ABSTRACT
Development of crop plants that absorb and use nitrogen more effi ciently has been a long-term goal of agricultural research. In an attempt to develop nitrogen-effi cient rice, plants were genetically engineered by introducing a barley AlaAT (alanine aminotransferase) cDNA driven by a rice tissuespecifi c promoter, OsAnt1 (Shrawat et al., 2008). This modifi cation increased the biomass and grain yield signifi cantly in comparison with control plants when plants were well supplied with nitrogen. Compared with controls, transgenic rice plants also demonstrated signifi cant changes in key metabolites and total nitrogen content, indicating increased nitrogen uptake efficiency. The development of crop plants that take up and assimilate nitrogen more effi ciently would not only improve the use of nitrogen fertilizers, resulting in lower production costs, but would also have signifi cant environmental benefi ts and improved grain quality. Thus
the plant biotechnology can make important contributions to food security and nutritional improvement. For example, the development of “Golden Rice” by Professor Ingo Potrykus, a milestone in the application of gene technology to deliver both increased nutritional qualities and health improvement to wide sections of the human population. Mineral nutrient and protein defi ciency as well as food security remain the most important challenges for developing countries. Since rice is the staple food for half the world population, providing approximately 20% of the per capita energy and 13% of the protein for human consumption worldwide, in many developing countries the dietary contributions of rice are substantially greater (29.3% dietary protein). The current six most popular ‘mega’ rice varieties (in terms of popularity and acreage), including Chinese hybrid rice, have an incomplete amino acid profi le and contain limited amounts of essential micronutrients. The development of rice lines with improved iron contents using genes that have functions in iron absorption, translocation and accumulation in the plant, as well as improved iron bioavailability in the human intestine is a step in this direction.
