title: Bioengineered 'golden' indica rice cultivars with beta-carotene metabolism in the endosperm with hygromycin and mannose selection systems.
abstract: Vitamin-A deficiency (VAD) is a major malnutrition problem in South Asia, where indica rice is the staple food. Indica-type rice varieties feed more than 2 billion people. Hence, we introduced a combination of transgenes using the biolistic system of transformation enabling biosynthesis of provitamin A in the endosperm of several indica rice cultivars adapted to diverse ecosystems of different countries. The rice seed-specific glutelin promoter (Gt-1 P) was used to drive the expression of phytoene synthase (psy), while lycopene beta-cyclase (lcy) and phytoene desaturase (crtI), fused to the transit peptide sequence of the pea-Rubisco small subunit, were driven by the constitutive cauliflower mosaic virus promoter (CaMV35S P). Transgenic plants were recovered through selection with either CaMV35S P driven hph (hygromycin phosphotransferase) gene or cestrum yellow leaf curling virus promoter (CMP) driven pmi (phophomannose isomerase) gene. Molecular and biochemical analyses demonstrated stable integration and expression of the transgenes. The yellow colour of the polished rice grain evidenced the carotenoid accumulation in the endosperm. The colour intensity correlated with the estimated carotenoid content by spectrophotometric and HPLC analysis. Carotenoid level in cooked polished seeds was comparable (with minor loss of xanthophylls) to that in non-cooked seeds of the same transgenic line. The variable segregation pattern in T1 selfing generation indicated single to multiple loci insertion of the transgenes in the genome. This is the first report of using nonantibiotic pmi driven by a novel promoter in generating transgenic indica rice for possible future use in human nutrition.
authors.affiliation: International Rice Research Institute, Plant Breeding, Genetics, and Biochemistry Division, DAPO Box 7777, Metro Manila, Philippines.
authors.forename: Karabi
authors.initials: K
authors.lastname: Datta
authors.forename: Niranjan
authors.initials: N
authors.lastname: Baisakh
authors.forename: Norman
authors.initials: N
authors.lastname: Oliva
authors.forename: Lina
authors.initials: L
authors.lastname: Torrizo
authors.forename: Editha
authors.initials: E
authors.lastname: Abrigo
authors.forename: Jing
authors.initials: J
authors.lastname: Tan
authors.forename: Mayank
authors.initials: M
authors.lastname: Rai
authors.forename: Sayda
authors.initials: S
authors.lastname: Rehana
authors.forename: Salim
authors.initials: S
authors.lastname: Al-Babili
authors.forename: Peter
authors.initials: P
authors.lastname: Beyer
authors.forename: Ingo
authors.initials: I
authors.lastname: Potrykus
authors.forename: Swapan K
authors.initials: SK
authors.lastname: Datta