title: ZmcrtRB3 encodes a carotenoid hydroxylase that affects the accumulation of α-carotene in maize kernel.
abstract: α-carotene is one of the important components of pro-vitamin A, which is able to be converted into vitamin A in the human body. One maize (Zea mays L.) ortholog of carotenoid hydroxylases in Arabidopsis thaliana, ZmcrtRB3, was cloned and its role in carotenoid hydrolyzations was addressed. ZmcrtRB3 was mapped in a quantitative trait locus (QTL) cluster for carotenoid-related traits on chromosome 2 (bin 2.03) in a recombinant inbred line (RIL) population derived from By804 and B73. Candidate-gene association analysis identified 18 polymorphic sites in ZmcrtRB3 significantly associated with one or more carotenoid-related traits in 126 diverse yellow maize inbred lines. These results indicate that the enzyme ZmcrtRB3 plays a role in hydrolyzing both α- and β-carotenes, while polymorphisms in ZmcrtRB3 contributed more variation in α-carotene than that in β-carotene. Two single nucleotide polymorphisms (SNPs), SNP1343 in 5'untranslated region and SNP2172 in the second intron, consistently had effects on α-carotene content and composition with explained phenotypic variations ranging from 8.7% to 34.8%. There was 1.7- to 3.7-fold change between the inferior and superior haplotype for α-carotene content and composition. Thus, SNP1343 and SNP2172 are potential polymorphic sites to develop functional markers for applying marker-assisted selection in the improvement of pro-vitamin A carotenoids in maize kernels.
authors.affiliation: National Maize Improvement Center, Key Laboratory of Crop Genomics and Genetic Improvement, China Agricultural University, 100193 Beijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yingjia
authors.initials: Y
authors.lastname: Han
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Fu
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Fu
authors.forename: Shutu
authors.initials: S
authors.lastname: Xu
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Li
authors.forename: Jianbing
authors.initials: J
authors.lastname: Yan
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Yang
mesh_terms: D002338:Carotenoids / Q000378:metabolism*; D003001:Cloning, Molecular; D015870:Gene Expression; D014644:Genetic Variation; D015810:Linkage Disequilibrium; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D040641:Quantitative Trait Loci; D012639:Seeds / Q000378:metabolism*; D003313:Zea mays / Q000201:enzymology / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D002338:Carotenoids; C041635:alpha-carotene; D006899:Mixed Function Oxygenases