliland
authors.forename: Ailing
authors.initials: A
authors.lastname: Zhou
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Lipka
authors.forename: Yen-Nhu
authors.initials: YN
authors.lastname: Nguyen
authors.forename: Ruthie
authors.initials: R
authors.lastname: Angelovici
authors.forename: Haining
authors.initials: H
authors.lastname: Lin
authors.forename: Jason
authors.initials: J
authors.lastname: Cepela
authors.forename: Holly
authors.initials: H
authors.lastname: Little
authors.forename: C Robin
authors.initials: CR
authors.lastname: Buell
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gore
authors.forename: Dean
authors.initials: D
authors.lastname: Dellapenna
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016922:Cellular Senescence; D002874:Chromosome Mapping; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006706:Homeostasis; D016254:Mutagenesis, Insertional; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D012639:Seeds / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D019207:beta Carotene / Q000096:biosynthesis*
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; D019207:beta Carotene; C000592331:CCD4 protein, Arabidopsis; D049308:Dioxygenases; C109043:9-cis-epoxy-carotenoid dioxygenase