title: Metabolic engineering of β-carotene in orange fruit increases its in vivo antioxidant properties.
abstract: Orange is a major crop and an important source of health-promoting bioactive compounds. Increasing the levels of specific antioxidants in orange fruit through metabolic engineering could strengthen the fruit's health benefits. In this work, we have afforded enhancing the β-carotene content of orange fruit through blocking by RNA interference the expression of an endogenous β-carotene hydroxylase gene (Csβ-CHX) that is involved in the conversion of β-carotene into xanthophylls. Additionally, we have simultaneously overexpressed a key regulator gene of flowering transition, the FLOWERING LOCUS T from sweet orange (CsFT), in the transgenic juvenile plants, which allowed us to obtain fruit in an extremely short period of time. Silencing the Csβ-CHX gene resulted in oranges with a deep yellow ('golden') phenotype and significant increases (up to 36-fold) in β-carotene content in the pulp. The capacity of β-carotene-enriched oranges for protection against oxidative stress in vivo was assessed using Caenorhabditis elegans as experimental animal model. Golden oranges induced a 20% higher antioxidant effect than the isogenic control. This is the first example of the successful metabolic engineering of the β-carotene content (or the content of any other phytonutrient) in oranges and demonstrates the potential of genetic engineering for the nutritional enhancement of fruit tree crops.
authors.affiliation: Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, Spain.
authors.forename: Elsa
authors.initials: E
authors.lastname: Pons
authors.forename: Berta
authors.initials: B
authors.lastname: Alquézar
authors.forename: Ana
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Patricia
authors.initials: P
authors.lastname: Martorell
authors.forename: Salvador
authors.initials: S
authors.lastname: Genovés
authors.forename: Daniel
authors.initials: D
authors.lastname: Ramón
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Rodrigo
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Zacarías
authors.forename: Leandro
authors.initials: L
authors.lastname: Peña
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002957:Citrus / Q000378:metabolism*; D005638:Fruit / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism*; D019207:beta Carotene / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D019207:beta Carotene; D006899:Mixed Function Oxygenases; C079232:beta-carotene hydroxylase
keywords: Caenorhabditis elegans; FLOWERING LOCUS T; carotenoids; citrus; genetic transformation; health