Abstract: The present invention relates to a nucleic acid construct having a nucleic acid molecule configured to silence ?-carotene hydroxylase expression, and host cells, expression systems, plants, and plant seeds having the nucleic acid construct. The present invention also relates to a method of enhancing beta-carotene content by growing a transgenic plant from a plant or seed transformed with the construct.

Abstract: The cauliflower (Brassica oleracea L. var. botrytis) Or gene is a semi-dominant, single-locus mutation. It induces the accumulation of high levels of beta-carotene in various tissues that are normally devoid of carotenoids, turning them orange. Using a map-based cloning strategy, we identified a single candidate gene representing Or and successfully verified its identity by phenotypic complementation in the wild type cauliflower. The Or gene encodes a plastid membrane protein containing the DnaJ zinc figure domain. A likely gain-of-function mutation from a 4.3-kb retrotransposon insertion in the Or allele confers the orange phenotype in the mutant. Southern blot analysis revealed that Or is a single-copy sequence in the cauliflower genome. High level of expression of the Or gene and the protein was found in very young leaves, curds, and flowers at comparable abundance between wild type and the Or mutant.

Abstract: The present invention relates to a nucleic acid construct having a nucleic acid molecule configured to silence ?-carotene hydroxylase expression, and host cells, expression systems, plants, and plant seeds having the nucleic acid construct. The present invention also relates to a method of enhancing beta-carotene content by growing a transgenic plant from a plant or seed transformed with the construct.