Combination of Beta-carotene biosynthesis and ferritin genes in indica rice

The coexistence of multiple micronutrients (e.g iron, zinc, vitamin A) deficiencies accounts for about two third of the childhood death in Asia where rice is the staple food. Rice plant produces carotenoids but only in the non-edible green parts and not in the grains. Also, rice grain contains small amount of iron and zinc and is distributed more densely in oil-rich aleuron layer than the endosperm; these nutrients are removed with the aleuron layer during polishing. Biofortification of rice with iron, zinc, and carotenoids (mainly Beta-carotene), therefore, is considered as a potential strategy to combat against widespread iron deficiency anemia (IDA) and Vitamin A deficiency (VAD) for the rice-consuming people. The introduction of Beta-carotene biosynthesis pathway to rice endosperm (TP 309, a japonica rice cultivar) by genetic engineering is considered as a milestone in the vitamin A bio-fortification program. Subsequently, the same Beta-carotene biosynthesis pathway was introduced successfully into a Bangladeshi high yielding rice variety, BRRIdhan 29 (an indica rice variety) at IRRI. But this variety has low iron and zinc content in its grains. Another elite breeding line, IR68144-3B-2-2-3, which has initial higher amount of iron and zinc was transformed with soybean ferritin gene to further enhancement of those elements. With a view to combine both of the genes in one rice cultivar, BRRIdhan 29 carrying Beta-carotene biosynthesis genes (SKBR3) and IR68144-3B-2-2-3 carrying ferritin gene (FR19-9) were crossed reciprocally. On the basis of PCR and southern blot analysis, positive plants for both the genes were identified. Grains from positive plants were yellow in color indicating the Beta-carotene deposition in the grains. The colored seeds from individual plants were analysed for carotenoids profile by HPLC. The total carotenoids were as high as to 4.5 ug/g, 50% of which is Beta-carotene. Histochemical study for the presence of iron in the endosperm cells and estimation of iron content are under process.