Engineering provitamin A synthesis pathway with β-carotene metabolism in rice endosperm of a restorer line BR827R

Abstract

Vitamin A deficiency (VAD) is a serious public health problem in South Asia particularly in Bangladesh. Indica rice as a major staple in the country completely lacks vitamin A or compounds with provitamin A activity after milling. A combination of transgenes has been introduced enabling biosynthesis of provitamin A in the endosperm of a restorer line using biolistic system of transformation. The rice seed-specific glutelin promoter (Gt-1 P) was used to drive the expression of phytone synthase (psy), while lycopene b-cyclase (lcy) and phytoenedesaturase (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 CaMV35sP driven hph (hygromycinphosphotransferase) gene. Molecular analysis demonstrated stable integration and expression of the transgenes. The variable segregation pattern in T1 generation indicated single to multiple insertions of the transgenes in the genome. This is the first report of the development of a transgenic restorer line with carotenogenic pathway into the endosperm for use of hybrid rice improvement.