Tice is a major staple food for half of the world population.However, rice is deficient in essential amino acid lysine and other nutrients such as vitamin A.We have been using various approaches to enhance the lysine content in rice, including enhancement through increase of a) protein-bound lysine, by expressing heterologous and homologous lysine-rich proteins, and b) free lysine, by metabolic engineering of the lysine synthesis and catabolic pathway.Systematic studies including promoter analysis, expression profiling, enzyme engineering, subcellular localization, allergenicity testing, and animal feeding have been carrying out for optimum results.