Abstract: Astaxanthin, a red-colored ketocarotenoid, has stronger antioxidant activity than other carotenoids or vitamin E. It has been reported in anti-aging, improving immunity, preventing and treating several diseases and widely used in pharmaceuticals, nutraceuticals, and the aquaculture industry. However, β-carotene ketolase genes exist only in some species of microalgae, bacteria and yeast and not in most higher animals and plants. Humans consume astaxanthin mainly from some seafood, such as salmon, shellfish, and trout. Rice, as the most important food crop in the world, is the main grain of nearly half of the world and two thirds of China’s population. However, rice lacks carotenoid precursors, and the engineered biosynthesis of astaxanthin in rice has not been successful. Recently, Chinese scientists successfully engineered sophisticated β-carotene, keratin and astaxanthin biosynthesis in rice endosperm by the self-made multi-gene stacking expression system, which achieved precise synthesis from precursors and intermediate to final products regulated by a complex metabolic network.

Key words: astaxanthin, biofortification, multiple gene transformation, rice