Lysine (Lys) is the first limiting essential amino acid in rice which is a stable food for half of the world population.Efforts,including genetic engineering approach,thus far have not achieved a desirable level of Lys in rice.In this study,we engineered rice for increased Lys through expressing the bacterial Lys feedback-insensitive aspartate kinase (AK) and dihydrodipicolinate synthase (DHPS) genes to enhance Lys biosynthesis; through RNA interference of rice bifunetional lysine ketoglutaric acid reductase/saccharopine dehydropine dehydrogenase (LKR/SDH) gene to down-regulate Its catabolism; andby combined expression of bacterial AK and DHPS and interference of LKR/SDH genes to achieve both metabolic effects.